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NAME:
AD2XY
PURPOSE:
Compute X and Y from native coordinates and a FITS astrometry structure
EXPLANATION:
If a WCS projection (Calabretta & Greisen 2002, A&A, 395, 1077) is
present, then the procedure WCSXY2SPH is used to compute native
coordinates. If distortion is present then this is corrected.
In all cases, the inverse of the CD matrix is applied and offset
from the reference pixel to obtain X and Y.
AD2XY is generally meant to be used internal to other procedures. For
interactive purposes, use ADXY.
CALLING SEQUENCE:
AD2XY, a ,d, astr, x, y
INPUTS:
A - R.A. or longitude in DEGREES, scalar or vector
D - Dec. or longitude in DEGREES, scalar or vector
ASTR - astrometry structure, output from EXTAST procedure containing:
.CD - 2 x 2 array containing the astrometry parameters CD1_1 CD1_2
in DEGREES/PIXEL CD2_1 CD2_2
.CDELT - 2 element vector giving increment at reference point in
DEGREES/PIXEL
.CRPIX - 2 element vector giving X and Y coordinates of reference pixel
(def = NAXIS/2) in FITS convention (first pixel is 1,1)
.CRVAL - 2 element vector giving coordinates of the reference pixel
in DEGREES
.CTYPE - 2 element vector giving projection types
.LONGPOLE - scalar longitude of north pole (default = 180)
.PV2 - Vector of additional parameter (e.g. PV2_1, PV2_2) needed in
some projections
.DISTORT - Optional substructure specifying distortion parameters
OUTPUTS:
X - row position in pixels, scalar or vector
Y - column position in pixels, scalar or vector
X,Y will be in the standard IDL convention (first pixel is 0), and
*not* the FITS convention (first pixel is 1)
NOTES:
AD2XY tests for presence of WCS coordinates by the presence of a dash
in the 5th character position in the value of CTYPE (e.g 'DEC--SIN').
PROCEDURES USED:
TAG_EXIST(), WCSSPH2XY
REVISION HISTORY:
Converted to IDL by B. Boothman, SASC Tech, 4/21/86
Use astrometry structure, W. Landsman Jan. 1994
Do computation correctly in degrees W. Landsman Dec. 1994
Only pass 2 CRVAL values to WCSSPH2XY W. Landsman June 1995
Don't subscript CTYPE W. Landsman August 1995
Understand reversed X,Y (X-Dec, Y-RA) axes, W. Landsman October 1998
Consistent conversion between CROTA and CD matrix W. Landsman October 2000
No special case for tangent projection W. Landsman June 2003
Work for non-WCS coordinate transformations W. Landsman Oct 2004
Use CRVAL reference point for non-WCS transformation W.L. March 2007
Use post V6.0 notation W.L. July 2009
(See astrolib/pro/ad2xy.pro)
NAME:
ADSTRING
PURPOSE:
Return RA and Dec as character string(s) in sexagesimal format.
EXPLANATION:
RA and Dec may be entered as either a 2 element vector or as
two separate vectors (or scalars). One can also specify the precision
of the declination in digits after the decimal point.
CALLING SEQUENCE
result = ADSTRING( ra_dec, precision, /TRUNCATE )
or
result = ADSTRING( ra,dec,[ precision, /TRUNCATE ] )
or
result = ADSTRING( dec, [ PRECISION= ]
INPUTS:
RA_DEC - 2 element vector giving the Right Ascension and declination
in decimal degrees.
or
RA - Right ascension in decimal degrees, numeric scalar or vector
DEC - Declination in decimal degrees, numeric scalar or vector
If only parameter is supplied then it must be either a scalar (which
is converted to sexagesimal) or a two element [RA, Dec] vector.
OPTIONAL INPUT:
PRECISION - Integer scalar (0-4) giving the number of digits after the
decimal of DEClination. The RA is automatically 1 digit more.
This parameter may either be the third parameter after RA,DEC
or the second parameter after [RA,DEC]. If only DEC is supplied
then precision must be supplied as a keyword parameter. If no
PRECISION parameter or keyword is passed, a precision of 1 for
both RA and DEC is returned to maintain compatibility with past
ADSTRING versions. Values of precision larger than 4 will
be truncated to 4. If PRECISION is 3 or 4, then RA and Dec
should be input as double precision.
OPTIONAL INPUT KEYWORD:
/TRUNCATE - if set, then the last displayed digit in the output is
truncated in precision rather than rounded. This option is
useful if ADSTRING() is used to form an official IAU name
(see http://vizier.u-strasbg.fr/Dic/iau-spec.htx) with
coordinate specification. The IAU name will typically be
be created by applying STRCOMPRESS/REMOVE) after the ADSTRING()
call, e.g.
strcompress( adstring(ra,dec,0,/truncate), /remove) ;IAU format
PRECISION = Alternate method of supplying the precision parameter,
OUTPUT:
RESULT - Character string(s) containing HR,MIN,SEC,DEC,MIN,SEC formatted
as ( 2I3,F5.(p+1),2I3,F4.p ) where p is the PRECISION
parameter. If only a single scalar is supplied it is
converted to a sexagesimal string (2I3,F5.1).
EXAMPLE:
(1) Display CRVAL coordinates in a FITS header, H
IDL> crval = sxpar(h,'CRVAL*') ;Extract 2 element CRVAL vector (degs)
IDL> print, adstring(crval) ;Print CRVAL vector sexagesimal format
(2) print,adstring(30.42,-1.23,1) ==> ' 02 01 40.80 -01 13 48.0'
print,adstring(30.42,+0.23) ==> ' 02 01 40.8 +00 13 48.0'
print,adstring(+0.23) ==> '+00 13 48.0'
(3) The first two calls in (2) can be combined in a single call using
vector input
print,adstring([30.42,30.42],[-1.23,0.23], 1)
PROCEDURES CALLED:
RADEC, SIXTY()
REVISION HISTORY:
Written W. Landsman June 1988
Addition of variable precision and DEC seconds precision fix.
ver. Aug. 1990 [E. Deutsch]
Output formatting spiffed up October 1991 [W. Landsman]
Remove ZPARCHECK call, accept 1 element vector April 1992 [W. Landsman]
Call ROUND() instead of NINT() February 1996 [W. Landsman]
Check roundoff past 60s October 1997 [W. Landsman]
Work for Precision =4 November 1997 [W. Landsman]
Major rewrite to allow vector inputs W. Landsman February 2000
Fix possible error in seconds display when Precision=0
P. Broos/W. Landsman April 2002
Added /TRUNCATE keyword, put leading zeros in seconds display
P. Broos/W. Landsman September 2002
Fix declination zero values under vector processing W.Landsman Feb 2004
Fix possible problem in leading zero display W. Landsman June 2004
Assume since V5.4, omit fstring() call W. Landsman April 2006
Fix significant bug when round a declination with -199.99 W. L. Sep 2012
(See astrolib/pro/adstring.pro)
NAME:
ADXY
PURPOSE:
Use a FITS header to convert astronomical to pixel coordinates
EXPLANATION:
Use an image header to compute X and Y positions, given the
RA and Dec (or longitude, latitude) in decimal degrees.
CALLING SEQUENCE:
ADXY, HDR ;Prompt for Ra and DEC
ADXY, hdr, a, d, x, y, [ /PRINT, ALT= ]
INPUTS:
HDR - FITS Image header containing astrometry parameters
OPTIONAL INPUTS:
A - Right ascension in decimal DEGREES, scalar or vector
D - Declination in decimal DEGREES, scalar or vector
If A and D are not supplied, user will be prompted to supply
them in either decimal degrees or HR,MIN,SEC,DEG,MN,SC format.
OPTIONAL OUTPUT:
X - row position in pixels, same number of elements as A and D
Y - column position in pixels
X and Y will be in standard IDL convention (first pixel is 0) and not
the FITS convention (first pixel is 1). As in FITS an integral
value corresponds to the center of a pixel.
OPTIONAL KEYWORD INPUT:
/PRINT - If this keyword is set and non-zero, then results are displayed
at the terminal.
ALT - single character 'A' through 'Z' or ' ' specifying an alternate
astrometry system present in the FITS header. The default is
to use the primary astrometry or ALT = ' '. If /ALT is set,
then this is equivalent to ALT = 'A'. See Section 3.3 of
Greisen & Calabretta (2002, A&A, 395, 1061) for information about
alternate astrometry keywords.
OPERATIONAL NOTES:
If less than 5 parameters are supplied, or if the /PRINT keyword is
set, then the X and Y positions are displayed at the terminal.
If the procedure is to be used repeatedly with the same header,
then it would be faster to use AD2XY.
PROCEDURES CALLED:
AD2XY, ADSTRING(), EXTAST, GETOPT(), TEN()
REVISION HISTORY:
W. Landsman HSTX January, 1988
Use astrometry structure W. Landsman January, 1994
Changed default ADSTRING format W. Landsman September, 1995
Check if latitude/longitude reversed in CTYPE keyword W. L. Feb. 2004
Added ALT keyword W. Landsman September 2004
Work for non-spherical coordinate transformation W. Landsman May 2005
More informative error message if astrometry missing W.L. Feb 2008
Cosmetic updates W.L. July 2011
(See astrolib/pro/adxy.pro)
NAME:
AIRTOVAC
PURPOSE:
Convert air wavelengths to vacuum wavelengths
EXPLANATION:
Wavelengths are corrected for the index of refraction of air under
standard conditions. Wavelength values below 2000 A will not be
altered. Uses relation of Ciddor (1996).
CALLING SEQUENCE:
AIRTOVAC, WAVE_AIR, [ WAVE_VAC]
INPUT/OUTPUT:
WAVE_AIR - Wavelength in Angstroms, scalar or vector
If this is the only parameter supplied, it will be updated on
output to contain double precision vacuum wavelength(s).
OPTIONAL OUTPUT:
WAVE_VAC - Vacuum wavelength in Angstroms, same number of elements as
WAVE_AIR, double precision
EXAMPLE:
If the air wavelength is W = 6056.125 (a Krypton line), then
AIRTOVAC, W yields an vacuum wavelength of W = 6057.8019
METHOD:
Formula from Ciddor 1996, Applied Optics 62, 958
NOTES:
Take care within 1 A of 2000 A. Wavelengths below 2000 A *in air* are
not altered.
REVISION HISTORY
Written W. Landsman November 1991
Use Ciddor (1996) formula for better accuracy in the infrared
Added optional output vector, W Landsman Mar 2011
Iterate for better precision W.L./D. Schlegel Mar 2011
(See astrolib/pro/airtovac.pro)
NAME:
AITOFF
PURPOSE:
Convert longitude, latitude to X,Y using an AITOFF projection.
EXPLANATION:
This procedure can be used to create an all-sky map in Galactic
coordinates with an equal-area Aitoff projection. Output map
coordinates are zero longitude centered.
CALLING SEQUENCE:
AITOFF, L, B, X, Y
INPUTS:
L - longitude - scalar or vector, in degrees
B - latitude - same number of elements as L, in degrees
OUTPUTS:
X - X coordinate, same number of elements as L. X is normalized to
be between -180 and 180
Y - Y coordinate, same number of elements as L. Y is normalized to
be between -90 and 90.
NOTES:
See AIPS memo No. 46, page 4, for details of the algorithm. This
version of AITOFF assumes the projection is centered at b=0 degrees.
REVISION HISTORY:
Written W.B. Landsman STX December 1989
Modified for Unix:
J. Bloch LANL SST-9 5/16/91 1.1
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/aitoff.pro)
NAME:
AITOFF_GRID
PURPOSE:
Produce an overlay of latitude and longitude lines over a plot or image
EXPLANATION:
The grid is plotted on the current graphics device. AITOFF_GRID
assumes that the ouput plot coordinates span the x-range of
-180 to 180 and the y-range goes from -90 to 90.
CALLING SEQUENCE:
AITOFF_GRID [,DLONG,DLAT, LABEL=, /NEW, CHARTHICK=, CHARSIZE=,
FONT=, _EXTRA=]
OPTIONAL INPUTS:
DLONG = Optional input longitude line spacing in degrees. If left
out, defaults to 30.
DLAT = Optional input latitude line spacing in degrees. If left
out, defaults to 30.
OPTIONAL INPUT KEYWORDS:
LABEL = Optional keyword specifying that the latitude and
longitude lines on the prime meridian and the
equator should be labeled in degrees. If LABELS is
given a value of 2, i.e. LABELS=2, then the longitude
labels will be in hours instead of degrees.
CHARSIZE = If /LABEL is set, then CHARSIZE specifies the size
of the label characters (passed to XYOUTS)
CHARTHICK = If /LABEL is set, then CHARTHICK specifies the
thickness of the label characters (passed to XYOUTS)
FONT = scalar font graphics keyword (-1,0 or 1) for text
/NEW = If this keyword is set, then AITOFF_GRID will create
a new plot grid, rather than overlay an existing plot.
Any valid keyword to OPLOT such as COLOR, LINESTYLE, THICK can be
passed to AITOFF_GRID (though the _EXTRA facility) to to specify the
color, style, or thickness of the grid lines.
OUTPUTS:
Draws grid lines on current graphics device.
EXAMPLE:
Create a labeled Aitoff grid of the Galaxy, and overlay stars at
specified Galactic longitudes, glong and latitudes, glat
IDL> aitoff_grid,/label,/new ;Create labeled grid
IDL> aitoff, glong, glat, x,y ;Convert to X,Y coordinates
IDL> plots,x,y,psym=2 ;Overlay "star" positions
PROCEDURES USED:
AITOFF
NOTES:
If labeling in hours (LABEL=2) then the longitude spacing should be
a multiple of 15 degrees
AUTHOR AND MODIFICATIONS:
J. Bloch 1.2 6/2/91
Converted to IDL V5.0 W. Landsman September 1997
Create default plotting coords, if needed W. Landsman August 2000
Added _EXTRA, CHARTHICK, CHARSIZE keywords W. Landsman March 2001
Several tweaks, plot only hours not minutes W. Landsman January 2002
Allow FONT keyword to be passed to XYOUTS. T. Robishaw Apr. 2006
(See astrolib/pro/aitoff_grid.pro)
NAME:
ALTAZ2HADEC
PURPOSE:
Convert Horizon (Alt-Az) coordinates to Hour Angle and Declination.
EXPLANATION::
Can deal with the NCP singularity. Intended mainly to be used by
program hor2eq.pro
CALLING SEQUENCE:
ALTAZ2HADEC, alt, az, lat, ha, dec
INPUTS
alt - the local apparent altitude, in DEGREES, scalar or vector
az - the local apparent azimuth, in DEGREES, scalar or vector,
measured EAST of NORTH!!! If you have measured azimuth west-of-south
(like the book MEEUS does), convert it to east of north via:
az = (az + 180) mod 360
lat - the local geodetic latitude, in DEGREES, scalar or vector.
OUTPUTS
ha - the local apparent hour angle, in DEGREES. The hour angle is the
time that right ascension of 0 hours crosses the local meridian.
It is unambiguously defined.
dec - the local apparent declination, in DEGREES.
EXAMPLE:
Arcturus is observed at an apparent altitude of 59d,05m,10s and an
azimuth (measured east of north) of 133d,18m,29s while at the
latitude of +43.07833 degrees.
What are the local hour angle and declination of this object?
IDL> altaz2hadec, ten(59,05,10), ten(133,18,29), 43.07833, ha, dec
===> Hour angle ha = 336.683 degrees
Declination, dec = 19.1824 degrees
The widely available XEPHEM code gets:
Hour Angle = 336.683
Declination = 19.1824
REVISION HISTORY:
Written Chris O'Dell Univ. of Wisconsin-Madison May 2002
(See astrolib/pro/altaz2hadec.pro)
NAME:
AL_LEGEND
PURPOSE:
Create an annotation legend for a plot.
EXPLANATION:
This procedure was originally named LEGEND, but a distinct LEGEND()
function was introduced into IDL V8.0. Therefore, the
original LEGEND procedure in the Astronomy Library is renamed to
AL_LEGEND.
This procedure makes a legend for a plot. The legend can contain
a mixture of symbols, linestyles, Hershey characters (vectorfont),
and filled polygons (usersym). A test procedure, al_legendtest.pro,
shows legend's capabilities. Placement of the legend is controlled
with keywords like /right, /top, and /center or by using a position
keyword for exact placement (position=[x,y]) or via mouse (/position).
CALLING SEQUENCE:
AL_LEGEND [,items][,keyword options]
EXAMPLES:
The call:
al_legend,['Plus sign','Asterisk','Period'],psym=[1,2,3]
produces:
-----------------
| |
| + Plus sign |
| * Asterisk |
| . Period |
| |
-----------------
Each symbol is drawn with a cgPlots command, so they look OK.
Other examples are given in optional output keywords.
lines = indgen(6) ; for line styles
items = 'linestyle '+strtrim(lines,2) ; annotations
al_legend,items,linestyle=lines ; vertical legend---upper left
items = ['Plus sign','Asterisk','Period']
sym = [1,2,3]
al_legend,items,psym=sym ; ditto except using symbols
al_legend,items,psym=sym,/horizontal ; horizontal format
al_legend,items,psym=sym,box=0 ; sans border
al_legend,items,psym=sym,delimiter='=' ; embed '=' betw psym & text
al_legend,items,psym=sym,margin=2 ; 2-character margin
al_legend,items,psym=sym,position=[x,y] ; upper left in data coords
al_legend,items,psym=sym,pos=[x,y],/norm ; upper left in normal coords
al_legend,items,psym=sym,pos=[x,y],/device ; upper left in device coords
al_legend,items,psym=sym,/position ; interactive position
al_legend,items,psym=sym,/right ; at upper right
al_legend,items,psym=sym,/bottom ; at lower left
al_legenditems,psym=sym,/center ; approximately near center
al_legend,items,psym=sym,number=2 ; plot two symbols, not one
Plot 3 filled colored squares
al_legend,items,/fill,psym=[8,8,8],colors=['red','green','blue']
Another example of the use of AL_LEGEND can be found at
http://www.idlcoyote.com/cg_tips/al_legend.php
INPUTS:
items = text for the items in the legend, a string array.
For example, items = ['diamond','asterisk','square'].
You can omit items if you don't want any text labels.
OPTIONAL INPUT KEYWORDS:
linestyle = array of linestyle numbers If linestyle[i] < 0, then omit
ith symbol or line to allow a multi-line entry. If
linestyle = -99 then text will be left-justified.
psym = array of plot symbol numbers or names. If psym[i] is negative,
then a line connects pts for ith item. If psym[i] = 8, then the
procedure USERSYM is called with vertices defined in the
keyword usersym. If psym[i] = 88, then use the previously
defined user symbol. If 11 <= psym[i] <= 46 then David
Fanning's function CGSYMCAT() will be used for additional
symbols. Note that
PSYM=10 (histogram plot mode) is not allowed since it
cannot be used with the cgPlots command.
vectorfont = vector-drawn characters for the sym/line column, e.g.,
['!9B!3','!9C!3','!9D!3'] produces an open square, a checkmark,
and a partial derivative, which might have accompanying items
['BOX','CHECK','PARTIAL DERIVATIVE'].
There is no check that !p.font is set properly, e.g., -1 for
X and 0 for PostScript. This can produce an error, e.g., use
!20 with PostScript and !p.font=0, but allows use of Hershey
*AND* PostScript fonts together.
N. B.: Choose any of linestyle, psym, and/or vectorfont. If none is
present, only the text is output. If more than one
is present, all need the same number of elements, and normal
plot behaviour occurs.
By default, if psym is positive, you get one point so there is
no connecting line. If vectorfont[i] = '',
then cgPlots is called to make a symbol or a line, but if
vectorfont[i] is a non-null string, then cgText is called.
/help = flag to print header
/horizontal = flag to make the legend horizontal
/vertical = flag to make the legend vertical (D=vertical)
background_color - color name or number to fill the legend box.
Automatically sets /clear. (D = -1)
box = flag to include/omit box around the legend (D=include)
outline_color = color of box outline (D = !P.color)
bthick = thickness of the legend box (D = !P.thick)
charsize = just like !p.charsize for plot labels
charthick = just like !p.charthick for plot labels
clear = flag to clear the box area before drawing the legend
colors = array of colors names or numbers for plot symbols/lines
See cgCOLOR for list of color names. Default is 'Opposite'
If you are using index colors (0-255), then supply color as a byte,
integer or string, but not as a long, which will be interpreted as
a decomposed color. See http://www.idlcoyote.com/cg_tips/legcolor.php
delimiter = embedded character(s) between symbol and text (D=none)
font = scalar font graphics keyword (-1,0 or 1) for text
linsize = Scale factor for line length (0-1), default = 1
Set to 0 to give a dot, 0.5 give half default line length
margin = margin around text measured in characters and lines
number = number of plot symbols to plot or length of line (D=1)
spacing = line spacing (D=bit more than character height)
position = data coordinates of the /top (D) /left (D) of the legend
pspacing = psym spacing (D=3 characters) (when number of symbols is
greater than 1)
textcolors = array of color names or numbers for text. See cgCOLOR
for a list of color names. Default is 'Opposite' of background
thick = array of line thickness numbers (D = !P.thick), if used, then
linestyle must also be specified
normal = use normal coordinates for position, not data
device = use device coordinates for position, not data
/window - if set then send legend to a resizeable graphics window
usersym = 2-D array of vertices, cf. usersym in IDL manual.
(/USERSYM =square, default is to use existing USERSYM definition)
/fill = flag to fill the usersym
/left_legend = flag to place legend snug against left side of plot
window (D)
/right_legend = flag to place legend snug against right side of plot
window. If /right,pos=[x,y], then x is position of RHS and
text runs right-to-left.
/top_legend = flag to place legend snug against top of plot window (D)
/bottom = flag to place legend snug against bottom of plot window
/top,pos=[x,y] and /bottom,pos=[x,y] produce same positions.
If LINESTYLE, PSYM, VECTORFONT, SYMSIZE, THICK, COLORS, or
TEXTCOLORS are supplied as scalars, then the scalar value is set for
every line or symbol in the legend.
Outputs:
legend to current plot device
OPTIONAL OUTPUT KEYWORDS:
corners = 4-element array, like !p.position, of the normalized
coords for the box (even if box=0): [llx,lly,urx,ury].
Useful for multi-column or multi-line legends, for example,
to make a 2-column legend, you might do the following:
c1_items = ['diamond','asterisk','square']
c1_psym = [4,2,6]
c2_items = ['solid','dashed','dotted']
c2_line = [0,2,1]
al_legend,c1_items,psym=c1_psym,corners=c1,box=0
al_legend,c2_items,line=c2_line,corners=c2,box=0,pos=[c1[2],c1[3]]
c = [c1[0]c2[2],c1[3]>c2[3]]
cgplots,[c[0],c[0],c[2],c[2],c[0]],[c[1],c[3],c[3],c[1],c[1]],/norm
Useful also to place the legend. Here's an automatic way to place
the legend in the lower right corner. The difficulty is that the
legend's width is unknown until it is plotted. In this example,
the legend is plotted twice: the first time in the upper left, the
second time in the lower right.
al_legend,['1','22','333','4444'],linestyle=indgen(4),corners=corners
; BOGUS LEGEND---FIRST TIME TO REPORT CORNERS
xydims = [corners[2]-corners[0],corners[3]-corners[1]]
; SAVE WIDTH AND HEIGHT
chdim=[!d.x_ch_size/float(!d.x_size),!d.y_ch_size/float(!d.y_size)]
; DIMENSIONS OF ONE CHARACTER IN NORMALIZED COORDS
pos = [!x.window[1]-chdim[0]-xydims[0] $
,!y.window[0]+chdim[1]+xydims[1]]
; CALCULATE POSITION FOR LOWER RIGHT
cgplot,findgen(10) ; SIMPLE PLOT; YOU DO WHATEVER YOU WANT HERE.
al_legend,['1','22','333','4444'],linestyle=indgen(4),pos=pos
; REDO THE LEGEND IN LOWER RIGHT CORNER
You can modify the pos calculation to place the legend where you
want. For example to place it in the upper right:
pos = [!x.window[1]-chdim[0]-xydims[0],!y.window[1]-xydims[1]]
Common blocks:
none
Procedure:
If keyword help is set, call doc_library to print header.
See notes in the code. Much of the code deals with placement of the
legend. The main problem with placement is not being
able to sense the length of a string before it is output. Some crude
approximations are used for centering.
Restrictions:
Here are some things that aren't implemented.
- An orientation keyword would allow lines at angles in the legend.
- An array of usersyms would be nice---simple change.
- An order option to interchange symbols and text might be nice.
- Somebody might like double boxes, e.g., with box = 2.
- Another feature might be a continuous bar with ticks and text.
- There are no guards to avoid writing outside the plot area.
- There is no provision for multi-line text, e.g., '1st line!c2nd line'
Sensing !c would be easy, but !c isn't implemented for PostScript.
A better way might be to simply output the 2nd line as another item
but without any accompanying symbol or linestyle. A flag to omit
the symbol and linestyle is linestyle[i] = -1.
- There is no ability to make a title line containing any of titles
for the legend, for the symbols, or for the text.
Side Effects:
Modification history:
write, 24-25 Aug 92, F K Knight ([email protected])
allow omission of items or omission of both psym and linestyle, add
corners keyword to facilitate multi-column legends, improve place-
ment of symbols and text, add guards for unequal size, 26 Aug 92, FKK
add linestyle(i)=-1 to suppress a single symbol/line, 27 Aug 92, FKK
add keyword vectorfont to allow characters in the sym/line column,
28 Aug 92, FKK
add /top, /bottom, /left, /right keywords for automatic placement at
the four corners of the plot window. The /right keyword forces
right-to-left printing of menu. 18 Jun 93, FKK
change default position to data coords and add normal, data, and
device keywords, 17 Jan 94, FKK
add /center keyword for positioning, but it is not precise because
text string lengths cannot be known in advance, 17 Jan 94, FKK
add interactive positioning with /position keyword, 17 Jan 94, FKK
allow a legend with just text, no plotting symbols. This helps in
simply describing a plot or writing assumptions done, 4 Feb 94, FKK
added thick, symsize, and clear keyword Feb 96, W. Landsman HSTX
David Seed, HR Wallingford, [email protected]
allow scalar specification of keywords, Mar 96, W. Landsman HSTX
added charthick keyword, June 96, W. Landsman HSTX
Made keyword names left,right,top,bottom,center longer,
Aug 16, 2000, Kim Tolbert
Added ability to have regular text lines in addition to plot legend
lines in legend. If linestyle is -99 that item is left-justified.
Previously, only option for no sym/line was linestyle=-1, but then text
was lined up after sym/line column. 10 Oct 2000, Kim Tolbert
Make default value of thick = !P.thick W. Landsman Jan. 2001
Don't overwrite existing USERSYM definition W. Landsman Mar. 2002
Added outline_color BT 24 MAY 2004
Pass font keyword to cgText commands. M. Fitzgerald, Sep. 2005
Default spacing, pspacing should be relative to charsize. M. Perrin, July 2007
Don't modify position keyword A. Kimball/ W. Landsman Jul 2007
Small update to Jul 2007 for /NORMAL coords. W. Landsman Aug 2007
Use SYMCAT() plotting symbols for 11<=PSYM<=46 W. Landsman Nov 2009
Make a sharper box edge T. Robishaw/W.Landsman July 2010
Added BTHICK keyword W. Landsman October 2010
Added BACKGROUND_COLOR keyword W. Landsman February 2011
Incorporate Coyote graphics W. Landsman February 2011
Added LINSIZE keyword W.L./V.Gonzalez May 2011
Fixed a small problem with Convert_Coord when the Window keyword is set.
David Fanning, May 2011.
Fixed problem when /clear and /Window are set J. Bailin/WL May 2011
CGQUERY was called instead of CGCONTROL W.L. June 2011
Fixed typo preventing BTHICK keyword from working W.L. Dec 2011
Remove call to SYMCAT() W.L. Dec 2011
Changed the way the WINDOW keyword adds commands to cgWindow, and
now default to BACKGROUND for background color. 1 Feb 2012 David Fanning
Allow 1 element SYMSIZE for vector input, WL Apr 2012.
Allow to specify symbols by cgSYMCAT() name WL Aug 2012
Fixed bug when linsize, /right called simultaneously, Dec 2012, K.Stewart
(See astrolib/pro/al_legend.pro)
NAME:
AL_LEGENDTEST
PURPOSE:
Demo program to show capabilities of the al_legend procedure.
CALLING SEQUENCE:
al_legendtest
INPUTS:
none
OPTIONAL INPUTS:
none
KEYWORDS:
none
OUTPUTS:
legends of note
COMMON BLOCKS:
none
SIDE EFFECTS:
Sets !20 font to symbol if PostScript and !p.font=0.
RESTRICTIONS:
With the vectorfont test, you'll get different results for PostScript
depending on the value of !p.font.
MODIFICATION HISTORY:
write, 27 Aug 92, F.K.Knight ([email protected])
add test of /left,/right,/top,/bottom keywords, 21 June 93, FKK
update based on recent changes to legend, 7 Feb 94, FKK
Fix ambiguous CHAR keyword W. Landsman Sep 2007
Use Coyote graphics routines W. Landsman Jan 2011
(See astrolib/pro/al_legendtest.pro)
NAME:
APER
PURPOSE:
Compute concentric aperture photometry (adapted from DAOPHOT)
EXPLANATION:
APER can compute photometry in several user-specified aperture radii.
A separate sky value is computed for each source using specified inner
and outer sky radii.
CALLING SEQUENCE:
APER, image, xc, yc, [ mags, errap, sky, skyerr, phpadu, apr, skyrad,
badpix, /NAN, /EXACT, /FLUX, PRINT = , /SILENT,
/MEANBACK, MINSKY=, SETSKYVAL = ]
INPUTS:
IMAGE - input image array
XC - vector of x coordinates.
YC - vector of y coordinates
OPTIONAL INPUTS:
PHPADU - Photons per Analog Digital Units, numeric scalar. Converts
the data numbers in IMAGE to photon units. (APER assumes
Poisson statistics.)
APR - Vector of up to 12 REAL photometry aperture radii.
SKYRAD - Two element vector giving the inner and outer radii
to be used for the sky annulus. Ignored if the SETSKYVAL
keyword is set.
BADPIX - Two element vector giving the minimum and maximum value
of a good pixel. If badpix is not supplied or if BADPIX[0] is
equal to BADPIX[1] then it is assumed that there are no bad
pixels. Note that fluxes will not be computed for any star
with a bad pixel within the aperture area, but that bad pixels
will be simply ignored for the sky computation. The BADPIX
parameter is ignored if the /NAN keyword is set.
OPTIONAL KEYWORD INPUTS:
CLIPSIG - if /MEANBACK is set, then this is the number of sigma at which
to clip the background. Default=3
CONVERGE_NUM: if /MEANBACK is set then if the proportion of
rejected pixels is less than this fraction, the iterations stop.
Default=0.02, i.e., iteration stops if fewer than 2% of pixels
excluded.
/EXACT - By default, APER counts subpixels, but uses a polygon
approximation for the intersection of a circular aperture with
a square pixel (and normalizes the total area of the sum of the
pixels to exactly match the circular area). If the /EXACT
keyword, then the intersection of the circular aperture with a
square pixel is computed exactly. The /EXACT keyword is much
slower and is only needed when small (~2 pixels) apertures are
used with very undersampled data.
/FLUX - By default, APER uses a magnitude system where a magnitude of
25 corresponds to 1 flux unit. If set, then APER will keep
results in flux units instead of magnitudes.
MAXITER if /MEANBACK is set then this is the ceiling on number of
clipping iterations of the background. Default=5
/MEANBACK - if set, then the background is computed using the 3 sigma
clipped mean (using meanclip.pro) rather than using the mode
computed with mmm.pro. This keyword is useful for the Poisson
count regime or where contamination is known to be minimal.
MINSKY - Integer giving mininum number of sky values to be used with MMM
APER will not compute a flux if fewer valid sky elements are
within the sky annulus. Default = 20.
/NAN - If set then APER will check for NAN values in the image. /NAN
takes precedence over the BADPIX parameter. Note that fluxes
will not be computed for any star with a NAN pixel within the
aperture area, but that NAN pixels will be simply ignored for
the sky computation.
PRINT - if set and non-zero then APER will also write its results to
a file aper.prt. One can specify the output file name by
setting PRINT = 'filename'.
READNOISE - Scalar giving the read noise (or minimum noise for any
pixel. This value is passed to the procedure mmm.pro when
computing the sky, and is only need for images where
the noise is low, and pixel values are quantized.
/SILENT - If supplied and non-zero then no output is displayed to the
terminal.
SETSKYVAL - Use this keyword to force the sky to a specified value
rather than have APER compute a sky value. SETSKYVAL
can either be a scalar specifying the sky value to use for
all sources, or a 3 element vector specifying the sky value,
the sigma of the sky value, and the number of elements used
to compute a sky value. The 3 element form of SETSKYVAL
is needed for accurate error budgeting.
OUTPUTS:
MAGS - NAPER by NSTAR array giving the magnitude for each star in
each aperture. (NAPER is the number of apertures, and NSTAR
is the number of stars). If the /FLUX keyword is not set, then
a flux of 1 digital unit is assigned a zero point magnitude of
25.
ERRAP - NAPER by NSTAR array giving error for each star. If a
magnitude could not be determined then ERRAP = 9.99 (if in
magnitudes) or ERRAP = !VALUES.F_NAN (if /FLUX is set).
SKY - NSTAR element vector giving sky value for each star in
flux units
SKYERR - NSTAR element vector giving error in sky values
EXAMPLE:
Determine the flux and error for photometry radii of 3 and 5 pixels
surrounding the position 234.2,344.3 on an image array, im. Compute
the partial pixel area exactly. Assume that the flux units are in
Poisson counts, so that PHPADU = 1, and the sky value is already known
to be 1.3, and that the range [-32767,80000] for bad low and bad high
pixels
IDL> aper, im, 234.2, 344.3, flux, eflux, sky,skyerr, 1, [3,5], -1, $
[-32767,80000],/exact, /flux, setsky = 1.3
PROCEDURES USED:
GETOPT, MMM, PIXWT(), STRN(), STRNUMBER()
NOTES:
Reasons that a valid magnitude cannot be computed include the following:
(1) Star position is too close (within 0.5 pixels) to edge of the frame
(2) Less than 20 valid pixels available for computing sky
(3) Modal value of sky could not be computed by the procedure MMM
(4) *Any* pixel within the aperture radius is a "bad" pixel
(5) The total computed flux is negative. In this case the negative
flux and error are returned.
For the case where the source is fainter than the background, APER will
return negative fluxes if /FLUX is set, but will otherwise give
invalid data (since negative fluxes can't be converted to magnitudes)
APER was modified in June 2000 in two ways: (1) the /EXACT keyword was
added (2) the approximation of the intersection of a circular aperture
with square pixels was improved (i.e. when /EXACT is not used)
REVISON HISTORY:
Adapted to IDL from DAOPHOT June, 1989 B. Pfarr, STX
FLUX keyword added J. E. Hollis, February, 1996
SETSKYVAL keyword, increase maxsky W. Landsman, May 1997
Work for more than 32767 stars W. Landsman, August 1997
Don't abort for insufficient sky pixels W. Landsman May 2000
Added /EXACT keyword W. Landsman June 2000
Allow SETSKYVAL = 0 W. Landsman December 2000
Set BADPIX[0] = BADPIX[1] to ignore bad pixels W. L. January 2001
Fix chk_badpixel problem introduced Jan 01 C. Ishida/W.L. February 2001
Set bad fluxes and error to NAN if /FLUX is set W. Landsman Oct. 2001
Remove restrictions on maximum sky radius W. Landsman July 2003
Added /NAN keyword W. Landsman November 2004
Set badflux=0 if neither /NAN nor badpix is set M. Perrin December 2004
Added READNOISE keyword W. Landsman January 2005
Added MEANBACK keyword W. Landsman October 2005
Correct typo when /EXACT and multiple apertures used. W.L. Dec 2005
Remove VMS-specific code W.L. Sep 2006
Add additional keywords if /MEANBACK is set W.L Nov 2006
Allow negative fluxes if /FLUX is set W.L. Mar 2008
Previous update would crash if first star was out of range W.L. Mar 2008
Fix floating equality test for bad magnitudes W.L./J.van Eyken Jul 2009
Added MINSKY keyword W.L. Dec 2011
(See astrolib/pro/aper.pro)
NAME:
ARCBAR
PURPOSE:
Draw an arc bar on an image showing the astronomical plate scale
CALLING SEQUENCE:
ARCBAR, hdr, arclen,[ COLOR= , /DATA, LABEL= , /NORMAL, POSITION =,
/SECONDS, SIZE=, THICK=, FONT= ]
INPUTS:
hdr - image FITS header with astrometry, string array
arclen - numeric scalar giving length of bar in arcminutes (default)
or arcseconds (if /SECONDS is set)
OPTIONAL KEYWORD INPUTS:
COLOR - name or integer scalar specifying the color to draw the arcbar
See cgColor for a list of available color names
/DATA - if set and non-zero, then the POSITION keyword is given in data
units
LABEL - string giving user defined label for bar. Default label is size
of bar in arcminutes
/NORMAL - if this keyword is set and non-zero, then POSITION is given in
normalized units
POSITION - 2 element vector giving the (X,Y) position in device units
(or normalized units if /NORMAL is set, or data units if /DATA
is set) at which to place the scale bar. If not supplied,
then the user will be prompted to place the cursor at the
desired position
/SECONDS - if set, then arlen is specified in arcseconds rather than
arcminutes
SIZE - scalar specifying character size of label, default = 1.0
THICK - Character thickness of the label, default = !P.THICK
FONT - scalar font graphics keyword (-1,0 or 1) for text
EXAMPLE:
Place a 3' arc minute scale bar, at position 300,200 of the current
image window, (which is associated with a FITS header, HDR)
IDL> arcbar, HDR, 3, pos = [300,200]
RESTRICTIONS:
When using using a device with scalable pixels (e.g. postscript)
the data coordinate system must be established before calling ARCBAR.
If data coordinates are not set, then ARCBAR assumes that the displayed
image size is given by the NAXIS1 keyword in the FITS header.
PROCEDURE CALLS:
AD2XY, EXTAST, GSSSADXY, SXPAR(), cgPlot, cgText
REVISON HISTORY:
written by L. Taylor (STX) from ARCBOX (Boothman)
modified for Version 2 IDL, B. Pfarr, STX, 4/91
New ASTROMETRY structures W.Landsman, HSTX, Jan 94
Recognize a GSSS header W. Landsman June 94
Added /NORMAL keyword W. Landsman Feb. 96
Use NAXIS1 for postscript if data coords not set, W. Landsman Aug 96
Fixed typo for postscript W. Landsman Oct. 96
Account for zeropoint offset in postscript W. Landsman Apr 97
Added /DATA, /SECONDS keywords W. Landsman July 1998
Use device-independent label offset W. Landsman August 2001
Allow font keyword to be passed. T. Robishaw Apr. 2006
Remove obsolete TVCURSOR command W. Landsman Jul 2007
Use Coyote Graphics W. Landsman February 2011
(See astrolib/pro/arcbar.pro)
NAME:
ARROWS
PURPOSE:
To display "weathervane" directional arrows on an astronomical image
EXPLANATION:
Overlays a graphic showing orientation of North and East.
CALLING SEQUENCE:
ARROWS,h, [ xcen, ycen, ARROWLEN= , CHARSIZE= COLOR= , /DATA
FONT=, /NORMAL, /NOTVERTEX, THICK= ]
INPUTS:
h - FITS header array, must include astrometry
OPTIONAL INPUTS:
xcen,ycen - numeric scalars, specifying the center position of
arrows. Position in device units unless the /NORMALIZED
keyword is specified. If not supplied, then ARROWS
will prompt for xcen and ycen
OPTIONAL KEYWORD INPUTS:
arrowlen - length of arrows in terms of normal Y size of vector-drawn
character, default = 3.5, floating point scalar
charsize - character size, default = 2.0, floating point scalar
color - color name or number for the arrows and NE letters. See
cgCOLOR() for a list of color names.
Data - if this keyword is set and nonzero, the input center (xcen,
ycen) is understood to be in data coordinates
font - IDL vector font number (1-20) to use to display NE letters.
For example, set font=13 to use complex italic font.
NotVertex - Normally (historically) the specified xcen,ycen indicated
the position of the vertex of the figure. If this
keyword is set, the xcen,ycen coordinates refer to a sort
of 'center of mass' of the figure. This allows the
figure to always appear with the area irregardless of
the rotation angle.
Normal - if this keyword is set and nonzero, the input center
(xcen,ycen) is taken to be in normalized coordinates. The
default is device coordinates.
thick - line thickness, default = 2.0, floating point scalar
OUTPUTS:
none
EXAMPLE:
Draw a weathervane at (400,100) on the currently active window,
showing the orientation of the image associated with a FITS header, hdr
IDL> arrows, hdr, 400, 100
METHOD:
Uses EXTAST to EXTract ASTrometry from the FITS header. The
directions of North and East are computed and the procedure
ONE_ARROW called to create the "weathervane".
PROCEDURES USED:
GETROT - Computes rotation from the FITS header
ONE_ARROW - Draw a labeled arrow
ZPARCHECK
REVISON HISTORY:
written by B. Boothman 2/5/86
Recoded with new procedures ONE_ARROW, ONE_RAY. R.S.Hill,HSTX,5/20/92
Added separate determination for N and E arrow to properly display
arrows irregardless of handedness or other peculiarities and added
/NotVertex keyword to improve positioning of figure. E.Deutsch 1/10/93
Added /DATA and /NORMAL keywords W. Landsman July 1993
Recognize GSSS header W. Landsman June 1993
Added /FONT keyword W. Landsman April 1995
Modified to work correctly for COLOR=0 J.Wm.Parker, HITC 1995 May 25
Work correctly for negative CDELT values W. Landsman Feb. 1996
Use GETROT to compute rotation W. Landsman June 2003
Restored /NotVertex keyword which was not working after June 2003 change
W. Landsman January 2004
(See astrolib/pro/arrows.pro)
NAME:
ASINH
PURPOSE:
Return the inverse hyperbolic sine of the argument
EXPLANATION:
The inverse hyperbolic sine is used for the calculation of asinh
magnitudes, see Lupton et al. (1999, AJ, 118, 1406)
CALLING SEQUENCE
result = asinh( x)
INPUTS:
X - hyperbolic sine, numeric scalar or vector or multidimensional array
(not complex)
OUTPUT:
result - inverse hyperbolic sine, same number of elements as X
double precision if X is double, otherwise floating pt.
METHOD:
Expression given in Numerical Recipes, Press et al. (1992), eq. 5.6.7
Note that asinh(-x) = -asinh(x) and that asinh(0) = 0. and that
if y = asinh(x) then x = sinh(y).
REVISION HISTORY:
Written W. Landsman February, 2001
Work for multi-dimensional arrays W. Landsman August 2002
Simplify coding, and work for scalars again W. Landsman October 2003
(See astrolib/pro/asinh.pro)
NAME: ASTDISP PURPOSE: Print astronomical and pixel coordinates in a standard format EXPLANATION: This procedure (ASTrometry DISPlay) prints the astronomical and pixel coordinates in a standard format. X,Y must be supplied. RA,DEC may also be supplied, and a data number (DN) may also be supplied. With use of the Coords= keyword, a string containing the formatted data can be returned in addition or instead (with /silent) of printing. CALLING SEQUENCE: ASTDISP, x, y, [Ra, Dec, DN, COORD = , /SILENT ] INPUT: X - The X pixel coordinate(s), scalar or vector Y - The Y pixel coordinate(s), scalar or vector OPTIONAL INPUTS: RA - Right Ascension in *degrees*, scalar or vector DEC - DEClination in *degrees*, scalar or vector (if RA is supplied, DEC must also be supplied) DN - Data Number or Flux values Each of the inputs X,Y, RA, DEC, DN should have the same number of elements OPTIONAL INPUT KEYWORDS: SILENT Prevents printing. Only useful when used with Coords= OUTPUT: Printed positions in both degrees and sexagesimal format All passed variables remain unchanged OPTIONAL KEYWORD OUTPUT: COORDS Returns the formatted coordinates in a string PROCEDURES CALLED: ADSTRING - used to format the RA and Dec HISTORY: 10-AUG-90 Version 1 written by Eric W. Deutsch 20-AUG-91 Converted to standard header. Vectorized Code. E. Deutsch 20-NOV-92 Added Coords= and /silent. E.Deutsch Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/astdisp.pro)
NAME:
ASTRO
PURPOSE:
Interactive utility for precession and coordinate conversion.
CALLING SEQUENCE:
ASTRO, [ selection, EQUINOX =, /FK4]
OPTIONAL INPUT:
SELECTION - Scalar Integer (0-6) giving the the particular astronomical
utility to be used. (0) Precession, (1) RA, Dec (2000) to Galactic
coordinates, (2) Galactic to RA,Dec (2000) (3) RA,Dec (2000) to
Ecliptic, (4) Ecliptic to RA, Dec, (5) Ecliptic to Galactic, (6) Galactic
to Ecliptic. Program will prompt for SELECTION if this
parameter is omitted.
OPTIONAL KEYWORD INPUT:
EQUINOX - numeric scalar specifying the equinox to use when converting
between celestial and other coordinates. If not supplied,
then the RA and Dec will be assumed to be in EQUINOX J2000.
This keyword is ignored by the precession utility. For
example, to convert from RA and DEC (J1975) to Galactic
coordinates:
IDL> astro, 1, E=1975
/FK4 - If this keyword is set and nonzero, then calculations are done
in the FK4 system. For example, to convert from RA and Dec
(B1975) to Galactic coordinates
IDL> astro,1, E=1975,/FK4
METHOD:
ASTRO uses PRECESS to compute precession, and EULER to compute
coordinate conversions. The procedure GET_COORDS is used to
read the coordinates, and ADSTRING to format the RA,Dec output.
NOTES:
(1) ASTRO temporarily sets !QUIET to suppress compilation messages and
keep a pretty screen display.
(2) ASTRO was changed in December 1998 to use J2000 as the default
equinox, **and may be incompatible with earlier calls.***
(3) A nice online page for coordinate conversions is available at
http://heasarc.gsfc.nasa.gov/cgi-bin/Tools/convcoord/convcoord.pl
PROCEDURES USED:
Procedures: GET_COORDS, EULER Function: ADSTRING
REVISION HISTORY
Written, W. Landsman November 1987
Code cleaned up W. Landsman October 1991
Added Equinox keyword, call to GET_COORDS, W. Landsman April, 1992
Allow floating point equinox input J. Parker/W. Landsman July 1996
Make FK5 the default, add FK4 keyword
(See astrolib/pro/astro.pro)
NAME:
ASTROLIB
PURPOSE:
Add the non-standard system variables used by the IDL Astronomy Library
EXPLANATION:
Also defines the environment variable ASTRO_DATA pointing to the
directory containing data files associated with the IDL Astronomy
library (system dependent -- user must edit the third line in the
program below).
CALLING SEQUENCE:
ASTROLIB
INPUTS:
None.
OUTPUTS:
None.
METHOD:
The non-standard system variables !PRIV, !TEXTUNIT, and
!TEXTOUT are added using DEFSYSV.
REVISION HISTORY:
Written, Wayne Landsman, July 1986.
Use DEFSYSV instead of ADDSYSVAR December 1990
Test for system variable existence before definition July 2001
Assume since V55, remove VMS support W. Landsman Sep 2006
Remove !Debug, comment out ASTRO_DATA definition WL Jan 2009
(See astrolib/pro/astrolib.pro)
NAME:
AUTOHIST
PURPOSE:
Draw a histogram using automatic bin-sizing.
EXPLANATION
AUTOHIST chooses a number of bins (initially, SQRT(2*N). If this leads
to a histogram in which > 1/5 of the central 50% of the bins are empty,
it decreases the number of bins and tries again. The minimum # bins is
5. The max=199. Called by HISTOGAUSS and HALFAGAUSS.
CALLING SEQUENCE:
AUTOHIST, Sample, XLines, Ylines, XCenters, YCenters, [/NOPLOT, ]
...Plotting Keywords
INPUT:
Sample = the vector to be histogrammed
OUTPUT:
XLINES = vector of x coordinates of the points that trace the rectangular
histogram bins
YLINES = vector of y coordinates. To draw the histogram plot YLINES vs
XLINES
XCENTERS = the x values of the bin centers
YCENTERS = the corresponding y values
OPTIONAL INPUT KEYWORDS:
/NOPLOT If set, nothing is drawn
Any plotting keywords (e.g. XTITLE) may be supplied to AUTOHIST through
the _EXTRA facility.
REVISION HISTORY:
Written, H. Freudenreich, STX, 1/91
1998 March 17 - Changed shading of histogram. RSH, RSTX
V5.0 update, _EXTRA keywords W. Landsman April 2002
Added NOCLIP keyword for POLYFILL call C. Paxson/W. Landsman July 2003
Use Coyote graphics W. Landsman Feb 2011
(See astrolib/pro/autohist.pro)
NAME:
AVG
PURPOSE:
Return the average value of an array, or 1 dimension of an array
EXPLANATION:
Calculate the average value of an array, or calculate the average
value over one dimension of an array as a function of all the other
dimensions.
In 2009, a DIMENSION keyword was added to the IDL MEAN() function,
giving it the same capability as AVG(). Thus, the use of AVG() is now
**deprecated** in favor of the MEAN() function.
CALLING SEQUENCE:
RESULT = AVG( ARRAY, [ DIMENSION, /NAN, /DOUBLE ] )
INPUTS:
ARRAY = Input array. May be any type except string.
OPTIONAL INPUT PARAMETERS:
DIMENSION = Optional dimension to do average over, integer scalar
OPTIONAL KEYWORD INPUT:
/NAN - Set this keyword to cause the routine to check for occurrences of
the IEEE floating-point value NaN in the input data. Elements with
the value NaN are treated as missing data.
/DOUBLE - By default, if the input Array is double-precision, complex,
or double complex, the result is of the same type; 64 bit
integers are also returned as double. Otherwise the result
the result is floating-point. Use of the /DOUBLE keyword
forces a double precision output. Note that internal
computations are always done in double precision.
OUTPUTS:
The average value of the array when called with one parameter.
If DIMENSION is passed, then the result is an array with all the
dimensions of the input array except for the dimension specified,
each element of which is the average of the corresponding vector
in the input array.
For example, if A is an array with dimensions of (3,4,5), then the
command B = AVG(A,1) is equivalent to
B = FLTARR(3,5)
FOR J = 0,4 DO BEGIN
FOR I = 0,2 DO BEGIN
B[I,J] = TOTAL( A[I,*,J] ) / 4.
ENDFOR
ENDFOR
RESTRICTIONS:
Dimension specified must be valid for the array passed; otherwise the
input array is returned as the output array.
PROCEDURE:
AVG(ARRAY) = TOTAL(ARRAY, /DOUBLE)/N_ELEMENTS(ARRAY) when called with
one parameter.
MODIFICATION HISTORY:
William Thompson Applied Research Corporation
July, 1986 8201 Corporate Drive
Landover, MD 20785
Converted to Version 2 July, 1990
Replace SUM call with TOTAL W. Landsman May, 1992
Converted to IDL V5.0 W. Landsman September 1997
Added /NAN keyword W. Landsman July 2000
Accept a scalar input value W. Landsman/jimm@berkeley November 2000
Internal calculations always in double precision W. Landsman March 2002
Return NAN if all values in array are NAN W. Landsman April 2002
Fixed coding bug if all values in array are NAN W. Landsman Jan 2004
(See astrolib/pro/avg.pro)
NAME:
BARYVEL
PURPOSE:
Calculates heliocentric and barycentric velocity components of Earth.
EXPLANATION:
BARYVEL takes into account the Earth-Moon motion, and is useful for
radial velocity work to an accuracy of ~1 m/s.
CALLING SEQUENCE:
BARYVEL, dje, deq, dvelh, dvelb, [ JPL = ]
INPUTS:
DJE - (scalar) Julian ephemeris date.
DEQ - (scalar) epoch of mean equinox of dvelh and dvelb. If deq=0
then deq is assumed to be equal to dje.
OUTPUTS:
DVELH: (vector(3)) heliocentric velocity component. in km/s
DVELB: (vector(3)) barycentric velocity component. in km/s
The 3-vectors DVELH and DVELB are given in a right-handed coordinate
system with the +X axis toward the Vernal Equinox, and +Z axis
toward the celestial pole.
OPTIONAL KEYWORD SET:
JPL - if /JPL set, then BARYVEL will call the procedure JPLEPHINTERP
to compute the Earth velocity using the full JPL ephemeris.
The JPL ephemeris FITS file JPLEPH.405 must exist in either the
current directory, or in the directory specified by the
environment variable ASTRO_DATA. Alternatively, the JPL keyword
can be set to the full path and name of the ephemeris file.
A copy of the JPL ephemeris FITS file is available in
http://idlastro.gsfc.nasa.gov/ftp/data/
PROCEDURES CALLED:
Function PREMAT() -- computes precession matrix
JPLEPHREAD, JPLEPHINTERP, TDB2TDT - if /JPL keyword is set
NOTES:
Algorithm taken from FORTRAN program of Stumpff (1980, A&A Suppl, 41,1)
Stumpf claimed an accuracy of 42 cm/s for the velocity. A
comparison with the JPL FORTRAN planetary ephemeris program PLEPH
found agreement to within about 65 cm/s between 1986 and 1994
If /JPL is set (using JPLEPH.405 ephemeris file) then velocities are
given in the ICRS system; otherwise in the FK4 system.
EXAMPLE:
Compute the radial velocity of the Earth toward Altair on 15-Feb-1994
using both the original Stumpf algorithm and the JPL ephemeris
IDL> jdcnv, 1994, 2, 15, 0, jd ;==> JD = 2449398.5
IDL> baryvel, jd, 2000, vh, vb ;Original algorithm
==> vh = [-17.07243, -22.81121, -9.889315] ;Heliocentric km/s
==> vb = [-17.08083, -22.80471, -9.886582] ;Barycentric km/s
IDL> baryvel, jd, 2000, vh, vb, /jpl ;JPL ephemeris
==> vh = [-17.07236, -22.81126, -9.889419] ;Heliocentric km/s
==> vb = [-17.08083, -22.80484, -9.886409] ;Barycentric km/s
IDL> ra = ten(19,50,46.77)*15/!RADEG ;RA in radians
IDL> dec = ten(08,52,3.5)/!RADEG ;Dec in radians
IDL> v = vb[0]*cos(dec)*cos(ra) + $ ;Project velocity toward star
vb[1]*cos(dec)*sin(ra) + vb[2]*sin(dec)
REVISION HISTORY:
Jeff Valenti, U.C. Berkeley Translated BARVEL.FOR to IDL.
W. Landsman, Cleaned up program sent by Chris McCarthy (SfSU) June 1994
Converted to IDL V5.0 W. Landsman September 1997
Added /JPL keyword W. Landsman July 2001
Documentation update W. Landsman Dec 2005
(See astrolib/pro/baryvel.pro)
NAME:
BIWEIGHT_MEAN
PURPOSE:
Calculate the center and dispersion (like mean and sigma) of a
distribution using bisquare weighting.
CALLING SEQUENCE:
Mean = BIWEIGHT_MEAN( Vector, [ Sigma, Weights ] )
INPUTS:
Vector = Distribution in vector form
OUTPUT:
Mean - The location of the center.
OPTIONAL OUTPUT ARGUMENTS:
Sigma = An outlier-resistant measure of the dispersion about the
center, analogous to the standard deviation.
Weights = The weights applied to the data in the last iteration,
floating point vector
NOTES:
Since a sample mean scaled by sigma/sqrt(N), has a Student's T
distribution, the half-width of the 95% confidence interval for
the sample mean can be determined as follows:
ABS( T_CVF( .975, .7*(N-1) )*SIGMA/SQRT(N) )
where N = number of points, and 0.975 = 1 - (1 - 0.95)/2.
PROCEDURES USED:
ROBUST_SIGMA()
REVISION HISTORY
Written, H. Freudenreich, STX, 12/89
Modified 2/94, H.T.F.: use a biweighted standard deviation rather than
median absolute deviation.
Modified 2/94, H.T.F.: use the fractional change in SIGMA as the
convergence criterion rather than the change in center/SIGMA.
Modified May 2002 Use MEDIAN(/EVEN)
Modified October 2002, Faster computation of weights
Corrected documentation on 95% confidence interval of mean
P.Broos/W. Landsman July 2003
(See astrolib/pro/biweight_mean.pro)
NAME: BLINK PURPOSE: To allow the user to alternatively examine two or more windows within a single window. CALLING SEQUENCE: BLINK, Wndw [, T] INPUTS: Wndw A vector containing the indices of the windows to blink. T The time to wait, in seconds, between blinks. This is optional and set to 1 if not present. OUTPUTS: None. PROCEDURE: The images contained in the windows given are written to a pixmap. The contents of the the windows are copied to a display window, in order, until a key is struck. EXAMPLE: Blink windows 0 and 2 with a wait time of 3 seconds IDL> blink, [0,2], 3 MODIFICATION HISTORY: Written by Michael R. Greason, STX, 2 May 1990. Allow different size windows Wayne Landsman August, 1991 Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/blink.pro)
NAME:
BLKSHIFT
AUTHOR:
Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
[email protected]
PURPOSE:
Shift a block of data to a new position in a file (possibly overlapping)
CALLING SEQUENCE:
BLKSHIFT, UNIT, POS, [ DELTA, TO=TO, /NOZERO, ERRMSG=ERRMSG,
BUFFERSIZE=BUFFERSIZE ]
DESCRIPTION:
BLKSHIFT moves a block of data forward or backward, to a new
position in a data file. The old and new positions of the block
can overlap safely.
The new position can be specified with either the DELTA parameter,
which gives the number of bytes to move forward (positive delta) or
backward (negative delta); or the TO keyword, which give the new
absolute starting position of the block.
The block can be moved beyond the current end of file point, in
which case the intervening gap is filled with zeros (optionally).
The gap left at the old position of the block is also optionally
zero-filled. If a set of data up to the end of the file is being
moved forward (thus making the file smaller) then
the file is truncated at the new end.using TRUNCATE_LUN.
INPUTS:
UNIT - a logical unit number, opened for reading and writing.
POS - POS[0] is the position of the block in the file, in bytes,
before moving. POS[1], if present, is the size of the block
in bytes. If POS[1] is not given, then the block is from
POS[0] to the end of the file.
DELTA - the (optional) offset in bytes between the old and new
positions, from the start of the block. Positive values
indicate moving the data forward (toward the end of file),
and negative values indicate moving the data backward
(toward the beginning of the file). One of DELTA and TO
must be specified; DELTA overrides the TO keyword.
Attempts to move the block beyond the end of the file will
succeed. A block can never be moved beyond the beginning
of the file; it will be moved to the beginning instead.
KEYWORD PARAMETERS:
TO - the absolute file offset in bytes for the new start of the
block. One of DELTA and TO must be specified; DELTA
overrides the TO keyword.
/NOZERO - if set, then newly created gaps will not be explicitly
zeroed. Note that in same systems (e.g. MacOS) the gaps will
always be zeroed whether or not /NOZERO is set.
ERRMSG - If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors
are encountered, then a null string is returned.
BLKSHIFT, UNIT, POS, DElTA, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
BUFFERSIZE - the maximum buffer size for transfers, in bytes.
Larger values of this keyword impose larger memory
requirements on the application; smaller values will
lead to more transfer operations.
Default: 32768 (bytes)
MODIFICATION HISTORY:
Written, CM, Apr 2000
Documented and re-written, CM, 20 Jul 2000
Renamed from FXSHIFT to BLKSHIFT, CM, 21 Jul 2000
Documentation, CM, 12 Dec 2002
Truncate if moving data block forward from the end of file
using TRUNCATE_LUN W. Landsman Feb. 2005
Assume since V5.5, remove VMS support W. Landsman Sep 2006
Assume since V5.6, TRUNCATE_LUN available W. Landsman Sep 2006
MacOS can point beyond EOF W. Landsman Aug 2009
(See astrolib/pro/blkshift.pro)
NAME: BOOST_ARRAY PURPOSE: Append one array onto a destination array EXPLANATION: Add array APPEND to array DESTINATION, allowing the dimensions of DESTINATION to adjust to accommodate it. If both input arrays have the same number of dimensions, then the output array will have one additional dimension. Otherwise, the last dimension of DESTINATION will be incremented by one. CATEGORY: Utility CALLING SEQUENCE: BOOST_ARRAY, DESTINATION, APPEND INPUT: DESTINATION = Array to be expanded. APPEND = Array to append to DESTINATION. OUTPUTS: DESTINATION = Expanded output array. RESTRICTIONS: DESTINATION and APPEND have to be either both of type string or both of numerical types. APPEND cannot have more dimensions than DESTINATION. MODIFICATION HISTOBY: Written Aug'88 (DMZ, ARC) Modified Sep'89 to handle byte arrays (DMZ) Modifed to version 2, Paul Hick (ARC), Feb 1991 Removed restriction to 2D arrays, William Thompson (ARC), Feb 1992. Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/boost_array.pro)
NAME:
BOXAVE
PURPOSE:
Box-average a 1 or 2 dimensional array.
EXPLANATION:
This procedure differs from the intrinsic REBIN function in the follow
2 ways:
(1) the box size parameter is specified rather than the output
array size
(2) for INTEGER arrays, BOXAVE computes intermediate steps using REAL*4
(or REAL*8 for 64bit integers) arithmetic. This is
considerably slower than REBIN but avoids integer truncation
CALLING SEQUENCE:
result = BOXAVE( Array, Xsize,[ Ysize ] )
INPUTS:
ARRAY - Two dimensional input Array to be box-averaged. Array may be
one or 2 dimensions and of any type except character.
OPTIONAL INPUTS:
XSIZE - Size of box in the X direction, over which the array is to
be averaged. If omitted, program will prompt for this
parameter.
YSIZE - For 2 dimensional arrays, the box size in the Y direction.
If omitted, then the box size in the X and Y directions are
assumed to be equal
OUTPUT:
RESULT - Output array after box averaging. If the input array has
dimensions XDIM by YDIM, then RESULT has dimensions
XDIM/NBOX by YDIM/NBOX. The type of RESULT is the same as
the input array. However, the averaging is always computed
using REAL arithmetic, so that the calculation should be exact.
If the box size did not exactly divide the input array, then
then not all of the input array will be boxaveraged.
PROCEDURE:
BOXAVE boxaverages all points simultaneously using vector subscripting
NOTES:
If im_int is a 512 x 512 integer array, then the two statements
IDL> im = fix(round(rebin(float(im_int), 128, 128)))
IDL> im = boxave( im_int,4)
give equivalent results. The use of REBIN is faster, but BOXAVE is
is less demanding on virtual memory, since one does not need to make
a floating point copy of the entire array.
REVISION HISTORY:
Written, W. Landsman, October 1986
Call REBIN for REAL*4 and REAL*8 input arrays, W. Landsman Jan, 1992
Removed /NOZERO in output array definition W. Landsman 1995
Fixed occasional integer overflow problem W. Landsman Sep. 1995
Allow unsigned data types W. Landsman Jan. 2000
Assume since V5.4, Allow 64bit integers W. Landsman Apr 2006
(See astrolib/pro/boxave.pro)
NAME:
BPRECESS
PURPOSE:
Precess positions from J2000.0 (FK5) to B1950.0 (FK4)
EXPLANATION:
Calculates the mean place of a star at B1950.0 on the FK4 system from
the mean place at J2000.0 on the FK5 system.
CALLING SEQUENCE:
bprecess, ra, dec, ra_1950, dec_1950, [ MU_RADEC = , PARALLAX =
RAD_VEL =, EPOCH = ]
INPUTS:
RA,DEC - Input J2000 right ascension and declination in *degrees*.
Scalar or N element vector
OUTPUTS:
RA_1950, DEC_1950 - The corresponding B1950 right ascension and
declination in *degrees*. Same number of elements as
RA,DEC but always double precision.
OPTIONAL INPUT-OUTPUT KEYWORDS
MU_RADEC - 2xN element double precision vector containing the proper
motion in seconds of arc per tropical *century* in right
ascension and declination.
PARALLAX - N_element vector giving stellar parallax (seconds of arc)
RAD_VEL - N_element vector giving radial velocity in km/s
The values of MU_RADEC, PARALLAX, and RADVEL will all be modified
upon output to contain the values of these quantities in the
B1950 system. The parallax and radial velocity will have a very
minor influence on the B1950 position.
EPOCH - scalar giving epoch of original observations, default 2000.0d
This keyword value is only used if the MU_RADEC keyword is not set.
NOTES:
The algorithm is taken from the Explanatory Supplement to the
Astronomical Almanac 1992, page 186.
Also see Aoki et al (1983), A&A, 128,263
BPRECESS distinguishes between the following two cases:
(1) The proper motion is known and non-zero
(2) the proper motion is unknown or known to be exactly zero (i.e.
extragalactic radio sources). In this case, the reverse of
the algorithm in Appendix 2 of Aoki et al. (1983) is used to
ensure that the output proper motion is exactly zero. Better
precision can be achieved in this case by inputting the EPOCH
of the original observations.
The error in using the IDL procedure PRECESS for converting between
B1950 and J1950 can be up to 12", mainly in right ascension. If
better accuracy than this is needed then BPRECESS should be used.
An unsystematic comparison of BPRECESS with the IPAC precession
routine (http://nedwww.ipac.caltech.edu/forms/calculator.html) always
gives differences less than 0.15".
EXAMPLE:
The SAO2000 catalogue gives the J2000 position and proper motion for
the star HD 119288. Find the B1950 position.
RA(2000) = 13h 42m 12.740s Dec(2000) = 8d 23' 17.69''
Mu(RA) = -.0257 s/yr Mu(Dec) = -.090 ''/yr
IDL> mu_radec = 100D* [ -15D*.0257, -0.090 ]
IDL> ra = ten(13, 42, 12.740)*15.D
IDL> dec = ten(8, 23, 17.69)
IDL> bprecess, ra, dec, ra1950, dec1950, mu_radec = mu_radec
IDL> print, adstring(ra1950, dec1950,2)
===> 13h 39m 44.526s +08d 38' 28.63"
REVISION HISTORY:
Written, W. Landsman October, 1992
Vectorized, W. Landsman February, 1994
Treat case where proper motion not known or exactly zero November 1994
Handling of arrays larger than 32767 Lars L. Christensen, march, 1995
Fixed bug where A term not initialized for vector input
W. Landsman February 2000
Use V6.0 notation W. Landsman Mar 2011
(See astrolib/pro/bprecess.pro)
NAME:
BREAK_PATH()
PURPOSE:
Breaks up a path string into its component directories.
CALLING SEQUENCE:
Result = BREAK_PATH( PATHS [ /NoCurrent])
INPUTS:
PATHS = A string containing one or more directory paths. The
individual paths are separated by commas, although in UNIX,
colons can also be used. In other words, PATHS has the same
format as !PATH, except that commas can be used as a separator
regardless of operating system.
A leading $ can be used in any path to signal that what follows
is an environmental variable, but the $ is not necessary.
Environmental variables can themselves contain multiple paths.
OUTPUT:
The result of the function is a string array of directories.
Unless the NOCURRENT keyword is set, the first element of the array is
always the null string, representing the current directory. All the
other directories will end in the correct separator character for the
current operating system.
OPTIONAL INPUT KEYWORD:
/NOCURRENT = If set, then the current directory (represented by
the null string) will not automatically be prepended to the
output.
PROCEDURE CALLS:
None.
REVISION HISTORY:
Version 1, William Thompson, GSFC, 6 May 1993.
Added IDL for Windows compatibility.
Version 2, William Thompson, GSFC, 16 May 1995
Added keyword NOCURRENT
Version 3, William Thompson, GSFC, 29 August 1995
Modified to use OS_FAMILY
Version 4, Zarro, GSFC, 4 August 1997
Added trim to input
Fix directory character on Macintosh system A. Ferro February 2000
Use STRSPLIT instead of STR_SEP() W. Landsman July 2002
Remove VMS support W. Landsman September 2006
(See astrolib/pro/break_path.pro)
NAME:
BSORT
PURPOSE:
Function to sort data into ascending order, like a simple bubble sort.
EXPLANATION:
Original subscript order is maintained when values are equal (FIFO).
(This differs from the IDL SORT routine alone, which may rearrange
order for equal values)
A faster algorithm (radix sort) for numeric data is available at
http://idldatapoint.com/2012/04/19/an-lsd-radix-sort-algorithm-in-idl/
CALLING SEQUENCE:
result = bsort( array, [ asort, /INFO, /REVERSE ] )
INPUT:
Array - array to be sorted
OUTPUT:
result - sort subscripts are returned as function value
OPTIONAL OUTPUT:
Asort - sorted array
OPTIONAL KEYWORD INPUTS:
/REVERSE - if this keyword is set, and non-zero, then data is sorted
in descending order instead of ascending order.
/INFO = optional keyword to cause brief message about # equal values.
HISTORY
written by F. Varosi Oct.90:
uses WHERE to find equal clumps, instead of looping with IF ( EQ ).
compatible with string arrays, test for degenerate array
20-MAY-1991 JKF/ACC via T AKE- return indexes if the array to
be sorted has all equal values.
Aug - 91 Added REVERSE keyword W. Landsman
Always return type LONG W. Landsman August 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/bsort.pro)
NAME:
CALZ_UNRED
PURPOSE:
Deredden a galaxy spectrum using the Calzetti et al. (2000) recipe
EXPLANATION:
Calzetti et al. (2000, ApJ 533, 682) developed a recipe for dereddening
the spectra of galaxies where massive stars dominate the radiation output,
valid between 0.12 to 2.2 microns. (CALZ_UNRED extrapolates between
0.12 and 0.0912 microns.)
CALLING SEQUENCE:
CALZ_UNRED, wave, flux, ebv, [ funred, R_V = ]
INPUT:
WAVE - wavelength vector (Angstroms)
FLUX - calibrated flux vector, same number of elements as WAVE
If only 3 parameters are supplied, then this vector will
updated on output to contain the dereddened flux.
EBV - color excess E(B-V), scalar. If a negative EBV is supplied,
then fluxes will be reddened rather than deredenned.
Note that the supplied color excess should be that derived for
the stellar continuum, EBV(stars), which is related to the
reddening derived from the gas, EBV(gas), via the Balmer
decrement by EBV(stars) = 0.44*EBV(gas)
OUTPUT:
FUNRED - unreddened flux vector, same units and number of elements
as FLUX. FUNRED values will be zeroed outside valid domain
Calz_unred (0.0912 - 2.2 microns).
OPTIONAL INPUT KEYWORD:
R_V - Ratio of total to selective extinction, default = 4.05.
Calzetti et al. (2000) estimate R_V = 4.05 +/- 0.80 from optical
-IR observations of 4 starbursts.
EXAMPLE:
Estimate how a flat galaxy spectrum (in wavelength) between 1200 A
and 3200 A is altered by a reddening of E(B-V) = 0.1.
IDL> w = 1200 + findgen(40)*50 ;Create a wavelength vector
IDL> f = w*0 + 1 ;Create a "flat" flux vector
IDL> calz_unred, w, f, -0.1, fnew ;Redden (negative E(B-V)) flux vector
IDL> plot,w,fnew
NOTES:
Use the 4 parameter calling sequence if you wish to save the
original flux vector.
PROCEDURE CALLS:
POLY()
REVISION HISTORY:
Written W. Landsman Raytheon ITSS December, 2000
(See astrolib/pro/calz_unred.pro)
NAME:
CCM_UNRED
PURPOSE:
Deredden a flux vector using the CCM 1989 parameterization
EXPLANATION:
The reddening curve is that of Cardelli, Clayton, and Mathis (1989 ApJ.
345, 245), including the update for the near-UV given by O'Donnell
(1994, ApJ, 422, 158). Parameterization is valid from the IR to the
far-UV (3.5 microns to 0.1 microns).
Users might wish to consider using the alternate procedure FM_UNRED
which uses the extinction curve of Fitzpatrick (1999).
CALLING SEQUENCE:
CCM_UNRED, wave, flux, ebv, funred, [ R_V = ]
or
CCM_UNRED, wave, flux, ebv, [ R_V = ]
INPUT:
WAVE - wavelength vector (Angstroms)
FLUX - calibrated flux vector, same number of elements as WAVE
If only 3 parameters are supplied, then this vector will
updated on output to contain the dereddened flux.
EBV - color excess E(B-V), scalar. If a negative EBV is supplied,
then fluxes will be reddened rather than deredenned.
OUTPUT:
FUNRED - unreddened flux vector, same units and number of elements
as FLUX
OPTIONAL INPUT KEYWORD
R_V - scalar specifying the ratio of total selective extinction
R(V) = A(V) / E(B - V). If not specified, then R_V = 3.1
Extreme values of R(V) range from 2.75 to 5.3
EXAMPLE:
Determine how a flat spectrum (in wavelength) between 1200 A and 3200 A
is altered by a reddening of E(B-V) = 0.1. Assume an "average"
reddening for the diffuse interstellar medium (R(V) = 3.1)
IDL> w = 1200 + findgen(40)*50 ;Create a wavelength vector
IDL> f = w*0 + 1 ;Create a "flat" flux vector
IDL> ccm_unred, w, f, -0.1, fnew ;Redden (negative E(B-V)) flux vector
IDL> plot,w,fnew
NOTES:
(1) The CCM curve shows good agreement with the Savage & Mathis (1979)
ultraviolet curve shortward of 1400 A, but is probably
preferable between 1200 and 1400 A.
(2) Many sightlines with peculiar ultraviolet interstellar extinction
can be represented with a CCM curve, if the proper value of
R(V) is supplied.
(3) Curve is extrapolated between 912 and 1000 A as suggested by
Longo et al. (1989, ApJ, 339,474)
(4) Use the 4 parameter calling sequence if you wish to save the
original flux vector.
(5) Valencic et al. (2004, ApJ, 616, 912) revise the ultraviolet CCM
curve (3.3 -- 8.0 um-1). But since their revised curve does
not connect smoothly with longer and shorter wavelengths, it is
not included here.
REVISION HISTORY:
Written W. Landsman Hughes/STX January, 1992
Extrapolate curve for wavelengths between 900 and 1000 A Dec. 1993
Use updated coefficients for near-UV from O'Donnell Feb 1994
Allow 3 parameter calling sequence April 1998
Converted to IDLV5.0 April 1998
(See astrolib/pro/ccm_unred.pro)
NAME:
CHECKSUM32
PURPOSE:
To compute the 32bit checksum of an array (ones-complement arithmetic)
EXPLANATION:
The 32bit checksum is adopted in the FITS Checksum convention
http://heasarc.gsfc.nasa.gov/docs/heasarc/fits/checksum.html
CALLING SEQUENCE:
CHECKSUM32, array, checksum, [/FROM_IEEE, /NoSAVE]
INPUTS:
array - any numeric idl array. If the number of bytes in the array is
not a multiple of four then it is padded with zeros internally
(the array is returned unchanged). Convert a string array
(e.g. a FITS header) to bytes prior to calling CHECKSUM32.
OUTPUTS:
checksum - unsigned long scalar, giving sum of array elements using
ones-complement arithmetic
OPTIONAL INPUT KEYWORD:
/FROM_IEEE - If this keyword is set, then the input is assumed to be in
big endian format (e.g. an untranslated FITS array). This keyword
only has an effect on little endian machines (e.g. Linux boxes).
/NoSAVE - if set, then the input array is not saved upon exiting. Use
the /NoSave keyword to save time if the input array is not needed
in further computations.
METHOD:
Uses TOTAL() to sum the array into a double precision variable. The
overflow bits beyond 2^32 are then shifted back to the least significant
bits. Due to the limited precision of a DOUBLE variable, the summing
is done in chunks determined by MACHAR(). Adapted from FORTRAN code in
heasarc.gsfc.nasa.gov/docs/heasarc/ofwg/docs/general/checksum/node30.html
Could probably be done in a cleverer way (similar to the C
implementation) but then the array-oriented TOTAL() function could not
be used.
RESTRICTIONS:
(1) Not valid for object or pointer data types
EXAMPLE:
Find the 32 bit checksum of the array x = findgen(35)
IDL> checksum32, x, s ===> s = 2920022024
FUNCTION CALLED:
HOST_TO_IEEE, IS_IEEE_BIG(), N_BYTES()
MODIFICATION HISTORY:
Written W. Landsman June 2001
Work correctly on little endian machines, added /FROM_IEEE and /NoSave
W. Landsman November 2002
Pad with zeros when array size not a multiple of 4 W.Landsman Aug 2003
Always copy to new array, somewhat slower but more robust algorithm
especially for Linux boxes W. Landsman Sep. 2004
Sep. 2004 update not implemented correctly (sigh) W. Landsman Dec 2004
No need to byteswap 4 byte datatypes on little endian W. L. May 2009
Use /INTEGER keyword to TOTAL() function W.L. June 2009
(See astrolib/pro/checksum32.pro)
NAME:
CHECK_FITS
PURPOSE:
Check that keywords in a FITS header array match the associated data
EXPLANATION:
Given a FITS array IM, and a associated FITS header HDR, this
procedure will check that
(1) HDR is a string array, and IM is defined and numeric
(2) The NAXISi values in HDR are appropriate to the dimensions
of IM
(3) The BITPIX value in HDR is appropriate to the datatype of IM
If the /UPDATE keyword is present, then the FITS header will be
modified, if necessary, to force agreement with the image array
CALLING SEQUENCE:
check_FITS, im, hdr, [ dimen, idltype, /UPDATE, /NOTYPE, /SILENT
ERRMSG = ]'
INPUT PARAMETERS:
IM - FITS array, e.g. as read by READFITS
HDR - FITS header (string array) associated with IM
OPTIONAL OUTPUTS:
dimen - vector containing actual array dimensions
idltype- data type of the FITS array as specified in the IDL SIZE
function (1 for BYTE, 2 for INTEGER*2, 3 for INTEGER*4, etc.)
OPTIONAL KEYWORD INPUTS:
/NOTYPE - If this keyword is set, then only agreement of the array
dimensions with the FITS header are checked, and not the
data type.
/UPDATE - If this keyword is set then the BITPIX, NAXIS and NAXISi
FITS keywords will be updated to agree with the array
/FITS, /SDAS - these are obsolete keywords that now do nothing
/SILENT - If keyword is set and nonzero, the informational messages
will not be printed
OPTIONAL KEYWORD OUTPUT:
ERRMSG = If this keyword is present, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned.
PROCEDURE:
Program checks the NAXIS and NAXISi keywords in the header to
see if they match the image array dimensions, and checks whether
the BITPIX keyword agrees with the array type.
PROCEDURE CALLS:
FXADDPAR, FXPAR(), SXDELPAR
MODIFICATION HISTORY:
Written, December 1991 W. Landsman Hughes/STX to replace CHKIMHD
No error returned if NAXIS=0 and IM is a scalar W. Landsman Feb 93
Fixed bug for REAL*8 STSDAS data W. Landsman July 93
Make sure NAXIS agrees with NAXISi W. Landsman October 93
Converted to IDL V5.0 W. Landsman September 1997
Allow unsigned data types W. Landsman December 1999
Allow BZERO = 0 for unsigned data types W. Landsman January 2000
Added ERRMSG keyword, W. Landsman February 2000
Use FXADDPAR to put NAXISi in proper order W. Landsman August 2000
Improper FXADDPAR call for DATATYPE keyword W. Landsman December 2000
Remove explicit setting of obsolete !err W. Landsman February 2004
Remove SDAS support W. Landsman November 2006
Fix dimension errors introduced Nov 2006
Work again for null arrays W. Landsman/E. Hivon May 2007
Use V6.0 notation W.L. Feb. 2011
(See astrolib/pro/check_fits.pro)
NAME:
CIC
PURPOSE:
Interpolate an irregularly sampled field using Cloud in Cell method
EXPLANATION:
This function interpolates an irregularly sampled field to a
regular grid using Cloud In Cell (nearest grid point gets
weight 1-dngp, point on other side gets weight dngp, where
dngp is the distance to the nearest grid point in units of the
cell size).
CATEGORY:
Mathematical functions, Interpolation
CALLING SEQUENCE:
Result = CIC, VALUE, POSX, NX[, POSY, NY, POSZ, NZ,
AVERAGE = average, WRAPAROUND = wraparound,
ISOLATED = isolated, NO_MESSAGE = no_message]
INPUTS:
VALUE: Array of sample weights (field values). For e.g. a
temperature field this would be the temperature and the
keyword AVERAGE should be set. For e.g. a density field
this could be either the particle mass (AVERAGE should
not be set) or the density (AVERAGE should be set).
POSX: Array of X coordinates of field samples, unit indices: [0,NX>.
NX: Desired number of grid points in X-direction.
OPTIONAL INPUTS:
POSY: Array of Y coordinates of field samples, unit indices: [0,NY>.
NY: Desired number of grid points in Y-direction.
POSZ: Array of Z coordinates of field samples, unit indices: [0,NZ>.
NZ: Desired number of grid points in Z-direction.
KEYWORD PARAMETERS:
AVERAGE: Set this keyword if the nodes contain field samples
(e.g. a temperature field). The value at each grid
point will then be the weighted average of all the
samples allocated to it. If this keyword is not
set, the value at each grid point will be the
weighted sum of all the nodes allocated to it
(e.g. for a density field from a distribution of
particles). (D=0).
WRAPAROUND: Set this keyword if you want the first grid point
to contain samples of both sides of the volume
(see below).
ISOLATED: Set this keyword if the data is isolated, i.e. not
periodic. In that case total `mass' is not conserved.
This keyword cannot be used in combination with the
keyword WRAPAROUND.
NO_MESSAGE: Suppress informational messages.
Example of default allocation of nearest grid points: n0=4, *=gridpoint.
0 1 2 3 Index of gridpoints
* * * * Grid points
|---|---|---|---| Range allocated to gridpoints ([0.0,1.0> --> 0, etc.)
0 1 2 3 4 posx
Example of ngp allocation for WRAPAROUND: n0=4, *=gridpoint.
0 1 2 3 Index of gridpoints
* * * * Grid points
|---|---|---|---|-- Range allocated to gridpoints ([0.5,1.5> --> 1, etc.)
0 1 2 3 4=0 posx
OUTPUTS:
Prints that a CIC interpolation is being performed of x
samples to y grid points, unless NO_MESSAGE is set.
RESTRICTIONS:
Field data is assumed to be periodic with the sampled volume
the basic cell, unless ISOLATED is set.
All input arrays must have the same dimensions.
Postition coordinates should be in `index units' of the
desired grid: POSX=[0,NX>, etc.
Keywords ISOLATED and WRAPAROUND cannot both be set.
PROCEDURE:
Nearest grid point is determined for each sample.
CIC weights are computed for each sample.
Samples are interpolated to the grid.
Grid point values are computed (sum or average of samples).
NOTES:
Use tsc.pro for a higher-order interpolation scheme, ngp.pro for a lower
order interpolation scheme. A standard reference for these
interpolation methods is: R.W. Hockney and J.W. Eastwood, Computer
Simulations Using Particles (New York: McGraw-Hill, 1981).
EXAMPLE:
nx=20
ny=10
posx=randomu(s,1000)
posy=randomu(s,1000)
value=posx^2+posy^2
field=cic(value,posx*nx,nx,posy*ny,ny,/average)
surface,field,/lego
MODIFICATION HISTORY:
Written by Joop Schaye, Feb 1999.
Avoid integer overflow for large dimensions P.Riley/W.Landsman Dec. 1999
(See astrolib/pro/cic.pro)
NAME:
CIRRANGE
PURPOSE:
To force an angle into the range 0 <= ang < 360.
CALLING SEQUENCE:
CIRRANGE, ang, [/RADIANS]
INPUTS/OUTPUT:
ang - The angle to modify, in degrees. This parameter is
changed by this procedure. Can be a scalar or vector.
The type of ANG is always converted to double precision
on output.
OPTIONAL INPUT KEYWORDS:
/RADIANS - If present and non-zero, the angle is specified in
radians rather than degrees. It is forced into the range
0 <= ang < 2 PI.
PROCEDURE:
The angle is transformed between -360 and 360 using the MOD operator.
Negative values (if any) are then transformed between 0 and 360
MODIFICATION HISTORY:
Written by Michael R. Greason, Hughes STX, 10 February 1994.
Get rid of WHILE loop, W. Landsman, Hughes STX, May 1996
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/cirrange.pro)
NAME:
CLEANPLOT
PURPOSE:
Reset all plotting system variables (!P,!X,!Y,!Z) to their default values
EXPLANATION:
Reset all system variables (!P,!X,!Y,!Z) which are set by the user
and which affect plotting to their default values.
CALLING SEQUENCE:
Cleanplot, [ /Silent, /ShowOnly]
INPUTS:
None
OPTIONAL KEYWORD INPUT:
/SHOWONLY - If set, then CLEANPLOT will display the plotting system
variables with nondefault values, but it will not reset them.
/SILENT - If set, then CLEANPLOT will not display a message giving the
the system variables tags being reset. One cannot set
both /SILENT and /SHOWONLY
OUTPUTS:
None
SIDE EFFECTS:
The system variables that concern plotting are reset to their default
values. A message is output for each variable changed.
The !P.CLIP and CRANGE, S, WINDOW, and REGION fields of the
!X, !Y, and !Z system variables are not checked since these are
set by the graphics device and not by the user.
PROCEDURE:
This does NOT reset the plotting device.
This does not change any system variables that don't control plotting.
RESTRICTIONS:
If user default values for !P, !X, !Y and !Z are different from
the defaults adopted below, user should change P_old etc accordingly
MODIFICATION HISTORY:
Written IDL Version 2.3.0 W. Landsman & K. Venkatakrishna May '92
Handle new system variables in V3.0.0 W. Landsman Dec 92
Assume user has at least V3.0.0 W. Landsman August 95
V5.0 has 60 instead of 30 TICKV values W. Landsman Sep. 97
Change !D.N_COLORS to !D.TABLE_SIZE for 24 bit displays
W. Landsman April 1998
Added silent keyword to supress output & modified X_old to
handle the new !X and !Y tags in IDL 5.4 S. Penton July 2000
Test for visual depth if > V5.1 W. Landsman July 2000
Macs can report a visual depth of 32 W. Landsman March 2001
Call device,get_visual_depth only for device which allow it
W. Landsman June 2001
Default !P.color is 16777215 for 16 bit systems
W. Landsman/M. Hadfield November 2001
Added ShowOnly keyword W. Landsman April 2002
Use V6.0 notation W. Landsman April 2011
(See astrolib/pro/cleanplot.pro)
NAME:
CNTRD
PURPOSE:
Compute the centroid of a star using a derivative search
EXPLANATION:
CNTRD uses an early DAOPHOT "FIND" centroid algorithm by locating the
position where the X and Y derivatives go to zero. This is usually a
more "robust" determination than a "center of mass" or fitting a 2d
Gaussian if the wings in one direction are affected by the presence
of a neighboring star.
CALLING SEQUENCE:
CNTRD, img, x, y, xcen, ycen, [ fwhm , /KEEPCENTER, /SILENT, /DEBUG
EXTENDBOX = ]
INPUTS:
IMG - Two dimensional image array
X,Y - Scalar or vector integers giving approximate integer stellar
center
OPTIONAL INPUT:
FWHM - floating scalar; Centroid is computed using a box of half
width equal to 1.5 sigma = 0.637* FWHM. CNTRD will prompt
for FWHM if not supplied
OUTPUTS:
XCEN - the computed X centroid position, same number of points as X
YCEN - computed Y centroid position, same number of points as Y,
floating point
Values for XCEN and YCEN will not be computed if the computed
centroid falls outside of the box, or if the computed derivatives
are non-decreasing. If the centroid cannot be computed, then a
message is displayed and XCEN and YCEN are set to -1.
OPTIONAL OUTPUT KEYWORDS:
/SILENT - Normally CNTRD prints an error message if it is unable
to compute the centroid. Set /SILENT to suppress this.
/DEBUG - If this keyword is set, then CNTRD will display the subarray
it is using to compute the centroid.
EXTENDBOX = {non-negative positive integer}. CNTRD searches a box with
a half width equal to 1.5 sigma = 0.637* FWHM to find the
maximum pixel. To search a larger area, set EXTENDBOX to
the number of pixels to enlarge the half-width of the box.
Default is 0; prior to June 2004, the default was EXTENDBOX= 3
/KeepCenter = By default, CNTRD finds the maximum pixel in a box
centered on the input X,Y coordinates, and then extracts a new
box about this maximum pixel. Set the /KeepCenter keyword
to skip then step of finding the maximum pixel, and instead use
a box centered on the input X,Y coordinates.
PROCEDURE:
Maximum pixel within distance from input pixel X, Y determined
from FHWM is found and used as the center of a square, within
which the centroid is computed as the value (XCEN,YCEN) at which
the derivatives of the partial sums of the input image over (y,x)
with respect to (x,y) = 0. In order to minimize contamination from
neighboring stars stars, a weighting factor W is defined as unity in
center, 0.5 at end, and linear in between
RESTRICTIONS:
(1) Does not recognize (bad) pixels. Use the procedure GCNTRD.PRO
in this situation.
(2) DAOPHOT now uses a newer algorithm (implemented in GCNTRD.PRO) in
which centroids are determined by fitting 1-d Gaussians to the
marginal distributions in the X and Y directions.
(3) The default behavior of CNTRD changed in June 2004 (from EXTENDBOX=3
to EXTENDBOX = 0).
(4) Stone (1989, AJ, 97, 1227) concludes that the derivative search
algorithm in CNTRD is not as effective (though faster) as a
Gaussian fit (used in GCNTRD.PRO).
MODIFICATION HISTORY:
Written 2/25/86, by J. K. Hill, S.A.S.C., following
algorithm used by P. Stetson in DAOPHOT.
Allowed input vectors G. Hennessy April, 1992
Fixed to prevent wrong answer if floating pt. X & Y supplied
W. Landsman March, 1993
Convert byte, integer subimages to float W. Landsman May 1995
Converted to IDL V5.0 W. Landsman September 1997
Better checking of edge of frame David Hogg October 2000
Avoid integer wraparound for unsigned arrays W.Landsman January 2001
Handle case where more than 1 pixel has maximum value W.L. July 2002
Added /KEEPCENTER, EXTENDBOX (with default = 0) keywords WL June 2004
Some errrors were returning X,Y = NaN rather than -1,-1 WL Aug 2010
(See astrolib/pro/cntrd.pro)
NAME:
COMPARE_STRUCT
PURPOSE:
Compare all matching tag names and return differences
EXPLANATION:
Compare all matching Tags names (except for "except_Tags")
between two structure arrays (may have different struct.definitions),
and return a structured List of fields found different.
The Exelis contrib library has a faster but less powerful procedure
struct_equal.pro, see
http://www.exelisvis.com/Default.aspx?tabid=1540&id=1175
CALLING SEQUENCE:
diff_List = compare_struct( struct_A, struct_B [ EXCEPT=, /BRIEF,
/FULL, /NaN, /RECUR_A, /RECUR_B )
INPUTS:
struct_A, struct_B : the two structure arrays to compare.
Struct_Name : for internal recursion use only.
OPTIONAL INPUT KEYWORDS:
EXCEPT = string array of Tag names to ignore (NOT to compare).
/BRIEF = number of differences found for each matching field
of two structures is printed.
/FULL = option to print even if zero differences found.
/NaN = if set, then tag values are considered equal if they
are both set to NaN
/RECUR_A = option to search for Tag names
in sub-structures of struct_A,
and then call compare_struct recursively
for those nested sub-structures.
/RECUR_B = search for sub-structures of struct_B,
and then call compare_struct recursively
for those nested sub-structures.
Note:
compare_struct is automatically called recursively
for those nested sub-structures in both struct_A and struct_B
(otherwise cannot take difference)
OUTPUT:
Returns a structure array describing differences found.
which can be examined using print,diff_List or help,/st,diff_List.
The tags are
TAG_NUM_A - the tag number in structure A
TAG_NUM_B - the tag number in structure B
FIELD - the tag name
NDIFF - number of differences (always 1 for a scalar tag).
PROCEDURE:
Match Tag names and then use where function on tags.
EXAMPLE:
Find the tags in the !X system variable which are changed after a
simple plot.
IDL> x = !X ;Save original values
IDL> plot, indgen(25) ;Make a simple plot
IDL> help,/str,compare_struct(x,!X) ;See how structure has changed
and one will see that the tags !X.crange and !X.S are changed
by the plot.
MODIFICATION HISTORY:
written 1990 Frank Varosi STX @ NASA/GSFC (using copy_struct)
modif Aug.90 by F.V. to check and compare same # of elements only.
Added /NaN keyword W. Landsman March 2004
Don't test string for NaN values W. Landsman March 2008
(See astrolib/pro/compare_struct.pro)
NAME:
CONCAT_DIR()
PURPOSE:
To concatenate directory and file names for current OS.
EXPLANATION:
The given file name is appended to the given directory name with the
format appropriate to the current operating system.
CALLING SEQUENCE:
result = concat_dir( directory, file)
INPUTS:
directory - the directory path (string)
file - the basic file name and extension (string)
can be an array of filenames.
OUTPUTS:
The function returns the concatenated string. If the file input
is a string array then the output will be a string array also.
EXAMPLES:
IDL> pixfile = concat_dir('$DIR_GIS_MODEL','pixels.dat')
IDL> file = ['f1.dat','f2.dat','f3.dat']
IDL> dir = '$DIR_NIS_CAL'
IDL>
RESTRICTIONS:
The version of CONCAT_DIR available at
http://sohowww.nascom.nasa.gov/solarsoft/gen/idl/system/concat_dir.pro
includes (mostly) additional VMS-specific keywords.
CATEGORY
Utilities, Strings
REVISION HISTORY:
Prev Hist. : Yohkoh routine by M. Morrison
Written : CDS version by C D Pike, RAL, 19/3/93
Version : Version 1 19/3/93
Documentation modified Nov-94 W. Landsman
Add V4.0 support for Windows W. Landsman Aug 95
Converted to IDL V5.0 W. Landsman September 1997
Changed loops to long integer W. Landsman December 1998
Added Mac support, translate Windows environment variables,
& treat case where dirname ends in '/' W. Landsman Feb. 2000
Assume since V5.5, remove VMS support W. Landsman Sep. 2006
(See astrolib/pro/concat_dir.pro)
NAME:
CONS_DEC
PURPOSE:
Obtain the X and Y coordinates of a line of constant declination
EXPLANATION:
Returns a set of Y pixels values, given an image with astrometry, and
either
(1) A set of X pixel values, and a scalar declination value, or
(2) A set of declination values, and a scalar X value
Form (1) can be used to find the (X,Y) values of a line of constant
declination. Form (2) can be used to find the Y positions of a set
declinations, along a line of constant X.
CALLING SEQUENCE:
Y = CONS_DEC( DEC, X, ASTR, [ ALPHA ])
INPUTS:
DEC - Declination value(s) in DEGREES (-!PI/2 < DEC < !PI/2).
If X is a vector, then DEC must be a scalar.
X - Specified X pixel value(s) for line of constant declination
If DEC is a vector, then X must be a scalar.
ASTR - Astrometry structure, as extracted from a FITS header by the
procedure EXTAST
OUTPUT:
Y - Computed set of Y pixel values. The number of Y values is the
same as either DEC or X, whichever is greater.
OPTIONAL OUTPUT:
ALPHA - the right ascensions (DEGREES) associated with the (X,Y) points
RESTRICTIONS:
Implemented only for the TANgent, SIN and CAR projections
NOTES:
The algorithm (and notation) is based on AIPS Memo 27 by Eric Greisen,
with modifications for a coordinate description (CD) matrix as
described in Paper II of Greisen & Calabretta (2002, A&A, 395, 1077).
These documents are available from
http://www.cv.nrao.edu/fits/documents/wcs/wcs.html
REVISION HISTORY:
Written, Wayne Landsman STX Co. April 1988
Use new astrometry structure, W. Landsman HSTX Jan. 1994
Use CD matrix, add SIN projection W. Landsman HSTX April, 1996
Converted to IDL V5.0 W. Landsman September 1997
Fix case where DEC is scalar, X is vector W. Landsman RITSS Feb. 2000
Fix possible sign error introduced Jan. 2000 W. Landsman May 2000
Work for the CARee' projection W. Landsman May 2003
(See astrolib/pro/cons_dec.pro)
NAME:
CONS_RA
PURPOSE:
Obtain the X and Y coordinates of a line of constant right ascension
EXPLANATION:
Return a set of X pixel values given an image with astrometry,
and either
(1) a set of Y pixel values, and a scalar right ascension (or
longitude), or
(2) a set of right ascension values, and a scalar Y value.
In usage (1), CONS_RA can be used to determine the (X,Y) values
of a line of constant right ascension. In usage (2), CONS_RA can
used to determine the X positions of specified RA values, along a
line of constant Y.
CALLING SEQUENCE:
X = CONS_RA( RA, Y, ASTR, [ DEC] )
INPUTS:
RA - Right Ascension value in DEGREES (0 < RA < 360.). If Y is a
vector, then RA must be a scalar
Y - Specified Y pixel value(s) for line of constant right ascension
If RA is a vector, then Y must be a scalar
ASTR - Astrometry structure as extracted from a FITS header by the
procedure EXTAST
OUTPUTS
X - Computed set of X pixel values. The number of elements of X
is the maximum of the number of elements of RA and Y.
OPTIONAL OUTPUT:
DEC - Computed set of declinations (in DEGREES) for X,Y, coordinates
NOTES:
The algorithm (and notation) is based on AIPS Memo 27 by Eric Greisen,
with modifications for a coordinate description (CD) matrix as
described in Paper II of Calabretta & Greisen (2002, A&A, 395, 1077).
These documents are available from
http://www.cv.nrao.edu/fits/documents/wcs/wcs.html
RESTRICTIONS:
Implemented only for the TANgent, SIN and CARtesian projections
REVISION HISTORY:
Written, Wayne Landsman STX Co. April, 1988
Algorithm adapted from AIPS memo No. 27 by Eric Greisen
New astrometry structure
Converted to IDL V5.0 W. Landsman September 1997
Added SIN projection W. Landsman January 2000
Fix possible sign error introduced Jan. 2000 W. Landsman May 2000
Work for the CARee' projection W. Landsman May 2003
For TAN projection ensure angles between -90 and 90 W. Landsman Jan 2008
(See astrolib/pro/cons_ra.pro)
NAME:
CONVOLVE
PURPOSE:
Convolution of an image with a Point Spread Function (PSF)
EXPLANATION:
The default is to compute the convolution using a product of
Fourier transforms (for speed).
The image is padded with zeros so that a large PSF does not
overlap one edge of the image with the opposite edge of the image.
This routine is now partially obsolete due to the introduction of the
intrinsic CONVOL_FFT() function in IDL 8.1
CALLING SEQUENCE:
imconv = convolve( image1, psf, FT_PSF = psf_FT )
or:
correl = convolve( image1, image2, /CORREL )
or:
correl = convolve( image, /AUTO )
INPUTS:
image = 2-D array (matrix) to be convolved with psf
psf = the Point Spread Function, (size < or = to size of image).
The PSF *must* be symmetric about the point
FLOOR((n_elements-1)/2), where n_elements is the number of
elements in each dimension. For Gaussian PSFs, the maximum
of the PSF must occur in this pixel (otherwise the convolution
will shift everything in the image).
OPTIONAL INPUT KEYWORDS:
FT_PSF = passes out/in the Fourier transform of the PSF,
(so that it can be re-used the next time function is called).
FT_IMAGE = passes out/in the Fourier transform of image.
/CORRELATE uses the conjugate of the Fourier transform of PSF,
to compute the cross-correlation of image and PSF,
(equivalent to IDL function convol() with NO rotation of PSF)
/AUTO_CORR computes the auto-correlation function of image using FFT.
/NO_FT overrides the use of FFT, using IDL function convol() instead.
(then PSF is rotated by 180 degrees to give same result)
/NO_PAD - if set, then do not pad the image to avoid edge effects.
This will improve memory and speed of the computation at the
expense of edge effects. This was the default method prior
to October 2009
METHOD:
When using FFT, PSF is centered & expanded to size of image.
HISTORY:
written, Frank Varosi, NASA/GSFC 1992.
Appropriate precision type for result depending on input image
Markus Hundertmark February 2006
Fix the bug causing the recomputation of FFT(psf) and/or FFT(image)
Sergey Koposov December 2006
Fix the centering bug
Kyle Penner October 2009
Add /No_PAD keyword for better speed and memory usage when edge effects
are not important. W. Landsman March 2010
Add warning when kernel type does not match integer array
W. Landsman Feb 2012
(See astrolib/pro/convolve.pro)
NAME:
COPY_STRUCT
PURPOSE:
Copy all fields with matching tag names from one structure to another
EXPLANATION:
COPY_STRUCT is similar to the intrinisc STRUCT_ASSIGN procedure but
has optional keywords to exclude or specify specific tags.
Fields with matching tag names are copied from one structure array to
another structure array of different type.
This allows copying of tag values when equating the structures of
different types is not allowed, or when not all tags are to be copied.
Can also recursively copy from/to structures nested within structures.
Note that the number of elements in the output structure array
is automatically adjusted to equal the length of input structure array.
If this not desired then use pro copy_struct_inx which allows
specifying via subscripts which elements are copied where in the arrays.
CALLING SEQUENCE:
copy_struct, struct_From, struct_To, NT_copied
copy_struct, struct_From, struct_To, EXCEPT=["image","misc"]
copy_struct, struct_From, struct_To, /RECUR_TANDEM
INPUTS:
struct_From = structure array to copy from.
struct_To = structure array to copy values to.
KEYWORDS:
EXCEPT_TAGS = string array of tag names to ignore (to NOT copy).
Used at all levels of recursion.
SELECT_TAGS = tag names to copy (takes priority over EXCEPT).
This keyword is not passed to recursive calls in order
to avoid the confusion of not copying tags in sub-structures.
/RECUR_FROM = search for sub-structures in struct_From, and then
call copy_struct recursively for those nested structures.
/RECUR_TO = search for sub-structures of struct_To, and then
call copy_struct recursively for those nested structures.
/RECUR_TANDEM = call copy_struct recursively for the sub-structures
with matching Tag names in struct_From and struct_To
(for use when Tag names match but sub-structure types differ).
OUTPUTS:
struct_To = structure array to which new tag values are copied.
NT_copied = incremented by total # of tags copied (optional)
INTERNAL:
Recur_Level = # of times copy_struct calls itself.
This argument is for internal recursive execution only.
The user call is 1, subsequent recursive calls increment it,
and the counter is decremented before returning.
The counter is used just to find out if argument checking
should be performed, and to set NT_copied = 0 first call.
EXTERNAL CALLS:
pro match (when keyword SELECT_TAGS is specified)
PROCEDURE:
Match Tag names and then use corresponding Tag numbers.
HISTORY:
written 1989 Frank Varosi STX @ NASA/GSFC
mod Jul.90 by F.V. added option to copy sub-structures RECURSIVELY.
mod Aug.90 by F.V. adjust # elements in TO (output) to equal
# elements in FROM (input) & count # of fields copied.
mod Jan.91 by F.V. added Recur_Level as internal argument so that
argument checking done just once, to avoid confusion.
Checked against Except_Tags in RECUR_FROM option.
mod Oct.91 by F.V. added option SELECT_TAGS= selected field names.
mod Aug.95 by W. Landsman to fix match of a single selected tag.
mod Mar.97 by F.V. do not pass the SELECT_TAGS keyword in recursion.
Converted to IDL V5.0 W. Landsman September 1997
mod May 01 by D. Schlegel use long integers
(See astrolib/pro/copy_struct.pro)
NAME:
COPY_STRUCT_INX
PURPOSE:
Copy matching tags & specified indices from one structure to another
EXPLANATION:
Copy all fields with matching tag names (except for "except_Tags")
from one structure array to another structure array of different type.
This allows copying of tag values when equating the structures of
different types is not allowed, or when not all tags are to be copied.
Can also recursively copy from/to structures nested within structures.
This procedure is same as copy_struct with option to
specify indices (subscripts) of which array elements to copy from/to.
CALLING SEQUENCE:
copy_struct_inx, struct_From, struct_To, NT_copied, INDEX_FROM=subf
copy_struct_inx, struct_From, struct_To, INDEX_FROM=subf, INDEX_TO=subto
INPUTS:
struct_From = structure array to copy from.
struct_To = structure array to copy values to.
KEYWORDS:
INDEX_FROM = indices (subscripts) of which elements of array to copy.
(default is all elements of input structure array)
INDEX_TO = indices (subscripts) of which elements to copy to.
(default is all elements of output structure array)
EXCEPT_TAGS = string array of Tag names to ignore (to NOT copy).
Used at all levels of recursion.
SELECT_TAGS = Tag names to copy (takes priority over EXCEPT).
This keyword is not passed to recursive calls in order
to avoid the confusion of not copying tags in sub-structures.
/RECUR_FROM = search for sub-structures in struct_From, and then
call copy_struct recursively for those nested structures.
/RECUR_TO = search for sub-structures of struct_To, and then
call copy_struct recursively for those nested structures.
/RECUR_TANDEM = call copy_struct recursively for the sub-structures
with matching Tag names in struct_From and struct_To
(for use when Tag names match but sub-structure types differ).
OUTPUTS:
struct_To = structure array to which new tag values are copied.
NT_copied = incremented by total # of tags copied (optional)
INTERNAL:
Recur_Level = # of times copy_struct_inx calls itself.
This argument is for internal recursive execution only.
The user call is 1, subsequent recursive calls increment it,
and the counter is decremented before returning.
The counter is used just to find out if argument checking
should be performed, and to set NT_copied = 0 first call.
EXTERNAL CALLS:
pro match (when keyword SELECT_TAGS is specified)
PROCEDURE:
Match Tag names and then use corresponding Tag numbers,
apply the sub-indices during = and recursion.
HISTORY:
adapted from copy_struct: 1991 Frank Varosi STX @ NASA/GSFC
mod Aug.95 by F.V. to fix match of a single selected tag.
mod Mar.97 by F.V. do not pass the SELECT_TAGS keyword in recursion,
and check validity of INDEX_FROM and INDEX_TO in more detail.
Converted to IDL V5.0 W. Landsman September 1997
Use long integers W. Landsman May 2001
(See astrolib/pro/copy_struct_inx.pro)
NAME:
CORREL_IMAGES
PURPOSE:
Compute the 2-D cross-correlation function of two images
EXPLANATION:
Computes the 2-D cross-correlation function of two images for
a range of (x,y) shifting by pixels of one image relative to the other.
CALLING SEQUENCE:
Result = CORREL_IMAGES( image_A, image_B,
[XSHIFT=, YSHIFT=, XOFFSET_B=, YOFFSET_B=, REDUCTION=,
MAGNIFICATION=, /NUMPIX, /MONITOR )
INPUTS:
image_A, image_B = the two images of interest.
OPTIONAL INPUT KEYWORDS:
XSHIFT = the + & - shift to be applied in X direction, default=7.
YSHIFT = the Y direction + & - shifting, default=7.
XOFFSET_B = initial X pixel offset of image_B relative to image_A.
YOFFSET_B = Y pixel offset, defaults are (0,0).
REDUCTION = optional reduction factor causes computation of
Low resolution correlation of bin averaged images,
thus faster. Can be used to get approximate optimal
(x,y) offset of images, and then called for successive
lower reductions in conjunction with CorrMat_Analyze
until REDUCTION=1, getting offset up to single pixel.
MAGNIFICATION = option causes computation of high resolution correlation
of magnified images, thus much slower.
Shifting distance is automatically = 2 + Magnification,
and optimal pixel offset should be known and specified.
Optimal offset can then be found to fractional pixels
using CorrMat_Analyze( correl_images( ) ).
/NUMPIX - if set, causes the number of pixels for each correlation
to be saved in a second image, concatenated to the
correlation image, so Result is fltarr( Nx, Ny, 2 ).
/MONITOR causes the progress of computation to be briefly printed.
OUTPUTS:
Result is the cross-correlation function, given as a matrix.
PROCEDURE:
Loop over all possible (x,y) shifts, compute overlap and correlation
for each shift. Correlation set to zero when there is no overlap.
MODIFICATION HISTORY:
Written, July,1991, Frank Varosi, STX @ NASA/GSFC
Use ROUND instead of NINT, June 1995, Wayne Landsman HSTX
Avoid divide by zero errors, W. Landsman HSTX April 1996
Remove use of !DEBUG W. Landsman June 1997
Subtract mean of entire image before computing correlation, not just
mean of overlap region H. Ebeling/W. Landsman June 1998
Always REBIN() using floating pt arithmetic W. Landsman Nov 2007
(See astrolib/pro/correl_images.pro)
NAME: CORREL_OPTIMIZE PURPOSE: Find the optimal (x,y) pixel offset of image_B relative to image_A EXPLANATION" Optimal offset is computed by means of maximizing the correlation function of the two images. CALLING SEQUENCE: CORREL_OPTIMIZE, image_A, image_B, xoffset_optimum, yoffset_optimum [ XOFF_INIT=, YOFF_INIT=, MAGNIFICATION=, /PRINT, /NUMPIX, /MONITOR, PLATEAU_THRESH= ] INPUTS: image_A, image_B = the two images of interest. OPTIONAL INPUT KEYWORDS: XOFF_INIT = initial X pixel offset of image_B relative to image_A, YOFF_INIT = Y pixel offset, (default offsets are 0 and 0). MAGNIFICATION = option to determine offsets up to fractional pixels, (example: MAG=2 means 1/2 pixel accuracy, default=1). /NUMPIX: sqrt( sqrt( # pixels )) used as correlation weighting factor. /MONITOR causes the progress of computation to be briefly printed. /PRINT causes the results of analysis to be printed. PLATEAU_THRESH = threshold used for detecting plateaus in the cross-correlation matrix near maximum, (default=0.01), used only if MAGNIFICATION > 1. Decrease this value for high signal-to-noise data OUTPUTS: xoffset_optimum = optimal X pixel offset of image_B relative to image_A. yoffset_optimum = optimal Y pixel offset. CALLS: function correl_images( image_A, image_B ) pro corrmat_analyze PROCEDURE: The combination of function correl_images( image_A, image_B ) and corrmat_analyze of the result is used to obtain the (x,y) offset yielding maximal correlation. The combination is first executed at large REDUCTION factors to speed up computation, then zooming in recursively on the optimal (x,y) offset by factors of 2. Finally, the MAGNIFICATION option (if specified) is executed to determine the (x,y) offset up to fractional pixels. MODIFICATION HISTORY: Written, July,1991, Frank Varosi, STX @ NASA/GSFC Added PLATEAU_THRESH keyword June 1997, Wayne Landsman STX Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/correl_optimize.pro)
NAME: CORRMAT_ANALYZE PURPOSE: Find the optimal (x,y) offset to maximize correlation of 2 images EXPLANATION: Analyzes the 2-D cross-correlation function of two images and finds the optimal(x,y) pixel offsets. Intended for use with function CORREL_IMAGES. CALLING SEQUENCE: corrmat_analyze, correl_mat, xoffset_optimum, yoffset_optimum, max_corr, edge, plateau, [XOFF_INIT=, YOFF_INIT=, REDUCTION=, MAGNIFICATION=, PLATEAU_THRESH=, /PRINT] INPUTS: correl_mat = the cross-correlation matrix of 2 images. (as computed by function CORREL_IMAGES( imA, imB ) ). NOTE: If correl_mat(*,*,1) is the number of pixels for each correlation, (the case when /NUMPIX was specified in call to CORREL_IMAGES) then sqrt( sqrt( # pixels )) is used as correlation weighting factor. OPTIONAL INPUT KEYWORDS: XOFF_INIT = initial X pixel offset of image_B relative to image_A. YOFF_INIT = Y pixel offset, (both as specified to correl_images). REDUCTION = reduction factor used in call to CORREL_IMAGES. MAGNIFICATION = magnification factor used in call to CORREL_IMAGES, this allows determination of offsets up to fractions of a pixel. PLATEAU_THRESH = threshold used for detecting plateaus in the cross-correlation matrix near maximum, (default=0.01), used only if MAGNIFICATION > 1 /PRINT causes the result of analysis to be printed. OUTPUTS: xoffset_optimum = optimal X pixel offset of image_B relative to image_A. yoffset_optimum = optimal Y pixel offset. max_corr = the maximal correlation corresponding to optimal offset. edge = 1 if maximum is at edge of correlation domain, otherwise=0. plateau = 1 if maximum is in a plateua of correlation function, else=0. PROCEDURE: Find point of maximum cross-correlation and calc. corresponding offsets. If MAGNIFICATION > 1: the correl_mat is checked for plateau near maximum, and if found, the center of plateau is taken as point of maximum cross-correlation. MODIFICATION HISTORY: Written, July-1991, Frank Varosi, STX @ NASA/GSFC Use ROUND instead of NINT, June 1995 Wayne Landsman HSTX Remove use of non-standard !DEBUG system variable W.L. HSTX Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/corrmat_analyze.pro)
NAME:
COSMO_PARAM
PURPOSE:
Derive full set of cosmological density parameters from a partial set
EXPLANATION:
This procedure is called by LUMDIST and GALAGE to allow the user a choice
in defining any two of four cosmological density parameters.
Given any two of the four input parameters -- (1) the normalized matter
density Omega_m (2) the normalized cosmological constant, Omega_lambda
(3) the normalized curvature term, Omega_k and (4) the deceleration
parameter q0 -- this program will derive the remaining two. Here
"normalized" means divided by the closure density so that
Omega_m + Omega_lambda + Omega_k = 1. For a more
precise definition see Carroll, Press, & Turner (1992, ArAA, 30, 499).
If less than two parameters are defined, this procedure sets default
values of Omega_k=0 (flat space), Omega_lambda = 0.7, Omega_m = 0.3
and q0 = -0.55
CALLING SEQUENCE:
COSMO_PARAM, Omega_m, Omega_lambda, Omega_k, q0
INPUT-OUTPUTS:
Omega_M - normalized matter energy density, non-negative numeric scalar
Omega_Lambda - Normalized cosmological constant, numeric scalar
Omega_k - normalized curvature parameter, numeric scalar. This is zero
for a flat universe
q0 - Deceleration parameter, numeric scalar = -R*(R'')/(R')^2
= 0.5*Omega_m - Omega_lambda
NOTES:
If more than two parameters are defined upon input (overspecification),
then the first two defined parameters in the ordered list Omega_m,
Omega_lambda, Omega_k, q0 are used to define the cosmology.
EXAMPLE:
Suppose one has Omega_m = 0.3, and Omega_k = 0.5 then to determine
Omega_lambda and q0
IDL> cosmo_param, 0.3, omega_lambda, 0.5, q0
which will return omega_lambda = 0.2 and q0 = -2.45
REVISION HISTORY:
W. Landsman Raytheon ITSS April 2000
Better Error checking W. Landsman/D. Syphers October 2010
(See astrolib/pro/cosmo_param.pro)
NAME:
CO_ABERRATION
PURPOSE:
Calculate changes to Ra and Dec due to the effect of annual aberration
EXPLANATION:
as described in Meeus, Chap 23.
CALLING SEQUENCE:
co_aberration, jd, ra, dec, d_ra, d_dec, [EPS = ]
INPUTS
jd : Julian Date [scalar or vector]
ra, dec : Arrays (or scalars) of the ra and dec's in degrees
Note: if jd is a vector, then ra and dec must either be scalars, or
vectors of the same length.
OUTPUTS
d_ra, d_dec: the corrections to ra and dec due to aberration in
arcseconds. (These values can be added to the true RA
and dec to get the apparent position). Note that d_ra
is *not* multiplied by cos(dec), so that
apparent_ra = ra + d_ra/3600.
OPTIONAL INPUT KEYWORD:
eps : set this to the true obliquity of the ecliptic (in radians), or
it will be set for you if you don't know it (in that case, set it to
an empty variable).
EXAMPLE:
Compute the change in RA and Dec of Theta Persei (RA = 2h46m,11.331s, Dec =
49d20',54.54") due to aberration on 2028 Nov 13.19 TD
IDL> jdcnv,2028,11,13,.19*24,jd ;Get Julian date
IDL> co_aberration,jd,ten(2,46,11.331)*15,ten(49,20,54.54),d_ra,d_dec
==> d_ra = 30.045" (=2.003s) d_dec = 6.697"
NOTES:
These formula are from Meeus, Chapters 23. Accuracy is much better than 1
arcsecond.
The maximum deviation due to annual aberration is 20.49" and occurs when the
Earth velocity is perpendicular to the direction of the star.
REVISION HISTORY:
Written, June 2002, Chris O'Dell, U. of Wisconsin
Fix error with vector input W. Landsman June 2009
June 2009 update fixed case where JD was scalar but RA,Dec were vectors, but
broke the case when both JD and RA,Dec were vectors Aug 2012 W. Landsman
(See astrolib/pro/co_aberration.pro)
NAME:
CO_NUTATE
PURPOSE:
Calculate changes in RA and Dec due to nutation of the Earth's rotation
EXPLANATION:
Calculates necessary changes to ra and dec due to
the nutation of the Earth's rotation axis, as described in Meeus, Chap 23.
Uses formulae from Astronomical Almanac, 1984, and does the calculations
in equatorial rectangular coordinates to avoid singularities at the
celestial poles.
CALLING SEQUENCE:
CO_NUTATE, jd, ra, dec, d_ra, d_dec, [EPS=, D_PSI =, D_EPS = ]
INPUTS
JD: Julian Date [scalar or vector]
RA, DEC : Arrays (or scalars) of the ra and dec's of interest
Note: if jd is a vector, ra and dec MUST be vectors of the same length.
OUTPUTS:
d_ra, d_dec: the corrections to ra and dec due to nutation (must then
be added to ra and dec to get corrected values).
OPTIONAL OUTPUT KEYWORDS:
EPS: set this to a named variable that will contain the obliquity of the
ecliptic.
D_PSI: set this to a named variable that will contain the nutation in the
longitude of the ecliptic
D_EPS: set this to a named variable that will contain the nutation in the
obliquity of the ecliptic
EXAMPLE:
(1) Example 23a in Meeus: On 2028 Nov 13.19 TD the mean position of Theta
Persei is 2h 46m 11.331s 49d 20' 54.54". Determine the shift in
position due to the Earth's nutation.
IDL> jd = JULDAY(11,13,2028,.19*24) ;Get Julian date
IDL> CO_NUTATE, jd,ten(2,46,11.331)*15.,ten(49,20,54.54),d_ra,d_dec
====> d_ra = 15.843" d_dec = 6.217"
PROCEDURES USED:
NUTATE
REVISION HISTORY:
Written Chris O'Dell, 2002
Vector call to NUTATE W. Landsman June 2002
(See astrolib/pro/co_nutate.pro)
NAME:
CO_REFRACT()
PURPOSE:
Calculate correction to altitude due to atmospheric refraction.
DESCRIPTION:
CO_REFRACT can calculate both apparent altitude from observed altitude and
vice-versa.
CALLING SEQUENCE:
new_alt = CO_REFRACT(old_alt, [ ALTITUDE= , PRESSURE= , $
TEMPERATURE= , /TO_OBSERVED , EPSILON= ])
INPUT:
old_alt - Observed (apparent) altitude, in DEGREES. (apparent if keyword
/TO_OBSERVED set). May be scalar or vector.
OUTPUT:
Function returns apparent (observed) altitude, in DEGREES. (observed if
keyword /TO_OBSERVED set). Will be of same type as input
altitude(s).
OPTIONAL KEYWORD INPUTS:
ALTITUDE : The height of the observing location, in meters. This is
only used to determine an approximate temperature and pressure,
if these are not specified separately. [default=0, i.e. sea level]
PRESSURE : The pressure at the observing location, in millibars.
TEMPERATURE: The temperature at the observing location, in Kelvin.
EPSILON: When keyword /TO_OBSERVED has been set, this is the accuracy
to obtain via the iteration, in arcseconds [default = 0.25
arcseconds].
/TO_OBSERVED: Set this keyword to go from Apparent->Observed altitude,
using the iterative technique.
Note, if altitude is set, but temperature or pressure are not, the
program will make an intelligent guess for the temperature and pressure.
DESCRIPTION:
Because the index of refraction of air is not precisely 1.0, the atmosphere
bends all incoming light, making a star or other celestial object appear at
a slightly different altitude (or elevation) than it really is. It is
important to understand the following definitions:
Observed Altitude: The altitude that a star is SEEN to BE, with a telescope.
This is where it appears in the sky. This is always
GREATER than the apparent altitude.
Apparent Altitude: The altitude that a star would be at, if *there were no
atmosphere* (sometimes called "true" altitude). This is
usually calculated from an object's celestial coordinates.
Apparent altitude is always LOWER than the observed
altitude.
Thus, for example, the Sun's apparent altitude when you see it right on the
horizon is actually -34 arcminutes.
This program uses couple simple formulae to estimate the effect for most
optical and radio wavelengths. Typically, you know your observed altitude
(from an observation), and want the apparent altitude. To go the other way,
this program uses an iterative approach.
EXAMPLE:
The lower limb of the Sun is observed to have altitude of 0d 30'.
Calculate the the true (=apparent) altitude of the Sun's lower limb using
mean conditions of air pressure and temperature
IDL> print, co_refract(0.5) ===> 0.025degrees (1.55')
WAVELENGTH DEPENDENCE:
This correction is 0 at zenith, about 1 arcminute at 45 degrees, and 34
arcminutes at the horizon FOR OPTICAL WAVELENGTHS. The correction is
NON-NEGLIGIBLE at all wavelengths, but is not very easily calculable.
These formulae assume a wavelength of 550 nm, and will be accurate to
about 4 arcseconds for all visible wavelengths, for elevations of 10
degrees and higher. Amazingly, they are also ACCURATE FOR RADIO
FREQUENCIES LESS THAN ~ 100 GHz.
It is important to understand that these formulae really can't do better
than about 30 arcseconds of accuracy very close to the horizon, as
variable atmospheric effects become very important.
REFERENCES:
1. Meeus, Astronomical Algorithms, Chapter 15.
2. Explanatory Supplement to the Astronomical Almanac, 1992.
3. Methods of Experimental Physics, Vol 12 Part B, Astrophysics,
Radio Telescopes, Chapter 2.5, "Refraction Effects in the Neutral
Atmosphere", by R.K. Crane.
DEPENDENCIES:
CO_REFRACT_FORWARD (contained in this file and automatically compiled).
AUTHOR:
Chris O'Dell
Univ. of Wisconsin-Madison
Observational Cosmology Laboratory
Email: [email protected]
REVISION HISTORY:
version 1 (May 31, 2002)
Update iteration formula, W. Landsman June 2002
Corrected slight bug associated with scalar vs. vector temperature and
pressure inputs. 6/10/2002
Fixed problem with vector input when /TO_OBSERVED set W. Landsman Dec 2005
Allow arrays with more than 32767 elements W.Landsman/C.Dickinson Feb 2010
(See astrolib/pro/co_refract.pro)
NAME:
CREATE_STRUCT
PURPOSE:
Create an IDL structure from a list of tag names and dimensions
EXPLANATION:
Dynamically create an IDL structure variable from list of tag names
and data types of arbitrary dimensions. Useful when the type of
structure needed is not known until run time.
Unlike the intrinsic function CREATE_STRUCT(), this procedure does not
require the user to know the number of tags before run time. (Note
there is no name conflict since the intrinsic CREATE_STRUCT is a
function, and this file contains a procedure.)
CALLING SEQUENCE:
CREATE_STRUCT, STRUCT, strname, tagnames, tag_descript,
[ DIMEN = , /CHATTER, /NODELETE ]
INPUTS:
STRNAME - name to be associated with structure (string)
Must be unique for each structure created. Set
STRNAME = '' to create an anonymous structure
TAGNAMES - tag names for structure elements (string or string array)
Any strings that are not valid IDL tag names (e.g. 'a\2')
will be converted by IDL_VALIDNAME to a valid tagname by
replacing with underscores as necessary (e.g. 'a_2')
TAG_DESCRIPT - String descriptor for the structure, containing the
tag type and dimensions. For example, 'A(2),F(3),I', would
be the descriptor for a structure with 3 tags, strarr(2),
fltarr(3) and Integer scalar, respectively.
Allowed types are 'A' for strings, 'B' or 'L' for unsigned byte
integers, 'I' for integers, 'J' for longword integers,
'K' for 64bit integers, 'F' or 'E' for floating point,
'D' for double precision 'C' for complex, and 'M' for double
complex. Uninterpretable characters in a format field are
ignored.
For vectors, the tag description can also be specified by
a repeat count. For example, '16E,2J' would specify a
structure with two tags, fltarr(16), and lonarr(2)
OPTIONAL KEYWORD INPUTS:
DIMEN - number of dimensions of structure array (default is 1)
CHATTER - If set, then CREATE_STRUCT() will display
the dimensions of the structure to be created, and prompt
the user whether to continue. Default is no prompt.
/NODELETE - If set, then the temporary file created
CREATE_STRUCT will not be deleted upon exiting. See below
OUTPUTS:
STRUCT - IDL structure, created according to specifications
EXAMPLES:
IDL> create_struct, new, 'name',['tag1','tag2','tag3'], 'D(2),F,A(1)'
will create a structure variable new, with structure name NAME
To see the structure of new:
IDL> help,new,/struc
** Structure NAME, 3 tags, 20 length:
TAG1 DOUBLE Array(2)
TAG2 FLOAT 0.0
TAG3 STRING Array(1)
PROCEDURE:
Generates a temporary procedure file using input information with
the desired structure data types and dimensions hard-coded.
This file is then executed with CALL_PROCEDURE.
NOTES:
If CREATE_STRUCT cannot write a temporary .pro file in the current
directory, then it will write the temporary file in the getenv('HOME')
directory.
Note that 'L' now specifies a LOGICAL (byte) data type and not a
a LONG data type for consistency with FITS binary tables
RESTRICTIONS:
The name of the structure must be unique, for each structure created.
Otherwise, the new variable will have the same structure as the
previous definition (because the temporary procedure will not be
recompiled). ** No error message will be generated ***
SUBROUTINES CALLED:
REPCHR()
MODIFICATION HISTORY:
Version 1.0 RAS January 1992
Modified 26 Feb 1992 for Rosat IDL Library (GAR)
Modified Jun 1992 to accept arrays for tag elements -- KLV, Hughes STX
Accept anonymous structures W. Landsman HSTX Sep. 92
Accept 'E' and 'J' format specifications W. Landsman Jan 93
'L' format now stands for logical and not long array
Accept repeat format for vectors W. Landsman Feb 93
Accept complex and double complex (for V4.0) W. Landsman Jul 95
Work for long structure definitions W. Landsman Aug 97
Write temporary file in HOME directory if necessary W. Landsman Jul 98
Use OPENR,/DELETE for OS-independent file removal W. Landsman Jan 99
Use STRSPLIT() instead of GETTOK() W. Landsman July 2002
Assume since V5.3 W. Landsman Feb 2004
Added RESOLVE_ROUTINE to ensure recompilation W. Landsman Sep. 2004
Delete temporary with FILE_DELETE W. Landsman Sep 2006
Assume since V5.5, delete VMS reference W.Landsman Sep 2006
Added 'K' format for 64 bit integers, IDL_VALIDNAME check on tags
W. Landsman Feb 2007
Use vector form of IDL_VALIDNAME() if V6.4 or later W.L. Dec 2007
Suppress compilation mesage of temporary file A. Conley/W.L. May 2009
Remove FDECOMP, some cleaner coding W.L. July 2009
Do not limit string length to 1000 chars P. Broos, Feb 2011
(See astrolib/pro/create_struct.pro)
NAME:
CR_REJECT
PURPOSE:
General, iterative cosmic ray rejection using two or more input images.
EXPLANATION:
Uses a noise model input by the user, rather than
determining noise empirically from the images themselves.
The image returned has the combined exposure time of all the input
images, unless the bias flag is set, in which case the mean is
returned. This image is computed by summation (or taking mean)
regardless of loop and initialization options (see below).
CALLING SEQUENCE:
cr_reject, input_cube, rd_noise_dn, dark_dn, gain, mult_noise, $
combined_image, combined_npix, combined_noise
MODIFIED ARGUMENT:
input_cube - Cube in which each plane is an input image.
If the noise model is used (rd_noise_dn, dark_dn,
gain), then input_cube must be in units of DN.
If an input noise cube is supplied (rd_noise_dn
<0), then the units of input_cube and noise_cube
merely need to be consistent.
This array is used as a buffer and its contents
are not guaranteed on output (although for now,
weighting=0 with /restore_sky should give you back
your input unaltered).
INPUT ARGUMENTS:
rd_noise_dn - Read noise per pixel. Units are DN.
If negative, then the user supplies an error cube
via the keyword noise_cube. In the latter case,
mult_noise still applies, since it is basically a fudge.
dark_dn - Dark rate in DN per pixel per s. This can be a scalar,
or it can be a dark image divided by the exposure
time.
gain - Electrons per DN.
mult_noise - Coefficient for multiplicative noise term -- helps
account for differing PSFs or subpixel image shifts.
INPUT KEYWORDS:
exptime - If the images have different exposure times, pass
them in a vector. You can leave this off for
frames with the same exposure time, but dark counts
won't be treated correctly.
verbose - If set, lots of output.
nsig - Rejection limit in units of pixel-to-pixel noise
(sigma) on each input image. Can be specified as
an array, in which case the dimension gives the
maximum number of iterations to run. (Default =
[8, 6, 4]
dilation - With dfactor, provides functionality similar to the
expansion of the CR with pfactor and radius in STSDAS
crrej. Dilate gives the size of the border to be
tested around each initially detected CR pixel.
E.g., dilate=1 searches a 9 X 9 area centered on the
original pixel. If dfactor is set, the default is 1.
dfactor - See dilation. This parameter is equivalent to pfactor
in STSDAS crrej. The current threshold for rejection
is multiplied by this factor when doing the search
with the dilated mask. If dilation is set, the default
for this parameter is 0.5.
bias - Set if combining biases (divides through by number
of images at end, since exposure time is 0).
tracking_set - Subscripts of pixels to be followed through the
computation.
noskyadjust - Sky not to be subtracted before rejection tests. Default
is to do the subtraction.
xmedsky - Flag. If set, the sky is computed as a 1-d array
which is a column-by-column median. This is intended
for STIS slitless spectra. If sky adjustment is
disabled, this keyword has no effect.
input_mask - Mask cube input by the user. Should be byte data
because it's boolean. 1 means use the pixel,
and 0 means reject the pixel - these rejections
are in addition to those done by the CR rejection
algorithm as such.
The following keywords control how the current guess at a CR-free
"check image" is recomputed on each iteration:
median_loop - If set, the check image for each iteration is
the pixel-by-pixel median. THE MEAN IS
RETURNED in combined_image even if you set
this option. (Default is mean_loop.)
minimum_loop - If set, the check image for each iteration is
the pixel-by-pixel minimum. THE MEAN IS
RETURNED in combined_image even if you set
this option. (Default is mean_loop.)
mean_loop - If set, the check image for each iteration is
the pixel-by-pixel mean. (Same as the default.)
noclearmask - By default, the mask of CR flags is reset before
every iteration, and a pixel that has been
rejected has a chance to get back in the game
if the average migrates toward its value. If this
keyword is set, then any rejected pixel stays
rejected in subsequent iterations. Note that what
stsdas.hst_calib.wfpc.crrej does is the same
as the default. For this procedure, the default
was NOT to clear the flags, until 20 Oct. 1997.
restore_sky - Flag. If set, the routine adds the sky back into
input_cube before returning. Works only if
weighting=0.
null_value - Value to be used for output pixels to which no
input pixels contribute. Default=0
weighting - Selects weighting scheme in final image
combination:
0 (default) - Poissonian weighting - co-add
detected DN from non-CR pixels. (Pixel-by-
pixel scaling up to total exposure time,
for pixels in stack where some rejected.)
Equivalent to exptime weighting of rates.
1 or more - Sky and read noise weighting of rates.
Computed as weighted average of DN rates,
with total exp time multiplied back in
afterward.
In all cases, the image is returned as a sum in
DN with the total exposure time of the image
stack, and with total sky added back in.
The following keywords allow the initial guess at a CR-free "check
image" to be of a different kind from the iterative guesses:
init_med - If set, the initial check image is
the pixel-by-pixel median. (Not permitted if
input_cube has fewer than 3 planes; default is minimum.)
init_mean - If set, the initial check image is
the pixel-by-pixel mean. (Default is minimum.)
init_min - If set, the initial check image is
the pixel-by-pixel minimum. (Same as the default.)
OUTPUT ARGUMENTS::
combined_image - Mean image with CRs removed.
combined_npix - Byte (or integer) image of same dimensions as
combined_image, with each element containing
the number of non-CR stacked pixels that
went into the result.
combined_noise - Noise in combined image according to noise model
or supplied noise cube.
OUTPUT KEYWORDS:
mask_cube - CR masks for each input image. 1 means
good pixel; 0 means CR pixel.
skyvals - Sky value array. For an image cube with N planes,
this array is fltarr(N) if the sky is a scalar per
image plane, and fltarr(XDIM, N), is the XMEDSKY
is set.
INPUT/OUTPUT KEYWORD:
noise_cube - Estimated noise in each pixel of input_cube as
returned (if rd_noise_dn ge 0), or input noise
per pixel of image_cube (if rd_noise_dn lt 0).
skybox - X0, X1, Y0, Y1 bounds of image section used
to compute sky. If supplied by user, this
region is used. If not supplied, the
image bounds are returned. This parameter might
be used (for instance) if the imaging area
doesn't include the whole chip.
COMMON BLOCKS: none
SIDE EFFECTS: none
METHOD:
COMPARISON WITH STSDAS
Cr_reject emulates the crrej routine in stsdas.hst_calib.wfpc.
The two routines have been verified to give identical results
(except for some pixels along the edge of the image) under the
following conditions:
no sky adjustment
no dilation of CRs
initialization of trial image with minimum
taking mean for each trial image after first (no choice
in crrej)
Dilation introduces a difference between crrej and this routine
around the very edge of the image, because the IDL mask
manipulation routines don't handle the edge the same way as crrej
does. Away from the edge, crrej and cr_reject are the same with
respect to dilation.
The main difference between crrej and cr_reject is in the sky
computation. Cr_reject does a DAOPHOT I sky computation on a
subset of pixels grabbed from the image, whereas crrej searches
for a histogram mode.
REMARKS ON USAGE
The default is that the initial guess at a CR-free image is the
pixel-by-pixel minimum of all the input images. The pixels
cut from each component image are the ones more than nsig(0) sigma
from this minimum image. The next iteration is based on the
mean of the cleaned-up component images, and the cut is taken
at nsig(1) sigma. The next iteration is also based on the mean with
the cut taken at nsig(2) sigma.
The user can specify an arbitrary sequence of sigma cuts, e.g.,
nsig=[6,2] or nsig=[10,9,8,7]. The user can also specify that
the initial guess is the median (/init_med) rather than the
minimum, or even the mean. The iterated cleaned_up images after
the first guess can be computed as the mean or the median
(/mean_loop or /median_loop). The minimum_loop option is also
specified, but this is a trivial case, and you wouldn't want
to use it except perhaps for testing.
The routine takes into account exposure time if you want it to,
i.e., if the pieces of the CR-split aren't exactly the same.
For bias frames (exposure time 0), set /bias to return the mean
rather than the total of the cleaned-up component images.
The crrej pfactor and radius to propagate the detected CRs
outward from their initial locations have been implemented
in slightly different form using the IDL DILATE function.
It is possible to end up with output pixels to which no valid
input pixels contribute. These end up with the value
NULL_VALUE, and the corresponding pixels of combined_npix are
also returned as 0. This result can occur when the pixel is
very noisy across the whole image stack, i.e., if all the
values are, at any step of the process, far from the stack
average at that position even after rejecting the real
outliers. Because pixels are flagged symmetrically N sigma
above and below the current combined image (see code), all
the pixels at a given position can end up getting flagged.
(At least, that's how I think it happens.)
MODIFICATION HISTORY:
5 Mar. 1997 - Written. R. S. Hill
14 Mar. 1997 - Changed to masking approach to keep better
statistics and return CR-affected pixels to user.
Option to track subset of pixels added.
Dilation of initially detected CRs added.
Other small changes. RSH
17 Mar. 1997 - Arglist and treatment of exposure times fiddled
to mesh better with stis_cr. RSH
25 Mar. 1997 - Fixed bug if dilation finds nothing. RSH
4 Apr. 1997 - Changed name to cr_reject. RSH
15 Apr. 1997 - Restyled with emacs, nothing else done. RSH
18 Jun. 1997 - Input noise cube allowed. RSH
19 Jun. 1997 - Multiplicative noise deleted from final error. RSH
20 Jun. 1997 - Fixed error in using input noise cube. RSH
12 July 1997 - Sky adjustment option. RSH
27 Aug. 1997 - Dilation kernel made round, not square, and
floating-point radius allowed. RSH
16 Sep. 1997 - Clearmask added. Intermediate as well as final
mean is exptime weighted. RSH
17 Sep. 1997 - Redundant zeroes around dilation kernel trimmed. RSH
1 Oct. 1997 - Bugfix in preceding. RSH
21 Oct. 1997 - Clearmask changed to noclearmask. Bug in robust
array division fixed (misplaced parens). Sky as
a function of X (option). RSH
30 Jan. 1998 - Restore_sky keyword added. RSH
5 Feb. 1998 - Quick help corrected and updated. RSH
6 Feb. 1998 - Fixed bug in execution sequence for tracking_set
option. RSH
18 Mar. 1998 - Eliminated confusing maxiter spec. Added
null_value keyword. RSH
15 May 1998 - Input_mask keyword. RSH
27 May 1998 - Initialization of minimum image corrected. NRC, RSH
9 June 1998 - Input mask cube processing corrected. RSH
21 Sep. 1998 - Weighting keyword added. RSH
7 Oct. 1998 - Fixed bug in input_mask processing (introduced
in preceding update). Input_mask passed to
skyadj_cube. RSH
5 Mar. 1999 - Force init_min for 2 planes. RSH
1 Oct. 1999 - Make sure weighting=1 not given with noise cube. RSH
1 Dec. 1999 - Corrections to doc; restore_sky needs weighting=0. RSH
17 Mar. 2000 - SKYBOX added. RSH
(See astrolib/pro/cr_reject.pro)
NAME:
CSPLINE
PURPOSE:
Function to evaluate a natural cubic spline at specified data points
EXPLANATION:
Combines the Numerical Recipes functions SPL_INIT and SPL_INTERP
CALLING SEQUENCE:
result = cspline( x, y, t, [ DERIV = ])
INPUTS:
x - vector of spline node positions, must be monotonic increasing or
decreasing
y - vector of node values
t - x-positions at which to evaluate the spline, scalar or vector
INPUT-OUTPUT KEYWORD:
DERIV - values of the second derivatives of the interpolating function
at the node points. This is an intermediate step in the
computation of the natural spline that requires only the X and
Y vectors. If repeated interpolation is to be applied to
the same (X,Y) pair, then some computation time can be saved
by supplying the DERIV keyword on each call. On the first call
DERIV will be computed and returned on output.
OUTPUT:
the values for positions t are returned as the function value
If any of the input variables are double precision, then the output will
also be double precision; otherwise the output is floating point.
EXAMPLE:
The following uses the example vectors from the SPL_INTERP documentation
IDL> x = (findgen(21)/20.0)*2.0*!PI ;X vector
IDL> y = sin(x) ;Y vector
IDL> t = (findgen(11)/11.0)*!PI ;Values at which to interpolate
IDL> cgplot,x,y,psym=1 ;Plot original grid
IDL> cgplot, /over, t,cspline(x,y,t),psym=2 ;Overplot interpolated values
METHOD:
The "Numerical Recipes" implementation of the natural cubic spline is
used, by calling the intrinsic IDL functions SPL_INIT and SPL_INTERP.
HISTORY:
version 1 D. Lindler May, 1989
version 2 W. Landsman April, 1997
Rewrite using the intrinsic SPL_INIT & SPL_INTERP functions
Converted to IDL V5.0 W. Landsman September 1997
Work for monotonic decreasing X vector W. Landsman February 1999
(See astrolib/pro/cspline.pro)
NAME:
CT2LST
PURPOSE:
To convert from Local Civil Time to Local Mean Sidereal Time.
CALLING SEQUENCE:
CT2LST, Lst, Lng, Tz, Time, [Day, Mon, Year]
or
CT2LST, Lst, Lng, dummy, JD
INPUTS:
Lng - The longitude in degrees (east of Greenwich) of the place for
which the local sidereal time is desired, scalar. The Greenwich
mean sidereal time (GMST) can be found by setting Lng = 0.
Tz - The time zone of the site in hours, positive East of the Greenwich
meridian (ahead of GMT). Use this parameter to easily account
for Daylight Savings time (e.g. -4=EDT, -5 = EST/CDT), scalar
This parameter is not needed (and ignored) if Julian date is
supplied. ***Note that the sign of TZ was changed in July 2008
to match the standard definition.***
Time or JD - If more than four parameters are specified, then this is
the time of day of the specified date in decimal hours. If
exactly four parameters are specified, then this is the
Julian date of time in question, scalar or vector
OPTIONAL INPUTS:
Day - The day of the month (1-31),integer scalar or vector
Mon - The month, in numerical format (1-12), integer scalar or vector
Year - The 4 digit year (e.g. 2008), integer scalar or vector
OUTPUTS:
Lst The Local Sidereal Time for the date/time specified in hours.
RESTRICTIONS:
If specified, the date should be in numerical form. The year should
appear as yyyy.
PROCEDURE:
The Julian date of the day and time is question is used to determine
the number of days to have passed since 0 Jan 2000. This is used
in conjunction with the GST of that date to extrapolate to the current
GST; this is then used to get the LST. See Astronomical Algorithms
by Jean Meeus, p. 84 (Eq. 11-4) for the constants used.
EXAMPLE:
Find the Greenwich mean sidereal time (GMST) on 2008 Jul 30 at 15:53 pm
in Baltimore, Maryland (longitude=-76.72 degrees). The timezone is
EDT or tz=-4
IDL> CT2LST, lst, -76.72, -4,ten(15,53), 30, 07, 2008
==> lst = 11.356505 hours (= 11h 21m 23.418s)
The Web site http://tycho.usno.navy.mil/sidereal.html contains more
info on sidereal time, as well as an interactive calculator.
PROCEDURES USED:
jdcnv - Convert from year, month, day, hour to julian date
MODIFICATION HISTORY:
Adapted from the FORTRAN program GETSD by Michael R. Greason, STX,
27 October 1988.
Use IAU 1984 constants Wayne Landsman, HSTX, April 1995, results
differ by about 0.1 seconds
Longitudes measured *east* of Greenwich W. Landsman December 1998
Time zone now measure positive East of Greenwich W. Landsman July 2008
Remove debugging print statement W. Landsman April 2009
(See astrolib/pro/ct2lst.pro)
NAME:
CURS
PURPOSE:
Selects an X windows cursor shape
CALLING SEQUENCE:
curs ;Interactively select a cursor shape.
curs, sel ;Make the given CURSOR_STANDARD value the cursor
shape.
OPTIONAL INPUT:
sel - Either an integer giving the CURSOR_STANDARD value (usually an
even value between 0 and 152) indicating the cursor shape, or
a string from the following menu
a -- Up arrow
b -- Left-angled arrow
c -- Right-angled arrow
d -- Crosshair
e -- Finger pointing left
f -- Finger pointing right
g -- Narrow crosshair
h -- Cycle through all possible standard cursor shapes
The full list of available cursor values is given in
/usr/include/X11/cursorfont.h
OUTPUTS:
None.
RESTRICTIONS:
Uses the CURSOR_STANDARD keyword of the DEVICE procedure. Although
this keyword is available in Windows IDL, the values
used by this procedure are specific to the X windows device.
PROCEDURE:
If the user supplies a valid cursor shape value, it is set. Otherwise,
an interactive command loop is entered; it will continue until a valid
value is given.
MODIFICATION HISTORY:
Converted to VAX 3100 workstations / IDL V2. M. Greason, STX, May 1990.
Avoid bad cursor parameter values W. Landsman February, 1991
Don't change value of input param W. Landsman August 1995
Use SIZE(/TNAME) instead of DATATYPE() W. Landsman October 2001
(See astrolib/pro/curs.pro)
NAME:
CURVAL
PURPOSE:
Cursor controlled display of image intensities and astronomical coords
EXPLANATION
CURVAL displays different information depending whether the user
supplied an image array, and/or a FITS header array
Note that in the usual truecolor mode, the byte intensity returned by
CURVAL does not correspond to the byte scaled image value but rather
returns the maximum value in each color gun.
CALLING SEQUENCE(S):
curval ;Display x,y and byte intensity (inten)
curval, im ;Display x,y,inten, and also pixel value (from image array)
curval, hdr, [ im, OFFSET= , ZOOM=, FILENAME=, ALT=]
OPTIONAL INPUTS:
Hdr = FITS Header array
Im = Array containing values that are displayed. Any type.
OPTIONAL KEYWORD INPUTS:
ALT - single character 'A' through 'Z' or ' ' specifying an alternate
astrometry system present in the FITS header. The default is
to use the primary astrometry or ALT = ' '. If /ALT is set,
then this is equivalent to ALT = 'A'. See Section 3.3 of
Greisen & Calabretta (2002, A&A, 395, 1061) for information about
alternate astrometry keywords.
OFFSET - 2 element vector giving the location of the image pixel (0,0)
on the window display. OFFSET can be positive (e.g if the
image is centered in a larger window) or negative (e.g. if the
only the central region of an image much larger than the window
is being displayed.
Default value is [0,0], or no offset.
ZOOM - Scalar specifying the magnification of the window with respect
to the image variable. Use, for example, if image has been
REBINed before display.
FILENAME = name of file to where CURVAL data can be saved.
Data will only be saved if left or center mouse button
are pressed.
OUTPUTS:
None.
SIDE EFFECTS:
X and Y values, etc., of the pixel under the cursor are constantly
displayed.
Pressing left or center mouse button prints a line of output, and
starts a new line.
Pressing right mouse button exits the procedure.
If the keyword FILENAME is defined, the date and time, and a heading
will be printed in the file before the data.
PROCEDURES CALLED:
ADSTRING(), EXTAST, GSSSXYAD, RADEC, SXPAR(), UNZOOM_XY, XY2AD
REVISION HISTORY:
Written, K. Rhode, STX May 1990
Added keyword FILENAME D. Alexander June 1991
Don't write to Journal file W. Landsman March 1993
Use astrometry structure W. Landsman Feb 1994
Modified for Mac IDL I. Freedman April 1994
Allow for zoomed or offset image W. Landsman Mar 1996
Proper rounding of zoomed pixel values W. Landsman/R. Hurt Dec. 1997
Remove unneeded calls to obsolete !ERR W. Landsman December 2000
Replace remaining !ERR calls with !MOUSE.BUTTON W. Landsman Jan 2001
Allow for non-celestial (e.g. Galactic) coordinates W. Landsman Apr 2003
Work if RA/Dec reversed in CTYPE keyword W. Landsman Feb. 2004
Always call UNZOOM_XY for MOUSSE compatibility W. Landsman Sep. 2004
Added ALT keyword W. Landsman October 2004
Always test if offset/zoom supplied W. Landsman Feb 2008
(See astrolib/pro/curval.pro)
NAME: DAOERF PURPOSE: Calulates the intensity, and derivatives, of a 2-d Gaussian PSF EXPLANATION: Corrects for the finite size of a pixel by integrating the Gaussian over the size of the pixel. Used in the IDL-DAOPHOT sequence. CALLING SEQUENCE: DAOERF, XIN, YIN, A, F, [ PDER ] INPUTS: XIN - input scalar, vector or array, giving X coordinate values YIN - input scalar, vector or array, giving Y coordinate values, must have same number of elements as XIN. A - 5 element parameter array describing the Gaussian A(0) - peak intensity A(1) - X position of peak intensity (centroid) A(2) - Y position of peak intensity (centroid) A(3) - X sigma of the gaussian (=FWHM/2.345) A(4) - Y sigma of gaussian OUTPUTS: F - array containing value of the function at each (XIN,YIN) The number of output elements in F and PDER is identical with the number of elements in X and Y OPTIONAL OUTPUTS: PDER - 2 dimensional array of size (NPTS,5) giving the analytic derivative at each value of F with respect to each parameter A. REVISION HISTORY: Written: W. Landsman October, 1987 Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/daoerf.pro)
NAME:
DAO_VALUE
PURPOSE:
Returns the value of a DAOPHOT point-spread function at a set of points.
EXPLANATION:
The value of the point-spread function is the sum of a
two-dimensional integral under a bivariate Gaussian function, and
a value obtained by interpolation in a look-up table. DAO_VALUE will
optionally compute the derivatives wrt X and Y
CALLING SEQUENCE:
Result = DAO_VALUE( xx, yy, gauss, psf, [ dvdx, dvdy ] )
INPUTS:
XX,YY - the real coordinates of the desired point relative
to the centroid of the point-spread function.
GAUSS - 5 element vector describing the bivariate Gaussian
GAUSS(0)- the peak height of the best-fitting Gaussian profile.
GAUSS(1,2) - x and y offsets from the centroid of the point-spread
function to the center of the best-fitting Gaussian.
GAUSS(3,4) - the x and y sigmas of the best-fitting Gaussian.
PSF - a NPSF by NPSF array containing the look-up table.
OUTPUTS:
RESULT - the computed value of the point-spread function at
a position XX, YY relative to its centroid (which
coincides with the center of the central pixel of the
look-up table).
OPTIONAL OUTPUTS:
DVDX,DVDY - the first derivatives of the composite point-spread
function with respect to x and y.
NOTES
although the arguments XX,YY of the function DAO_VALUE
are relative to the centroid of the PSF, the function RINTER which
DAO_VALUE calls requires coordinates relative to the corner of the
array (see code).
PROCEDURES CALLED:
DAOERF, RINTER()
REVISON HISTORY:
Adapted to IDL by B. Pfarr, STX, 11/17/87 from 1986 STSDAS version
of DAOPHOT
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/dao_value.pro)
NAME:
DATE
PURPOSE:
Convert day-of-year to a DD-MMM-YYYY string
CALLING SEQUENCE:
D_String = DATE(Year, day )
INPUTS:
Year - Integer scalar specifying the year. If the year contains only
two digits, then it is assumed to indicate the number of
years after 1900.
Day - Integer scalar giving number of days after Jan 0 of the
specified year. Can be larger than 366
OUTPUTS:
D_String - String giving date in format '13-MAR-1986'
RESTRICTIONS:
Will not work for years before 100 AD
EXAMPLE:
IDL> print, date(1997,279)
'6-Oct-1997'
MODIFICATION HISTORY:
D.M. fecit 24 October,1983
Work for years outside of the 19th century W. Landsman September 1997
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/date.pro)
NAME:
DATE_CONV
PURPOSE:
Procedure to perform conversion of dates to one of three possible formats.
EXPLANATION:
The following date formats are allowed
format 1: real*8 scalar encoded as:
year*1000 + day + hour/24. + min/24./60 + sec/24./60/60
where day is the day of year (1 to 366)
format 2: Vector encoded as:
date[0] = year (eg. 2005)
date[1] = day of year (1 to 366)
date[2] = hour
date[3] = minute
date[4] = second
format 3: string (ascii text) encoded as
DD-MON-YEAR HH:MM:SS.SS
(eg. 14-JUL-2005 15:25:44.23)
OR
YYYY-MM-DD HH:MM:SS.SS (ISO standard)
(eg. 1987-07-14 15:25:44.23 or 1987-07-14T15:25:44.23)
format 4: three element vector giving spacecraft time words
from a Hubble Space Telescope (HST) telemetry packet. Based on
total number of secs since midnight, JAN. 1, 1979
format 5: Julian day. As this is also a scalar, like format 1,
the distinction between the two on input is made based on their
value. Numbers > 2300000 are interpreted as Julian days.
CALLING SEQUENCE
results = DATE_CONV( DATE, TYPE )
INPUTS:
DATE - input date in one of the possible formats. Must be scalar.
TYPE - type of output format desired. If not supplied then
format 3 (real*8 scalar) is used.
valid values:
'REAL' - format 1
'VECTOR' - format 2
'STRING' - format 3
'FITS' - YYYY-MM-DDTHH:MM:SS.SS'
'JULIAN' - Julian date
'MODIFIED' - Modified Julian date (JD-2400000.5)
TYPE can be abbreviated to the single character strings 'R',
'V', 'S', 'F', 'J', and 'M'.
Nobody wants to convert TO spacecraft time (I hope!)
OUTPUTS:
The converted date is returned as the function value.
EXAMPLES:
IDL> print,date_conv('2006-03-13 19:58:00.00'),f='(f15.5)'
2006072.83194
IDL> print,date_conv( 2006072.8319444d,'F')
2006-03-13T19:58:00.00
IDL> print,date_conv( 2006072.8319444d,'V')
2006.00 72.0000 19.0000 57.0000 59.9962
IDL> print,date_conv( 2006072.8319444d,'J'), f='(f15.5)'
2453808.33194
HISTORY:
version 1 D. Lindler July, 1987
adapted for IDL version 2 J. Isensee May, 1990
Made year 2000 compliant; allow ISO format input jls/acc Oct 1998
DJL/ACC Jan 1998, Modified to work with dates such as 6-JAN-1996 where
day of month has only one digit.
DJL, Nov. 2000, Added input/output format YYYY-MM-DDTHH:MM:SS.SS
Replace spaces with '0' in output FITS format W.Landsman April 2006
Added Julian date capabilities on input and output. M.Perrin, July 2007
Removed spurious /WARN keyword to MESSAGE W.L. Feb 2012
(See astrolib/pro/date_conv.pro)
NAME:
DAYCNV
PURPOSE:
Converts Julian dates to Gregorian calendar dates
CALLING SEQUENCE:
DAYCNV, XJD, YR, MN, DAY, HR
INPUTS:
XJD = Julian date, positive double precision scalar or vector
OUTPUTS:
YR = Year (Integer)
MN = Month (Integer)
DAY = Day (Integer)
HR = Hours and fractional hours (Real). If XJD is a vector,
then YR,MN,DAY and HR will be vectors of the same length.
EXAMPLE:
IDL> DAYCNV, 2440000.D, yr, mn, day, hr
yields yr = 1968, mn =5, day = 23, hr =12.
WARNING:
Be sure that the Julian date is specified as double precision to
maintain accuracy at the fractional hour level.
METHOD:
Uses the algorithm of Fliegel and Van Flandern (1968) as reported in
the "Explanatory Supplement to the Astronomical Almanac" (1992), p. 604
Works for all Gregorian calendar dates with XJD > 0, i.e., dates after
-4713 November 23.
REVISION HISTORY:
Converted to IDL from Yeoman's Comet Ephemeris Generator,
B. Pfarr, STX, 6/16/88
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/daycnv.pro)
NAME:
DBBUILD
PURPOSE:
Build a database by appending new values for every item.
EXPLANATION:
The database must be opened for update (with DBOPEN) before calling
DBBUILD. This version for IDL V6.1 or later.
CALLING SEQUENCE:
DBBUILD, [ v1, v2, v3, v4......v50, /NOINDEX, /SILENT, STATUS = ]
INPUTS:
v1,v2....v50 - vectors containing values for all items in the database.
V1 contains values for the first item, V2 for the second, etc.
The number of vectors supplied must equal the number of items
(excluding entry number) in the database. The number of elements
in each vector should be the same. A multiple valued item
should be dimensioned NVALUE by NENTRY, where NVALUE is the number
of values, and NENTRY is the number of entries.
OPTIONAL INPUT KEYWORDS:
/NOINDEX - If this keyword is supplied and non-zero then DBBUILD will
*not* create an indexed file. Useful to save time if
DBBUILD is to be called several times and the indexed file need
only be created on the last call
/SILENT - If the keyword SILENT is set and non-zero, then DBBUILD
will not print a message when the index files are generated
OPTIONAL OUTPUT KEYWORD:
STATUS - Returns a status code denoting whether the operation was
successful (1) or unsuccessful (0). Useful when DBBUILD is
called from within other applications.
EXAMPLE:
Suppose a database named STARS contains the four items NAME,RA,DEC, and
FLUX. Assume that one already has the four vectors containing the
values, and that the database definition (.DBD) file already exists.
IDL> !PRIV=2 ;Writing to database requires !PRIV=2
IDL> dbcreate,'stars',1,1 ;Create database (.DBF) & index (.DBX) file
IDL> dbopen,'stars',1 ;Open database for update
IDL> dbbuild,name,ra,dec,flux ;Write 4 vectors into the database
NOTES:
Do not call DBCREATE before DBBUILD if you want to append entries to
an existing database
DBBUILD checks that each value vector matches the idl type given in the
database definition (..dbd) file, and that character strings are the
proper length.
PROCEDURE CALLS:
DBCLOSE, DBINDEX, DBXPUT, DBWRT, IS_IEEE_BIG()
REVISION HISTORY:
Written W. Landsman March, 1989
Added /NOINDEX keyword W. Landsman November, 1992
User no longer need supply all items W. Landsman December, 1992
Added STATUS keyword, William Thompson, GSFC, 1 April 1994
Added /SILENT keyword, William Thompson, GSFC, October 1995
Allow up to 30 items, fix problem if first item was multiple value
W. Landsman GSFC, July 1996
Faster build of external databases on big endian machines
W. Landsman GSFC, November 1997
Use SIZE(/TNAME) for error mesage display W.Landsman July 2001
Fix message display error introduced July 2001 W. Landsman Oct. 2001
Make sure error message appears even if !QUIET is set W.L November 2006
Major rewrite to use SCOPE_VARFETCH, accept 50 input items
W. Landsman November 2006
Fix warning if parameters have different # of elements W.L. May 2010
Fix warning if scalar parameter supplied W.L. June 2010
Fix for when first parameter is multi-dimensioned W.L. July 2010
Check data type of first parameter W.L. Jan 2012
(See astrolib/pro/dbbuild.pro)
NAME:
DBCIRCLE
PURPOSE:
Find sources in a database within specified radius of specified center
EXPLANATION:
Database must include items named 'RA' (in hours) and 'DEC' (in degrees)
and must have previously been opened with DBOPEN
CALLING SEQUENCE:
list = DBCIRCLE( ra_cen, dec_cen, [radius, dis, sublist, /SILENT,
/GALACTIC, TO_B1950, /TO_J2000, COUNT= ] )
INPUTS:
RA_CEN - Right ascension of the search center in decimal HOURS, scalar
DEC_CEN - Declination of the search center in decimal DEGREES, scalar
RA_CEN and DEC_CEN should be in the same equinox as the
currently opened catalog.
OPTIONAL INPUT:
RADIUS - Radius of the search field in arc minutes, scalar.
DBCIRCLE prompts for RADIUS if not supplied.
SUBLIST - Vector giving entry numbers in currently opened database
to be searched. Default is to search all entries
OUTPUTS:
LIST - Vector giving entry numbers in the currently opened catalog
which have positions within the specified search circle
LIST is set to -1 if no sources fall within the search circle
OPTIONAL OUTPUT
DIS - The distance in arcminutes of each entry specified by LIST
to the search center (given by RA_CEN and DEC_CEN)
OPTIONAL KEYWORD INPUT:
/GALACTIC - if set, then the first two parameters are interpreted as
Galactic coordinates in degrees, and is converted internally
to J2000 celestial to search the database.
/SILENT - If this keyword is set, then DBCIRCLE will not print the
number of entries found at the terminal
/TO_J2000 - If this keyword is set, then the entered coordinates are
assumed to be in equinox B1950, and will be converted to
J2000 before searching the database
/TO_B1950 - If this keyword is set, then the entered coordinates are
assumed to be in equinox J2000, and will be converted to
B1950 before searching the database
NOTE: The user must determine on his own whether the database
is in B1950 or J2000 coordinates.
OPTIONAL KEYWORD OUTPUT:
COUNT - - Integer scalar giving the number of valid matches
METHOD:
A DBFIND search is first performed on a square area of given radius.
The list is the restricted to a circular area by using GCIRC to
compute the distance of each object to the field center.
RESTRICTIONS;
The database must have items 'RA' (in hours) and 'DEC' (in degrees).
Alternatively, the database could have items RA_OBJ and DEC_OBJ
(both in degrees)
EXAMPLE:
Find all Hipparcos stars within 40' of the nucleus of M33
(at J2000 1h 33m 50.9s 30d 39' 36.7'')
IDL> dbopen,'hipparcos'
IDL> list = dbcircle( ten(1,33,50.9), ten(3,39,36.7), 40)
PROCEDURE CALLS:
BPRECESS, DBFIND(), DBEXT, DB_INFO(), GCIRC, GLACTC, JPRECESS
REVISION HISTORY:
Written W. Landsman STX January 1990
Fixed search when crossing 0h July 1990
Spiffed up code a bit October, 1991
Leave DIS vector unchanged if no entries found W. Landsman July 1999
Use maximum declination, rather than declination at field center to
correct RA for latitude effect W. Landsman September 1999
Added COUNT, GALACTIC keywords W. Landsman December 2008
Fix problem when RA range exceeds 24h W. Landsman April 2009
Work as advertised for RA_OBJ field W. Landsman June 2010
Fix occasional problem when crossing 0h E. Donoso/W.Landsman Jan 2013
(See astrolib/pro/dbcircle.pro)
NAME:
DBCLOSE
PURPOSE:
procedure to close a data base file
CALLING SEQUENCE:
dbclose
INPUTS:
None
OUTPUTS
None
SIDE EFFECTS:
the data base files currently opened are closed
PROCEDURE CALLS:
DB_INFO(), HOST_TO_IEEE
HISTORY:
version 2 D. Lindler Oct. 1987
For IDL version 2 August 1990
William Thompson, GSFC/CDS (ARC), 30 May 1994
Added support for external (IEEE) data format
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/dbclose.pro)
NAME:
DBCOMPARE
PURPOSE:
Display two entries in an IDL database side by side in a column format
CALLING SEQUENCE:
dbcompare, list1, list2, [items, TEXTOUT= , /DIFF]
INPUTS:
list1 - Integer scalar giving first entry number to be compared.
list2 - Integer scalar giving second entry number to be compared.
OPTIONAL INPUT-OUTPUT:
items - items to be compared, if not supplied then all items will be
compared. The items can be specified in any of the following ways:
form 1 scalar string giving item(s) as list of names
separated by commas
form 2 string array giving list of item names
form 3 string of form '$filename' giving name
of text file containing items (one item per line) line)
form 4 integer scalar giving single item number or
integer vector list of item numbers
form 5 Null string specifying interactive selection. This
is the default if 'items' is not supplied
form 6 '*' select all items (= default)
If items was undefined or a null string on input, then
on output it will contain the items interactively selected.
OPTIONAL INPUT KEYWORDS:
/DIFF - If this keyword is set and non-zero, then only the items
in the database that differ will be printed
TEXTOUT - Scalar Integer (1-7) Used to determine output device. See
TEXTOPEN for more info.
SYSTEM VARIABLES:
Output device controlled by non-standard system variable !TEXTOUT, if
TEXTOUT keyword is not used.
EXAMPLE:
Display entries 3624 and 3625 in column form showing only the items
that differ.
IDL> dbcompare,3624,3625,/diff
PROCEDURES USED:
DB_INFO(), DB_ITEM, DB_ITEM_INFO(), DBRD, DBXVAL()
TEXTOPEN, TEXTCLOSE
HISTORY:
Written, W. Landsman July 1996
Fix documentation, add Syntax display W. Landsman November 1998
Replace DATATYPE() with size(/TNAME) W. Landsman November 2001
Assume since V5.5, remove VMS call W. Landsman September 2006
Fix problem with multiple values when /DIFF set W. Landsman April 2007
(See astrolib/pro/dbcompare.pro)
NAME:
DBCREATE
PURPOSE:
Create a new data base (.dbf), index (.dbx) or description (.dbh) file
EXPLANATION:
A database definition (.dbd) file must already exist in the current
directory or in a ZDBASE directory. The new .dbf, .dbx and/or .dbh
files will be written to the same directory. So if the .dbd file is
in a ZDBASE directory, then the user must have write privilege to that
directory
This version allows record length to be larger than 32767 bytes
CALLING SEQUENCE:
dbcreate, name,[ newindex, newdb, maxitems] [,/EXTERNAL, MAXENTRY=]
INPUTS:
name- name of the data base (with no qualifier), scalar string.
The description will be read from the file "NAME".dbd
Maximum length of name is 19 characters.
OPTIONAL INPUTS:
newindex - if non-zero then a new index file is created,
otherwise it is assumed that changes do not affect the
index file. (default=0)
newdb - if non-zero then a new data base file (.dbf) will
be created. Otherwise changes are assumed not to affect
the file's present format.
maxitems - maximum number of items in data base.
If not supplied then the number of items is
limited to 200.
OUTPUTS:
NONE.
OPTIONAL INPUT KEYWORDS:
external - If set, then the database is written with an external data
representation. This allows the database files to be used on
any computer platform, e.g. through NFS mounts, but some
overhead is added to reading the files. The default is to
write the data in the native format of the computer being used.
This keyword is only paid attention to if NEWDB or NEWINDEX
are nonzero. Otherwise, the database is opened to find
out if it uses external representation or not.
Extreme caution should be used if this keyword is used with
only NEWINDEX set to a nonzero value. This mode is allowed so
that databases written on machines which already use the
external data representation format, e.g. Sun workstations, to
be marked external so that other machines can read them.
MAXENTRY - positive integer giving the maximum number of entries in the
database (needed to adjust the size of the index file). This
keyword can be used to supercede the #maxentries line in the
.dbd file (the larger of the two numbers will be used).
PROCEDURE CALLS:
GETTOK(), FIND_WITH_DEF(), ZPARCHECK
RESTRICTIONS:
If newdb=0 is not specified, the changes to the .dbd file can
not alter the length of the records in the data base file.
and may not alter positions of current fields in the file.
permissible changes are:
1) utilization of spares to create a item or field
2) change in field name(s)
3) respecification of index items
4) changes in default print formats
5) change in data base title
6) changes in pointer specification to other data
data bases
!priv must be 2 or greater to execute this routine.
SIDE EFFECTS:
data base description file ZDBASE:name.dbh is created
and optionally ZDBASE:name.dbf (data file) and
ZDBASE.dbx (index file) if it is a new data base.
REVISION HISTORY:
D. Lindler, GSFC/HRS, October 1987
Modified: Version 1, William Thompson, GSFC, 29 March 1994
Version 2, William Thompson, GSFC/CDS (ARC), 28 May 1994
Added EXTERNAL keyword.
Version 4, William Thompson, GSFC, 3 November 1994
Modified to allow ZDBASE to be a path string.
8/14/95 JKF/ACC - allow EXTERNAL data for newindex OR newdb modes.
Make sure all databases closed before starting W. Landsman June 1997
Added new unsigned and 64 bit integer datatypes W. Landsman July 2001
Make sure to use lowercase filenames on Unix W. Landsman May 2006
Added MAXENTRY keyword W. Landsman July 2006
Assume since V5.5, remove obsolete keywords to OPEN W. Landsman Sep2006
No longer required to be a ZDBASE directory W. Landsman Feb 2008
Fix Feb 2008 bug when files are in current dir W. L. May 2008
Fix May 2008 bug when files are not in current dir (sigh) W. L. May 2008
Warn if database length exceeds 32767 bytes W.L. Dec 2009
Remove spurious warning that database name is too long W.L. April 2010
Support entry lengths larger than 32767 bytes W.L. Oct. 2010
Better testing for valid print formats W.L. Nov 2010
Fix problem where descriptions of different items could overlap
E.Shaya/W.L. Oct. 2012
(See astrolib/pro/dbcreate.pro)
NAME:
DBDELETE
PURPOSE:
Deletes specified entries from data base
CALLING SEQUENCE:
DBDELETE, list, [ name, /DEBUG ]
INPUTS:
list - list of entries to be deleted, scalar or vector
name - optional name of data base, scalar string. If not specified
then the data base file must be previously opened for update
by DBOPEN.
OPERATIONAL NOTES:
!PRIV must be at least 3 to execute.
SIDE EFFECTS:
The data base file (ZDBASE:name.dbf) is modified by removing the
specified entries and reordering the remaining entry numbers
accordingly (ie. if you delete entry 100, it will be replaced
by entry 101 and the database will contain 1 less entry.
EXAMPLE:
Delete entries in a database STARS where RA=DEC = 0.0
IDL> !PRIV= 3 ;Set privileges
IDL> dbopen,'STARS',1 ;Open for update
IDL> list = dbfind('ra=0.0,dec=0.0') ;Obtain LIST vector
IDL> dbdelete, list ;Delete specified entries from db
NOTES:
The procedure is rather slow because the entire database is re-
created with the specified entries deleted.
OPTIONAL KEYWORD INPUT:
DEBUG - if this keyword is set and non-zero, then additional
diagnostics will be printed as each entry is deleted.
COMMON BLOCKS:
DBCOM
PROCEDURE CALLS:
DBINDEX, DB_INFO(), DBOPEN, DBPUT, ZPARCHECK
HISTORY
Version 2 D. Lindler July, 1989
Updated documentation W. Landsman December 1992
William Thompson, GSFC, 28 February 1995
Fixed bug when external representation used.
Fixed for case where second parameter supplied W. Landsman April 1996
Use keyword DEBUG rather than !DEBUG W. Landsman May 1997
Don't call DBINDEX if no indexed items W. Landsman May 2006
Use TRUNCATE_LUN if V5.6 or later W. Landsman Sep 2006
Fix problem when deleting last entry W. Landsman Mar 2007
Assume since V5.6 so TRUNCATE_LUN is available W. Landsman
(See astrolib/pro/dbdelete.pro)
NAME:
DBEDIT
PURPOSE:
Interactively edit specified fields in an IDL database.
EXPLANATION:
The value of each field is displayed, and the user has the option
of changing or keeping the value. Widgets will be used if they
are available.
CALLING SEQUENCE:
dbedit, list, [ items ]
INPUTS:
list - scalar or vector of database entry numbers. Set list = 0 to
interactively add a new entry to a database. Set list = -1 to edit
all entries.
OPTIONAL INPUTS:
items - list of items to be edited. If omitted, all fields can be
edited.
KEYWORDS:
BYTENUM = If set, treat byte variables as numbers instead of
characters.
COMMON BLOCKS:
DB_COM -- contains information about the opened database.
DBW_C -- contains information intrinsic to this program.
SIDE EFFECTS:
Will update the database files.
RESTRICTIIONS:
Database must be opened for update prior to running
this program. User must be running DBEDIT from an
account that has write privileges to the databases.
If one is editing an indexed item, then after all edits are complete,
DBINDEX will be called to reindex the entire item. This may
be time consuming.
Cannot be used to edit items with multiple values
EXAMPLE:
Suppose one had new parallaxes for all stars fainter than 5th magnitude
in the Yale Bright Star Catalog and wanted to update the PRLAX and
PRLAX_CODE fields with these new numbers
IDL> !priv=2
IDL> dbopen, 'yale_bs', 1 ;Open catalog for update
IDL> list = dbfind( 'v>5') ;Find fainter than 5th magnitude
IDL> dbedit, list, 'prlax, prlax_code' ;Manual entry of new values
PROCEDURE:
(1) Use the cursor and point to the value you want to edit.
(2) Type the new field value over the old field value.
(3) When you are done changing all of the field values for each entry
save the entry to the databases by pressing 'SAVE ENTRY TO DATABASES'.
Here all of the values will be checked to see if they are the correct
data type. If a field value is not of the correct data type, it will
not be saved.
Use the buttons "PREV ENTRY" and "NEXT ENTRY" to move between entry
numbers. You must save each entry before going on to another entry in
order for your changes to be saved.
Pressing "RESET THIS ENTRY" will remove any unsaved changes to the
current entry.
REVISION HISTORY:
Adapted from Landsman's DBEDIT
added widgets, Melissa Marsh, HSTX, August 1993
do not need to press return after entering each entry,
fixed layout problem on SUN,
Melissa Marsh, HSTX, January 1994
Only updates the fields which are changed. Joel Offenberg, HSTX, Mar 94
Corrected test for changed fields Wayne Landsman HSTX, Mar 94
Removed a couple of redundant statements W. Landsman HSTX Jan 96
Converted to IDL V5.0 W. Landsman September 1997
Replace DATAYPE() with size(/TNAME) W. Landsman November 2001
Work for entry numbers > 32767 W. Landsman December 2001
Added /BYTENUM William Thompson 13-Mar-2006
Use DIALOG_MESSAGE for error messages W. Landsman April 2006
Assume since V5.5, remove VMS support W. Landsman Sep 2006
(See astrolib/pro/dbedit.pro)
NAME:
DBEDIT_BASIC
PURPOSE:
Subroutine of DBEDIT_BASIC to edit a database on a dumb terminal.
EXPLANATION:
Interactively edit specified fields in a database. The
value of each field is displayed, and the user has the option
of changing or keeping the value.
CALLING SEQUENCE:
dbedit_basic, list, [ items ]
INPUTS:
list - scalar or vector of database entry numbers. Set LIST=0
to interactively add a new entry to a database.
OPTIONAL INPUTS
items - list of items to be edited. If not supplied, then the
value of every field will be displayed.
NOTES:
(1) Database must be opened for update (dbopen,,1) before
calling DBEDIT_BASIC. User must have write privileges on the database
files.
(2) User gets a second chance to look at edited values, before
they are actually written to the database
PROMPTS:
The item values for each entry to be edited are first displayed
User is the asked "EDIT VALUES IN THIS ENTRY (Y(es), N(o), or Q(uit))?
If user answers 'Y' or hits RETURN, then each item is displayed
with its current value, which the user can update. If user answered
'N' then DBEDIT_BASIC skips to the next entry. If user answers 'Q'
then DBEDIT will exit, saving all previous changes.
EXAMPLE:
Suppose V magnitudes (V_MAG) in a database STARS with unknown values
were assigned a value of 99.9. Once the true values become known, the
database can be edited
IDL> !PRIV=2 & dbopen,'STARS',1 ;Open database for update
IDL> list = dbfind('V_MAG=99.9') ;Get list of bad V_MAG values
IDL> dbedit,list,'V_MAG' ;Interactively insert good V_MAG values
REVISION HISTORY:
Written W. Landsman STX April, 1989
Rename DBEDIT_BASIC from DBEDIT July, 1993
Converted to IDL V5.0 W. Landsman September 1997
Change DATATYPE() to size(/TNAME) W. Landsman November 2001
(See astrolib/pro/dbedit_basic.pro)
NAME:
DBEXT
PURPOSE:
Extract values of up to 12 items from an IDL database
EXPLANATION:
Procedure to extract values of up to 12 items from
data base file, and place into IDL variables
CALLING SEQUENCE:
dbext,list,items,v1,[v2,v3,v4,v5,v6,v7,v8,v9,v10,v11,v12]
INPUTS:
list - list of entry numbers to be printed, vector or scalar
If list = -1, then all entries will be extracted.
list may be converted to a vector by DBEXT
items - standard item list specification. See DBPRINT for
the 6 different ways that items may be specified.
OUTPUTS:
v1...v12 - the vectors of values for up to 12 items.
EXAMPLE:
Extract all RA and DEC values from the currently opened database, and
place into the IDL vectors, IDLRA and IDLDEC.
IDL> DBEXT,-1,'RA,DEC',idlra,idldec
HISTORY
version 2 D. Lindler NOV. 1987
check for INDEXED items W. Landsman Feb. 1989
Converted to IDL V5.0 W. Landsman September 1997
Avoid EXECUTE() call for V6.1 or later W. Landsman December 2006
Assume since V6.1 W. Landsman June 2009
(See astrolib/pro/dbext.pro)
NAME:
DBEXT_DBF
PURPOSE:
Subroutine of DBEXT to extract values of up to 18 items from a database
EXPLANATION:
This is a subroutine of DBEXT, which is the routine a user should
normally use.
CALLING SEQUENCE:
dbext_dbf,list,dbno,sbyte,nbytes,idltype,nval,v1,[ v2,v3,v4,v5,v6,v7,
v8,v9,v10,v11,v12,v13,v14,v15,v16,v17,v18 ITEM_DBNO = ]
INPUTS:
list - list of entry numbers to extract desired items. It is the
entry numbers in the primary data base unless dbno is greater
than or equal to -1. In that case it is the entry number in
the specified data base.
dbno - number of the opened db file
if set to -1 then all data bases are included
sbyte - starting byte in the entry. If single data base then it must
be the starting byte for that data base only and not the
concatenation of db records
nbytes - number of bytes in the entry
idltype - idl data type of each item to be extracted
nval - number of values per entry of each item to be extracted
OUTPUTS:
v1...v18 - the vectors of values for up to 18 items
OPTIONAL INPUT KEYWORD:
item_dbno - A vector of the individual database numbers for each item.
Simplifies the code for linked databases
PROCEDURE CALLS:
DB_INFO(), DB_ITEM_INFO(), DBRD, DBXVAL(), IS_IEEE_BIG(), IEEE_TO_HOST
HISTORY
version 1 D. Lindler Nov. 1987
Extract multiple valued entries W. Landsman May 1989
William Thompson, GSFC/CDS (ARC), 1 June 1994
Added support for external (IEEE) representation.
Work with multiple element string items W. Landsman August 1995
Increase speed for external databases on IEEE machines WBL August 1996
IEEE conversion implemented on blocks of entries using BIG
Added keyword ITEM_DBNO R. Schwartz, GSFC/SDAC, August 1996
Return a vector even if only 1 value W. Thompson October 1996
Change variable name of BYTESWAP to BSWAP W. Thompson Mar 1997
Use /OVERWRITE with reform W. Landsman May 1997
Increase maximum number of items to 18 W. Landsman November 1999
2 May 2003, W. Thompson, Use DBXVAL with BSWAP instead of IEEE_TO_HOST.
Avoid EXECUTE() for V6.1 or later W. Landsman Jan 2007
Assume since V6.1 W. Landsman June 2009
Change arrays to LONG to support entries >32767 bytes WL Oct 2010
(See astrolib/pro/dbext_dbf.pro)
NAME:
DBEXT_IND
PURPOSE:
routine to read a indexed item values from index file
CALLING SEQUENCE:
dbext_ind,list,item,dbno,values
INPUTS:
list - list of entry numbers to extract values for
(if it is a scalar, values for all entries are extracted)
item - item to extract
dbno - number of the opened data base
OUTPUT:
values - vector of values returned as function value
HISTORY:
version 1 D. Lindler Feb 88
Faster processing of string values W. Landsman April, 1992
William Thompson, GSFC/CDS (ARC), 30 May 1994
Added support for external (IEEE) data format
Allow multiple valued (nonstring) index items W. Landsman November 2000
Use 64bit integer index for large databases W. Landsman February 2001
Fix sublisting of multiple valued index items W. Landsman March 2001
Check whether any supplied entries are valid W. Landsman Jan 2009
(See astrolib/pro/dbext_ind.pro)
NAME:
DBFIND()
PURPOSE:
Search data base for entries with specified characteristics
EXPLANATION:
Function to search data base for entries with specified
search characteristics.
CALLING SEQUENCE:
result = dbfind(spar,[ listin, /SILENT, /FULLSTRING, ERRMSG=, Count = ])
INPUTS:
spar - search_parameters (string)...each search parameter
is of the form:
option 1) min_val < item_name < max_val
option 2) item_name = value
option 3) item_name = [value_1, value_10]
Note: option 3 is also the slowest.
option 4) item_name > value
option 5) item_name < value
option 6) item_name = value(tolerance) ;eg. temp=25.0(5.2)
option 7) item_name ;must be non-zero
Multiple search parameters are separated by a comma.
eg. 'cam_no=2,14 is interpreted as greater than or equal.
RA and DEC keyfields are stored as floating point numbers
in the data base may be entered as HH:MM:SEC and
DEG:MIN:SEC. Where:
HH:MM:SEC equals HH + MM/60.0 + SEC/3600.
DEG:MIN:SEC equals DEG + MIN/60.0 + SEC/3600.
For example:
40:34:10.5 < dec < 43:25:19 , 8:22:1.0 < ra < 8:23:23.0
Specially encoded date/time in the data base may
be entered by CCYY/DAY:hr:min:sec which is
interpreted as
CCYY*1000+DAY+hr/24.0+min/24.0/60.+sec/24.0/3600.
If a two digit year is supplied and YY GE 40 then it is
understood to refer to year 1900 +YY; if YY LT 40 then it is
understood to refer to year 2000 +YY
For example
1985/201:10:35:3032767 bytes W.L. Oct. 2010
(See astrolib/pro/dbfind.pro)
NAME:
DBFIND_ENTRY
PURPOSE:
Subroutine of DBFIND to perform an entry number search
EXPLANATION:
This is a subroutine of dbfind and is not a standalone procedure
It performs a entry number search.
CALLING SEQUENCE:
dbfind_entry, type, svals, nentries, values, [COUNT = ]
INPUTS:
type - type of search (output from dbfparse)
svals - search values (output from dbfparse)
values - array of values to search
OUTPUT:
good - indices of good values
OPTIONAL OUTPUT KEYWORD:
Count - integer scalar giving the number of valid matches
SIDE EFFECTS"
The obsolete system variable !err is set to number of good values
REVISION HISTORY:
D. Lindler July,1987
Fixed test for final entry number W. Landsman Sept. 95
Converted to IDL V5.0 W. Landsman September 1997
Added COUNT keyword, deprecate !ERR W. Landsman March 2000
Better checking of out of range values W. Landsman February 2002
(See astrolib/pro/dbfind_entry.pro)
NAME:
DBFIND_SORT
PURPOSE:
Subroutine of DBFIND to perform a search using sorted values
EXPLANATION:
This is a subroutine of dbfind and is not a standalone procedure
It is used to limit the search using sorted values
CALLING SEQUENCE:
dbfind_sort, it, type, svals, list, [/FULLSTRING, COUNT = ]
INPUT:
it - item number, scalar
type - type of search (output from dbfparse)
svals - search values (output from dbfparse)
INPUT/OUTPUT:
list - found entries
OPTIONAL INPUT KEYWORD:
/FULLSTRING - By default, one has a match if a search string is
included in any part of a database value (substring match).
But if /FULLSTRING is set, then all characters in the database
value must match the search string (excluding leading and
trailing blanks). Both types of string searches are case
insensitive.
OPTIONAL OUTPUT KEYWORD
Count - Integer scalar giving the number of matches found
SYSTEM VARIABLES:
The obsolete system variable !err is set to number of good values
!ERR = -2 for an invalid search
PROCEDURES CALLED:
DB_INFO(), DB_ITEM_INFO(), DBSEARCH()
REVISION HISTORY:
D. Lindler July,1987
William Thompson, GSFC/CDS (ARC), 30 May 1994
Added support for external (IEEE) data format
William Thompson, GSFC, 14 March 1995 Added keyword FULLSTRING
Minimize use of obsolete !ERR variable W. Landsman February 2000
Added COUNT keyword, deprecate !ERR W. Landsman March 2000
Use 64 bit integers V5.2 or later
Include new IDL unsigned & 64 bit integer datatypes W.Landsman July 2001
Make sure returned list vector is LONG W. Landsman August 2001
Work on string items W. Landsman November 2009
Don't use VALUE_LOCATE on a single value W. Landsman November 2009
Use VALUE_LOCATE even for equal values W. Landsman December 2009
Fix bug allowing negative FIRST values, William Thompson, 10 May 2010
(See astrolib/pro/dbfind_sort.pro)
NAME:
DBFPARSE
PURPOSE:
Parse the search string supplied to DBFIND. Not a standalone routine
CALLING SEQUENCE:
DBFPARSE, [ spar, items, stype, values ]
INPUTS:
spar - search parameter specification, scalar string
OUTPUTS:
items - list of items to search on
stype - search type, numeric scalar
0 item=values(j,0)
-1 item>values(j,0)
-2 item
(See astrolib/pro/dbfparse.pro)
DBGET
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NAME:
DBGET
PURPOSE:
Find entry numbers which contain specified values of a given item.
EXPLANATION:
DBGET() is useful as an alternative to DBFIND() when the desired
search values are not easily expressed as a string.
CALLING SEQUENCE:
list = dbget( item, values, [ listin ], /SILENT, /FULLSTRING )
INPUTS:
item - Item name or number
values - scalar or vector containing item values to search for.
OPTIONAL INPUTS:
listin - list of entries to be searched. If not supplied, or
set to -1, then all entries are searched
OUTPUT:
list - vector giving the entry number of entries containing desired
item values. The number of elements in LIST may be different
from that of VALUE, since a value might be located zero, once,
or many times in the database. Use the function DBMATCH if a
one to one correspondence is desired between VALUES and LIST.
OPTIONAL INPUT KEYWORDS:
/SILENT - If this keyword is set, then DBGET will not display
the number of entries found
/FULLSTRING - By default, one has a match if a search string is
included in any part of a database value (substring match).
But if /FULLSTRING is set, then all characters in the database
value must match the search string (excluding leading and
trailing blanks). Both types of string searches are case
insensitive.
OPTIONAL OUTPUT KEYWORD:
COUNT - Integer scalar giving the number of valid matches
RESTRICTIONS:
When linked databases are opened together, DBGET can only be used to
search on items in the primary database.
EXAMPLE:
Get info on selected HD stars in Bright Star catalogue
IDL> dbopen, 'YALE_BS'
IDL> hdno = [1141,2363,3574,4128,6192,6314,6668] ;Desired HD numbers
IDL> list = dbget( 'HD', hdno ) ;Get corresponding entry numbers
SYSTEM VARIABLES:
The obsolete system variable !ERR is set to number of entries found
REVISION HISTORY:
Written, W. Landsman STX February, 1989
William Thompson, GSFC, 14 March 1995 Added keyword FULLSTRING
Converted to IDL V5.0 W. Landsman September 1997
Added COUNT keyword, deprecate !ERR W. Landsman March 2000
Fix bug introduced March 2000 W. Landsman November 2000
Fix possible bug when sublist supplied W. Landsman August 2008
(See astrolib/pro/dbget.pro)
DBHELP
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NAME:
DBHELP
PURPOSE:
List available databases or items in the currently open database
EXPLANATION:
Procedure to either list available databases (if no database is
currently open) or the items in the currently open database.
CALLING SEQUENCE:
dbhelp, [ flag , TEXTOUT=, /SORT ]
INPUT:
flag - (optional) if set to nonzero then item or database
descriptions are also printed
default=0
If flag is a string, then it is interpreted as the
name of a data base (if no data base is opened) or a name
of an item in the opened data base. In this case, help
is displayed only for the particular item or database
OUTPUTS:
None
OPTIONAL INPUT KEYWORDS:
TEXTOUT - Used to determine output device. If not present, the
value of !TEXTOUT system variable is used (see TEXTOPEN )
textout=0 Nowhere
textout=1 if a TTY then TERMINAL using /more option
otherwise standard (Unit=-1) output
textout=2 if a TTY then TERMINAL without /more option
otherwise standard (Unit=-1) output
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file
textout=7 same as 3 but text is appended to .prt
file if it already exists.
textout = filename (default extension of .prt)
/SORT - If set and non-zero, then the help items will be displayed
sorted alphabetically. If more than one database is open,
then this keyword does nothing.
METHOD:
If no data base is opened then a list of data bases are
printed, otherwise the items in the open data base are printed.
If a string is supplied for flag and a data base is opened
flag is assumed to be an item name. The information for that
item is printed along with contents in a optional file
zdbase:dbname_itemname.hlp
if a string is supplied for flag and no data base is opened,
then string is assumed to be the name of a data base file.
only information for that file is printed along with an
optional file zdbase:dbname.hlp.
PROCEDURES USED:
DB_INFO(),DB_ITEM_INFO(),FIND_WITH_DEF(), TEXTOPEN, TEXTCLOSE, UNIQ()
IDL VERSION:
V5.3 or later (uses vectorized FDECOMP)
HISTORY:
Version 2 D. Lindler Nov 1987 (new db format)
Faster printing of title desc. W. Landsman May 1989
Keyword textout added, J. Isensee, July, 1990
Modified to work on Unix, D. Neill, ACC, Feb 1991.
William Thompson, GSFC/CDS (ARC), 1 June 1994
Added support for external (IEEE) representation.
William Thompson, GSFC, 3 November 1994
Modified to allow ZDBASE to be a path string.
Remove duplicate database names Wayne Landsman December 1994
8/17/95 jkf/acc - force lowercase filenames for .hlp files.
Added /SORT keyword J. Sandoval/W. Landsman October 1998
V5.3 version use vectorized FDECOMP W. Landsman February 2001
Recognize 64 bit, unsigned integer datatypes W. Landsman September 2001
Fix display of number of bytes with /SORT W. Landsman February 2002
Assume since V5.2 W. Landsman February 2002
Assume since V5.5 W. Landsman
(See astrolib/pro/dbhelp.pro)
DBINDEX
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NAME:
DBINDEX
PURPOSE:
Procedure to create index file for data base
CALLING SEQUENCE:
dbindex, [ items ]
OPTIONAL INPUT:
items - names or numbers of items to be index -- if not supplied,
then all indexed fields will be processed.
OUTPUT:
Index file .dbx is created on disk location ZDBASE:
OPERATIONAL NOTES:
(1) Data base must have been previously opened for update
by DBOPEN
(2) Only 18 items can be indexed at one time. If the database has
more than 18 items, then two separate calls to DBINDEX are needed.
PROCEDURES CALLED:
DBINDEX_BLK, DB_INFO(), DB_ITEM, DB_ITEM_INFO(), IEEE_TO_HOST,
IS_IEEE_BIG()
HISTORY:
version 2 D. Lindler Nov 1987 (new db format)
W. Landsman added optional items parameter Feb 1989
William Thompson, GSFC/CDS (ARC), 30 May 1994
Added support for external (IEEE) data format
Test if machine is bigendian W. Landsman May, 1996
Change variable name of BYTESWAP to BSWAP W. Thompson Mar, 1997
Increased number of fields to 15 W. Landsman June, 1997
Increase number of items to 18 W. Landsman November 1999
Allow multiple valued (nonstring) index items W. Landsman November 2000
Use 64 bit integers for V5.2 or later W. Landsman February 2001
Do not use EXECUTE() for V6.1 or later, improve efficiency
W. Landsman December 2006
Automatically enlarge .dbx file if needed, fix major bug in last
update W. Landsman Dec 2006
Assume since V6.1 W. Landsman June 2009
Allow sorted string items W. Landsman October 2009
(See astrolib/pro/dbindex.pro)
DBINDEX_BLK
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NAME:
DBINDEX_BLK
PURPOSE:
Subroutine of DBINDEX to create associated variable of correct datatype
EXPLANATION:
DBINDEX_BLK will offset into the file by a specified amount in
preparation for writing to the file. V5.2 or later
CALLING SEQUENCE:
res = dbindex_blk(unit, nb, bsz, ofb, dtype)
INPUTS:
unit The unit number assigned to the file.
nb The number of blocks to offset into the file.
bsz The size of each block, in bytes, to offset into the file.
ofb The offset into the block, in bytes.
dtype The IDL datatype as defined in the SIZE function
OUTPUTS:
res The returned variable. This is an associated variable.
RESTRICTIONS:
The file must have been previously opened.
MODIFICATION HISTORY:
Written by Michael R. Greason, STX, 14 June 1990.
Converted to IDL V5.0 W. Landsman September 1997
Use 64 bit integer for very large databases W. Landsman February 2001
Added new unsigned & 64bit integer datatypes W. Landsman July 2001
(See astrolib/pro/dbindex_blk.pro)
DBMATCH
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NAME:
DBMATCH
PURPOSE:
Find the entry number in a database for each element of item values
EXPLANATION:
DBMATCH() is especially useful for finding a one-to-one
correspondence between entries in different databases, and thus to
create the vector needed for database pointers.
CALLING SEQUENCE:
list = DBMATCH( item, values, [ listin, /FULLSTRING ] )
INPUTS:
ITEM - Item name or number, scalar
VALUES - scalar or vector containing item values to search for.
OPTIONAL INPUTS:
LISTIN - list of entries to be searched. If not supplied, or
set to -1, then all entries are searched
OUTPUT:
LIST - vector of entry numbers with the same number of elements as
VALUES. Contains a value of 0 wherever the corresponding item
value was not found.
OPTIONAL INPUT:
/FULLSTRING - By default, one has a match if a search string is
included in any part of a database value (substring match).
But if /FULLSTRING is set, then all characters in the database
value must match the search string (excluding leading and
trailing blanks). Both types of string searches are case
insensitive.
NOTES:
DBMATCH is meant to be used for items which do not have duplicate values
in a database (e.g. catalog numbers). If more than one entry is found
for a particular item value, then only the first one is stored in LIST.
When linked databases are opened together, DBMATCH can only be
used to search on items in the primary database.
EXAMPLE:
Make a vector which points from entries in the Yale Bright Star catalog
to those in the Hipparcos catalog, using the HD number
IDL> dbopen, 'yale_bs' ;Open the Yale Bright star catalog
IDL> dbext, -1, 'HD', hd ;Get the HD numbers
IDL> dbopen, 'hipparcos' ;Open the Hipparcos catalog
IDL> list = dbmatch( 'HD', HD) ;Get entries in Hipparcos catalog
;corresponding to each HD number.
PROCEDURE CALLS:
DB_ITEM, DB_ITEM_INFO(), DBEXT, DBFIND_SORT()
REVISION HISTORY:
Written, W. Landsman STX February, 1990
Fixed error when list in parameter used May, 1992
Faster algorithm with sorted item when listin parameter supplied
Added keyword FULLSTRING,check for empty database, William Thompson,
GSFC, 15 March 1995
Work for more than 32767 values, added CATCH W. Landsman July 1997
Change some loop variables to type LONG, W. Landsman July 1999
Remove loop for substring searches (faster) W. landsman August 1999
Replace DATATYPE() with size(/TNAME) W. Landsman November 2001
Fixed typo when search on sorted items W. Landsman February 2002
Fixed bug from Nov 2001 where /FULLSTRING was always set. W.L Feb 2007
(See astrolib/pro/dbmatch.pro)
DBOPEN
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NAME:
DBOPEN
PURPOSE:
Routine to open an IDL database
CALLING SEQUENCE:
dbopen, name, update
INPUTS:
name - (Optional) name or names of the data base files to open.
It has one of the following forms:
'name' -open single data base file
'name1,name2,...,nameN' - open N files which are
connected via pointers.
'name,*' -Open the data base with all data
bases connected via pointers
'' -Interactively allow selection of
the data base files.
If not supplied then '' is assumed.
name may optionally be a string array with one name
per element.
update - (Optional) Integer flag specifing openning for update.
0 - Open for read only
1 - Open for update
2 - Open index file for update only
!PRIV must be 2 or greater to open a file for update.
If a file is opened for update only a single data base
can be specified.
OUTPUTS:
none
INPUT-OUTPUT KEYWORD:
UNAVAIL - If present, a "database doesn't exit" flag is returned
through it. 0 = the database exists and was opened (if
no other errors arose). 1 = the database doesn't exist.
Also if present, the error message for non-existent databases
is suppressed. The action, however, remains the same.
SIDE EFFECTS:
The .DBF and .dbx files are opened using unit numbers obtained by
GET_LUN. Descriptions of the files are placed in the common block
DB_COM.
PROCEDURES CALLED:
DBCLOSE, DB_INFO(), SELECT_W, ZPARCHECK
HISTORY:
For IDL Version 2 W. Landsman May 1990 -- Will require further
modfication once SCREEN_SELECT is working
Modified to work under Unix, D. Neill, ACC, Feb 1991.
UNAVAIL keyword added. M. Greason, Hughes STX, Feb 1993.
William Thompson, GSFC/CDS (ARC), 1 June 1994
Added support for external (IEEE) representation.
William Thompson, GSFC, 3 November 1994
Modified to allow ZDBASE to be a path string.
8/29/95 JKF/ACC - forces lowercase for input database names.
W. Landsman, Use CATCH to catch errors July, 1997
W. Landsman Use vector call to FDECOMP, STRSPLIT() Sep 2006
W. Landsman Remove obsolete keywords to OPEN Sep 2006
Replace SCREEN_SELECT with SELECT_W, remove IEEE_TO_HOST WL Jan 2009
Fix typos in BYTEORDER introduced Jan 2009 G. Scandariato/W.L.Feb. 2009
Support new DB format which allows entry lengths > 32767 bytes
W.L. October 2010
William Thompson, fixed bug opening multiple databases Dec 2010
Fix problem with external databases WL Sep 2011
(See astrolib/pro/dbopen.pro)
DBPRINT
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NAME:
DBPRINT
PURPOSE:
Procedure to print specified items from a list of database entries
CALLING SEQUENCE:
dbprint, list, [items, FORMS= , TEXTOUT= , /AdjustFormat, /NoHeader]
INPUTS:
list - list of entry numbers to be printed, vector or scalar
if list = -1, then all entries will be printed.
An error message is returned if any entry number is larger
than the number of entries in the database
OPTIONAL INPUT-OUTPUT:
items - items to be printed, specified in any of the following ways:
form 1 scalar string giving item(s) as list of names
separated by commas
form 2 string array giving list of item names
form 3 string of form '$filename' giving name
of text file containing items (one item per
line)
form 4 integer scalar giving single item number or
integer vector list of item numbers
form 5 Null string specifying interactive selection. This
is the default if 'items' is not supplied
form 6 '*' select all items, printout will be in
table format.
If items was undefined or a null string on input, then
on output it will contain the items interactively selected.
OPTIONAL INPUT KEYWORDS:
/ADJUSTFORMAT - If set, then the format length for string items will
be adjusted to the maximum length for the entries to be printed.
This option will slow down DBPRINT because it requires the
string items be extracted and their maximum length determined
prior to any printing. However, it enables the display of
string items without any truncation or wasted space.
FORMS - The number of printed lines per page. If forms is not
present, output assumed to be in PORTRAIT form, and
a heading and 47 lines are printed on each page, with
a page eject between each page. For LANDSCAPE form with
headings on each page, and a page eject between pages, set
forms = 34. For a heading only on the first page, and no
page eject, set forms = 0. This is the default for output
to the terminal.
TEXTOUT - Integer (0-7) or string used to determine output device (see
TEXTOPEN for more info). If not present, the !TEXTOUT system
variable is used.
textout=0 Nowhere
textout=1 if a TTY then TERMINAL using /more option
otherwise standard (Unit=-1) output
textout=2 if a TTY then TERMINAL without /more option
otherwise standard (Unit=-1) output
textout=3 dbprint.prt (file)
textout=4 laser.tmp
textout=5 user must open file
textout=7 same as 3 but text is appended to .prt
textout = filename (default extension of .prt)
/NOHEADER - If this keyword is set, then the column headers will not
be printed
EXAMPLE:
The following example shows how a multiple valued item DATAMAX can be
printed as separate columns. In the WFPC2 target database, DATAMAX
is an item with 4 values, one for each of the 4 chips
IDL> dbopen,'wflog'
IDL> dbprint,list,'entry,datamax(0),datamax(1),datamax(2),datamax(3)'
SYSTEM VARIABLES:
Output device controlled by non-standard system varaible !TEXTOUT, if
TEXTOUT keyword is not used.
NOTES:
Users may want to adjust the default lines_per_page value given at
the beginning of the program for their own particular printer.
PROCEDURE CALLS:
db_info(), db_item_info(), dbtitle(), dbxval(), textopen, textclose
zparcheck
HISTORY:
version 2 D. Lindler Nov. 1987 (new db format)
Test if user pressed 'Q' in response to /MORE W. Landsman Sep 1991
Apply STRTRIM to free form (table) output W. Landsman Dec 1992
Test for string value of TEXTOUT W. Landsman Feb 1994
William Thompson, GSFC, 3 November 1994
Modified to allow ZDBASE to be a path string.
W. Landsman, GSFC, July, 1997, Use CATCH to catch errors
Removed STRTRIM in table format output to handle byte values April 1999
Fixed occasional problem when /NOHEADER is supplied Sep. 1999
Only byteswap when necessary for improved performance Feb. 2000
Change loop index for table listing to type LONG W. Landsman Aug 2000
Entry vector can be any integer type W. Landsman Aug. 2001
Replace DATATYPE() with size(/TNAME) W. Landsman Nov. 2001
No page eject for TEXTOUT =5 W. Landsman Nov. 2001
No initial page eject W. Landsman Jan. 2002
Added AdjustFormat keyword W. Landsman Sep. 2002
Assume since V5.3 (STRJOIN) W. Landsman Feb. 2004
Fix display on GUI terminals W. Landsman March 2006
Remove VMS statements W. Landsman Sep 2006
Remove EXECUTE statement W. Landsman Jan 2007
Fix display of multi element items W. Landsman Aug 2010
Fix problem with linked databases W. Landsman Dec 2011
(See astrolib/pro/dbprint.pro)
DBPUT
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NAME:
DBPUT
PURPOSE:
Procedure to place a new value for a specified item into
a data base file entry.
CALLING SEQUENCE:
dbput, item, val, entry
INPUTS:
item - item name or number
val - item value(s)
INPUT/OUTPUT:
entry - entry (byte array) or scalar entry number.
if entry is a scalar entry number then the data
base file will be updated. Otherwise the change
will be only made to the entry array which must
be written latter using DBWRT.
OPERATIONAL NOTES:
If entry is a scalar entry number or the input file name
is supplied, the entry in the data base will be updated
instead of a supplied entry variable. In this case, !priv
must be greater than 1.
EXAMPLE:
IDL> dbput,'WAVELEN',1215.6,entry
PROCEDURES USED:
DB_ITEM, DBRD, DBXPUT, DBWRT
HISTORY:
version 2 D. Lindler Feb 1988 (new db formats)
modified to convert blanks into zeros correctly D. Neill Jan 1991
Converted to IDL V5.0 W. Landsman September 1997
V5.2 version support unsigned, 64bit integers W. Landsman Sep. 2001
(See astrolib/pro/dbput.pro)
DBRD
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NAME:
DBRD
PURPOSE:
procedure to read an entry from a data base file or from
linked multiple databases.
CALLING SEQUENCE:
dbrd, enum, entry, [available, dbno, /NoConvert]
INPUTS:
enum - entry number to read, integer scalar
OUTPUT:
entry - byte array containing the entry
OPTIONAL OUTPUT:
available - byte array with length equal to number of data
bases opened. available(i) eq 1 if an entry (pointed
to) is available. It always equals 1 for the first
data base, otherwise it is an error condition.
OPTIONAL INPUT:
dbno - specification of the data base number to return. If
supplied, only the record for the requested data base
number is returned in entry. Normally this input should
not be supplied. dbno is numbered for 0 to n-1 and gives
the number of the data base opened. The data bases are
numbered in the order supplied to dbopen. If dbno is supplied
then the entry number refers to that data base and not the
primary or first data base. If set to -1, then it means all
data bases opened (same as not supplying it)
OPTIONAL INPUT KEYWORD:
noconvert - if set then don't convert external to host format.
Assumes that calling program will take care of this
requirement.
OPERATIONAL NOTES:
If multiple data base files are opened, the records are
concatenated with each other
HISTORY
version 2 D. Lindler Nov. 1987
William Thompson, GSFC/CDS (ARC), 1 June 1994
Added support for external (IEEE) representation.
Version 3, Richard Schwartz, GSFC/SDAC, 23-Aug-1996
Add noconvert keyword
Converted to IDL V5.0 W. Landsman September 1997
Version 4, 2 May 2003, W. Thompson
Use BSWAP keyword to DBXVAL instead of calling IEEE_TO_HOST.
(See astrolib/pro/dbrd.pro)
DBSEARCH
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NAME:
DBSEARCH
PURPOSE:
Subroutine of DBFIND() to search a vector for specified values
CALLING SEQUENCE:
dbsearch, type, svals, values, good, [ /FULLSTRING, COUNT = ]
INPUT:
type - type of search (output from dbfparse)
svals - search values (output from dbfparse)
values - array of values to search
OUTPUT:
good - indices of good values
OPTIONAL INPUT KEYWORD:
/FULLSTRING - By default, one has a match if a search string is
included in any part of a database value (substring match).
But if /FULLSTRING is set, then all characters in the database
value must match the search string (excluding leading and
trailing blanks). Both types of string searches are case
insensitive.
OPTIONAL OUTPUT KEYWORD:
COUNT - Integer scalar giving the number of valid matches
SIDE EFFECTS:
The obsolete system variable !ERR is set to number of good values
REVISION HISTORY:
D. Lindler July,1987
Added COUNT keyword, deprecate !ERR W. Landsman March 2000
Some speed improvements W.L. August 2008
Add compound operators, slightly faster WL November 2009
(See astrolib/pro/dbsearch.pro)
DBSORT
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NAME:
DBSORT
PURPOSE:
Routine to sort list of entries in data base
CALLING SEQUENCE:
result = dbsort( list, items , [ REVERSE = ])
INPUTS:
list - list of entry numbers to sort
-1 to sort all entries
items - list of items to sort (up to 9 items)
OUTPUT:
result - numeric vector giving input list sorted by items
OPTIONAL KEYWORD INPUT:
REVERSE - scalar or vector with the same number of elements as the
the number of items to sort. If the corresponding element of REVERSE
is non-zero then that item is sorted in descending rather than
ascending order.
EXAMPLE:
Sort an astronomical catalog with RA as primary sort, and declination
as secondary sort (used when RA values are equal)
IDL> NEWLIST = DBSORT( -1, 'RA,DEC' )
If for some reason, one wanted the DEC sorted in descending order, but
the RA in ascending order
IDL> NEWLIST = DBSORT( -1, 'RA,DEC', REV = [ 0, 1 ] )
METHOD:
The list is sorted such that each item is sorted into
asscending order starting with the last item.
COMMON BLOCKS:
DBCOM
PROCEDURES USED:
ZPARCHECK, BSORT, DBEXT, DB_ITEM
HISTORY
VERSION 1 D. Lindler Oct. 86
Added REVERSE keyword W. Landsman August, 1991
Avoid use of EXECUTE() for V6.1 or later W. Landsman Dec 2006
Assume since V6.1 W. Landsman June 2009
Add TEMPORARY call W. Lnadsman July 2009
(See astrolib/pro/dbsort.pro)
DBTARGET
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NAME:
DBTARGET
PURPOSE:
Find sources in a database within specified radius of specified target
EXPLANATION:
Uses QuerySimbad to translate target name to RA and Dec, and then uses
DBCIRCLE() to find any entries within specified radius. Database must
include items named 'RA' (in hours) and 'DEC' (in degrees) and must
have previously been opened with DBOPEN
CALLING SEQUENCE:
list = DBTARGET(target, [radius, sublist, /SILENT, DIS= ,/TO_B1950 ] )
INPUTS:
TARGET - A scalar string giving an astronomical target name, which
will be translated into J2000 celestial coordinates by QuerySimbad
OPTIONAL INPUT:
RADIUS - Radius of the search field in arc minutes, scalar.
Default is 5 arc minutes
SUBLIST - Vector giving entry numbers in currently opened database
to be searched. Default is to search all entries
OUTPUTS:
LIST - Vector giving entry numbers in the currently opened catalog
which have positions within the specified search circle
LIST is set to -1 if no sources fall within the search circle
!ERR is set to the number sources found.
OPTIONAL OUTPUT
DIS - The distance in arcminutes of each entry specified by LIST
to the search center specified by the target.
OPTIONAL KEYWORD INPUT:
/SILENT - If this keyword is set, then DBTARGET will not print the
number of entries found at the terminal
/TO_B1950 - If this keyword is set, then the SIMBAD J2000 coordinates
are converted to B1950 before searching the database
NOTE: The user must determine on his own whether the database
is in B1950 or J2000 coordinates.
RESTRICTIONS;
The database must have items 'RA' (in hours) and 'DEC' (in degrees).
Alternatively, the database could have items RA_OBJ and DEC_OBJ
(both in degrees)
EXAMPLE:
(1) Use the HST_CATALOG database to find all HST observations within
5' (the default) of M33
IDL> dbopen,'hst_catalog'
IDL> list = dbtarget('M33')
(2) As above but restrict targets within 2' of the nucleus using the
WFPC2 camara
IDL> dbopen,'hst_catalog'
IDL> sublist = dbfind('config=WFPC2')
IDL> list = dbtarget('M33',2,sublist)
PROCEDURE CALLS:
QuerySimbad, DBCIRCLE()
REVISION HISTORY:
Written W. Landsman SSAI September 2002
Propagate /SILENT keyword to QuerySimbad W. Landsman Oct 2009
Make sure a database is open W.L. Oct 2010
(See astrolib/pro/dbtarget.pro)
DBTITLE
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NAME:
DBTITLE
PURPOSE:
function to create title line for routine dbprint
CALLING SEQUENCE:
result = dbtitle( c, f )
INPUTS:
c = string array of titles for each item
f = field length of each item
OUTPUT:
header string returned as function value
OPERATIONAL NOTES:
this is a subroutine of DBPRINT.
HISTORY:
version 1 D. Lindler Sept 86
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/dbtitle.pro)
DBUPDATE
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NAME:
DBUPDATE
PURPOSE:
Update columns of data in a database -- inverse of DBEXT
EXPLANATION:
Database must be open for update before calling DBUPDATE
CALLING SEQUENCE:
dbupdate, list, items, v1, [ v2, v3, v4......v14 ]
INPUTS:
list - entries in database to be updated, scalar or vector
If list=-1 then all entries will be updated
items -standard list of items that will be updated.
v1,v2....v14 - vectors containing values for specified items. The
number of vectors supplied must equal the number of items
specified. The number of elements in each vector should be
the same.
OPTIONAL KEYWORD INPUT:
/NOINDEX - If set, then DBUPDATE will not update the index file. This
keyword is useful to save if additional updates will occur,
and the index file need only be updated on the last call.
EXAMPLES:
A database STAR contains RA and DEC in radians, convert to degrees
IDL> !PRIV=2 & dbopen,'STAR',1 ;Open database for update
IDL> dbext,-1,'RA,DEC',ra,dec ;Extract RA and DEC, all entries
IDL> ra = ra*!RADEG & dec=dec*!RADEG ;Convert to degrees
IDL> dbupdate,-1,'RA,DEC',ra,dec ;Update database with new values
NOTES:
It is quicker to update several items simultaneously rather than use
repeated calls to DBUPDATE.
It is possible to update multiple valued items. In this case, the
input vector should be of dimension (NVAL,NLIST) where NVAL is the
number of values per item, and NLIST is the number of entries to be
updated. This vector will be temporarily transposed by DBUPDATE but
will be restored before DBUPDATE exits.
REVISION HISTORY
Written W. Landsman STX March, 1989
Work for multiple valued items May, 1991
String arrays no longer need to be fixed length December 1992
Transpose multiple array items back on output December 1993
Faster update of external databases on big endian machines November 1997
Converted to IDL V5.0 W. Landsman 24-Nov-1997
Added /NOINDEX keyword W. Landsman July 2001
(See astrolib/pro/dbupdate.pro)
DBVAL
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NAME:
DBVAL
PURPOSE:
procedure to extract value(s) of the specified item from
a data base file entry.
CALLING SEQUENCE:
result = dbval( entry, item )
INPUTS:
entry - byte array containing the entry, or a scalar entry number
item - name (string) or number (integer) of the item
OUTPUT:
the value(s) will be returned as the function value
EXAMPLE:
Extract a flux vector from entry 28 of the database FARUV
==> flux = dbval(28,'FLUX')
HISTORY:
version 2 D. Lindler Nov, 1987 (new db format)
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/dbval.pro)
DBWRT
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NAME:
DBWRT
PURPOSE:
procedure to update or add a new entry to a data base
CALLING SEQUENCE:
dbwrt, entry, [ index, append, /NoConvert ]
INPUTS:
entry - entry record to be updated or added if first
item (entry number=0)
OPTIONAL INPUTS:
index - optional integer flag, if set to non zero then index
file is updated. (default=0, do not update index file)
(Updating the index file is time-consuming, and should
normally be done after all changes have been made.
append - optional integer flag, if set to non-zero the record
is appended as a new entry, regardless of what the
entry number in the record is. The entry number will
be reset to the next entry number in the file.
OUTPUTS:
data base file is updated.
If index is non-zero then the index file is updated.
OPTIONAL INPUT KEYWORD:
NoConvert - If set then don't convert to host format with an external
database. Useful when the calling program decides that
conversion isn't needed (i.e. on a big-endian machine), or
takes care of the conversion itself.
OPERATIONAL NOTES:
!PRIV must be greater than 1 to execute
HISTORY:
version 2 D. Lindler Feb. 1988 (new db format)
converted to IDL Version 2. M. Greason, STX, June 1990.
William Thompson, GSFC/CDS (ARC), 28 May 1994
Added support for external (IEEE) representation.
Faster handling of byte swapping W. L. August 2010
(See astrolib/pro/dbwrt.pro)
DBXPUT
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NAME:
DBXPUT
PURPOSE:
routine to replace value of an item in a data base entry
CALLING SEQUENCE:
dbxput, val, entry, idltype, sbyte, nbytes
INPUT:
val - value(s) to be placed into entry, string values might be
truncated to fit number of allowed bytes in item
entry - entry or entries to be updated
idltype - idl data type for item (1-7)
sbyte - starting byte in record
nbytes - total number of bytes in value added
OUTPUT:
entry - (updated)
OPERATIONAL NOTES:
This routine assumes that the calling procedure or user knows what he
or she is doing. String items are truncated or padded to the fixed
size specified by the database but otherwise no validity checks are
made.
HISTORY:
version 1, D. Lindler Aug, 1986
converted to IDL Version 2. M. Greason, STX, June 1990.
Work with multiple element string items W. Landsman August 1995
Really work with multiple element string items
R. Bergman/W. Landsman July 1996
Work with multiple entries, R. Schwartz, GSFC/SDAC August 1996
Use /overwrite with REFORM() W. Landsman May 1997
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/dbxput.pro)
DBXVAL
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NAME:
DBXVAL
PURPOSE:
Quickly return a value of the specified item number
EXPLANATION:
Procedure to quickly return a value of the specified item number
from the entry.
CALLING SEQUENCE:
result = dbxval( entry, idltype, nvalues, sbyte, nbytes )
INPUTS
entry - entry or entries from data base (bytarr)
idltype - idl data type (obtained with db_item_info)
nvalues - number of values to return (obtained with db_item)
sbyte - starting byte in the entry (obtained with db_item)
nbytes - number of bytes (needed only for string type)
(obtained with db_item)
OUTPUTS:
function value is value of the specified item in entry
KEYWORDS:
bswap - If set, then IEEE_TO_HOST is called.
RESTRICTIONS:
To increase speed the routine assumes that entry and item are
valid and that the data base is already opened using dbopen.
REVISION HISTORY:
version 0 D. Lindler Nov. 1987 (for new db format)
Version 1, William Thompson, GSFC, 28 March 1994.
Incorporated into CDS library.
Version 2, Richard Schwartz, GSFC/SDAC, 23 August 1996
Allowed Entry to have 2 dimensions
Version 2.1, 22 Feb 1997, JK Feggans,
avoid reform for strings arrays.
Version 2.2 Use overwrite with REFORM(), W. Landsman, May 1997
Converted to IDL V5.0 W. Landsman September 1997
Work for multiple-valued strings W. Landsman October 2000
Add new 64bit & unsigned integer datatypes W.Landsman July 2001
Version 3, 2-May-2003, JK Feggans/Sigma, W.T. Thompson
Added BSWAP keyword to avoid floating errors on some platforms.
(See astrolib/pro/dbxval.pro)
DB_ENT2EXT
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NAME:
DB_ENT2EXT
PURPOSE:
Convert a database entry to external (IEEE) data format
EXPLANATION:
Converts a database entry to external (IEEE) data format prior to
writing it. Called from DBWRT.
CALLING SEQUENCE:
DB_ENT2EXT, ENTRY
INPUTS:
ENTRY = Byte array containing a single record to be written to the
database file.
OUTPUTS:
ENTRY = The converted array is returned in place of the input array.
COMMON BLOCKS:
DB_COM
HISTORY:
Version 1, William Thompson, GSFC/CDS (ARC), 1 June 1994
Version 2, William Thompson, GSFC/CDS (ARC), 15 September 1995
Fixed bug where only the first element in a
multidimensional array was converted.
Version 2.1 W. Landsman August 2010 Fix for multidimensional strings
Version 2.2 W. Landsman Sep 2011 Work with new DB format
(See astrolib/pro/db_ent2ext.pro)
DB_ENT2HOST
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NAME:
DB_ENT2HOST
PURPOSE:
Converts a database entry from external data format to host format.
EXPLANATION:
All items are extracted from the entry, and then converted to host
format, and placed back into the entry. Called from DBRD and DBEXT_DBF.
CALLING SEQUENCE:
DB_ENT2HOST, ENTRY, DBNO
INPUTS:
ENTRY = Byte array containing a single record read from the
database file.
DBNO = Number of the opened database file.
OUTPUTS:
ENTRY = The converted array is returned in place of the input array.
COMMON BLOCKS:
DB_COM
HISTORY:
Version 1, William Thompson, GSFC/CDS (ARC), 1 June 1994
Version 2, William Thompson, GSFC/CDS (ARC), 15 September 1995
Fixed bug where only the first element in a
multidimensional array was converted.
Version 3, Richard Schwartz, GSFC/SDAC, 23 August 1996
Allow 2 dimensional byte arrays for entries to facilitate
multiple entry processing. Pass IDLTYPE onto IEEE_TO_HOST
Version 4, 2 May 2003, W. Thompson
Use BSWAP keyword to DBXVAL instead of calling IEEE_TO_HOST.
Version 4.1 W. Landsman August 2010 Fix for multidimensional strings
Version 4.2 W. Landsman Sep 2011 Work with new DB format
(See astrolib/pro/db_ent2host.pro)
DB_INFO
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NAME:
DB_INFO
PURPOSE:
Function to obtain information on opened data base file(s)
CALLING SEQUENCES:
1) result = db_info(request)
2) result = db_info(request,dbname)
INPUTS (calling sequence 1):
request - string specifying requested value(s)
value of request value returned in result
'open' Flag set to 1 if data base(s) are opened
'number' Number of data base files opened
'items' Total number of items (all db's opened)
'update' update flag (1 if opened for update)
'unit_dbf' Unit number of the .dbf files
'unit_dbx' Unit number of the .dbx files
'entries' Number of entries in the db's
'length' Record lengths for the db's
'external' True if the db's are in external format
INPUTS (calling sequence 2):
request - string specifying requested value(s)
value of request value returned in result
'name' Name of the data base
'number' Sequential number of the db
'items' Number of items for this db
'item1' Position of item1 for this db
in item list for all db's
'item2' Position of last item for this db.
'pointer' Number of the item which points
to this db. 0 for first or primary
db. -1 if link file pointers.
'length' Record length for this db.
'title' Title of the data base
'unit_dbf' Unit number of the .dbf file
'unit_dbx' Unit number of the .dbx file
'entries' Number of entries in the db
'seqnum' Last sequence number used
'alloc' Allocated space (# entries)
'update' 1 if data base opened for update
'external' True if data base in external format
'newdb' True if new (post Oct 2010) format
that allows entries > 32767 bytes
dbname - data base name or number
OUTPUTS:
Requested value(s) are returned as the function value.
HISTORY:
version 1 D. Lindler Oct. 1987
changed type from 1 to 7 for IDLV2, J. Isensee, Nov., 1990
William Thompson, GSFC/CDS (ARC), 30 May 1994
Added EXTERNAL request type.
Support new DB format, add NEWDB request type W. Landsman Oct 2010
(See astrolib/pro/db_info.pro)
DB_ITEM
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NAME:
DB_ITEM
PURPOSE:
Returns the item numbers and other info. for an item name.
EXPLANATION:
Procedure to return the item numbers and other information
of a specified item name
CALLING SEQUENCE:
db_item, items, itnum, ivalnum, idltype, sbyte, numvals, nbytes
INPUTS:
items - item name or number
form 1 scalar string giving item(s) as list of names
separated by commas
form 2 string array giving list of item names
form 3 string of form '$filename' giving name
of text file containing items (one item per
line)
form 4 integer scalar giving single item number or
integer vector list of item numbers
form 5 Null string specifying interactive selection
Upon return items will contain selected items
in form 1
form 6 '*' select all items
OUTPUTS:
itnum - item number
ivalnum - value(s) number from multiple valued item
idltype - data type(s) (1=string,2=byte,4=i*4,...)
sbyte - starting byte(s) in entry
numvals - number of data values for item(s)
It is the full length of a vector item unless
a subscript was supplied
nbytes - number of bytes for each value
All outputs are vectors even if a single item is requested
OPTIONAL INPUT KEYWORDS:
ERRMSG = If defined and passed, then any error messages will
be returned to the user in this parameter rather than depending
on the MESSAGE routine in IDL. If no errors are encountered,
then a null string is returned. In order to use this feature,
ERRMSG must be defined first, e.g.
ERRMSG = ''
DB_ITEM, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
PROCEDURE CALLS:
DB_INFO, GETTOK, SELECT_W
REVISION HISTORY:
Written: D. Lindler, GSFC/HRS, October 1987
Version 2, William Thompson, GSFC, 17-Mar-1997
Added keyword ERRMSG
Use STRSPLIT instead of GETTOK to parse form 1, W. Landsman July 2002
Assume since V5.4 use FILE_EXPAND_PATH() instead of SPEC_DIR()
W. Landsman April 2006
Support new DB format allowing entry lengths > 32767 bytes WL Oct 2010
Ignore blank lines in .items file WL February 2011
(See astrolib/pro/db_item.pro)
DB_ITEM_INFO
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NAME:
DB_ITEM_INFO
PURPOSE:
routine to return information on selected item(s) in the opened
data bases.
CALLING SEQUENCE:
result = db_item_info( request, itnums)
INPUTS:
request - string giving the requested information.
'name' - item names
'idltype' - IDL data type (integers)
see documentation of intrinsic SIZE funtion
'nvalues' - vector item length (1 for scalar)
'sbyte' - starting byte in .dbf record (use bytepos
to get starting byte in record returned by
dbrd)
'nbytes' - bytes per data value
'index' - index types
'description' - description of the item
'pflag' - pointer item flags
'pointer' - data bases the items point to
'format' - print formats
'flen' - print field length
'headers' - print headers
'bytepos' - starting byte in dbrd record for the items
'dbnumber' - number of the opened data base
'pnumber' - number of db it points to (if the db is
opened)
'itemnumber' - item number in the file
itnums -(optional) Item numbers. If not supplied info on all items
are returned.
OUTPUT:
Requested information is returned as a vector. Its type depends
on the item requested.
HISTORY:
version 1 D. Lindler Nov. 1987
Converted to IDL V5.0 W. Landsman September 1997
Support new DB format which allows > 32767 bytes W.L. Oct 2010
(See astrolib/pro/db_item_info.pro)
DB_OR
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NAME:
DB_OR
PURPOSE:
Combine two vectors of entry numbers, removing duplicate values.
EXPLANATION:
DB_OR can also be used to remove duplicate values from any longword
vector
CALLING SEQUENCE:
LIST = DB_OR( LIST1 ) ;Remove duplicate values from LIST1
or
LIST = DB_OR( LIST1, LIST2 ) ;Concatenate LIST1 and LIST2, remove dups
INPUTS:
LIST1, LIST2 - Vectors containing entry numbers, must be non-negative
integers or longwords.
OUTPUT:
LIST - Vector containing entry numbers in either LIST1 or LIST2
METHOD
DB_OR returns where the histogram of the entry vectors is non-zero
PROCEDURE CALLS
ZPARCHECK - checks parameters
REVISION HISTORY:
Written, W. Landsman February, 1989
Check for degenerate values W.L. February, 1993
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/db_or.pro)
DB_TITLES
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NAME:
DB_TITLES
PURPOSE:
Print database name and title. Called by DBHELP
CALLING SEQUENCE:
db_titles, fnames, titles
INPUT:
fnames - string array of data base names
SIDE EFFECT:
Database name is printed along with the description in the .dbh file
HISTORY:
version 2 W. Landsman May, 1989
modified to work under Unix, D. Neill, ACC, Feb 1991.
William Thompson, GSFC/CDS (ARC), 1 June 1994
Added support for external (IEEE) representation.
William Thompson, GSFC, 3 November 1994
Modified to allow ZDBASE to be a path string.
Converted to IDL V5.0 W. Landsman September 1997
Assume since V5.5, W. Landsman September 2006
(See astrolib/pro/db_titles.pro)
DELVARX
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NAME:
DELVARX
PURPOSE:
Delete up to 10 variables for memory management (can call from routines)
EXPLANATION:
Like intrinsic DELVAR function, but can be used from any calling level
Modified in January 2012 to always free memory associated with
pointers/objects and remove the use of EXECUTE()
Also look at
CALLING SEQUENCE:
DELVARX, p0, [p1, p2......p9]
INPUTS:
p0, p1...p9 - variables to delete
OBSOLETE KEYWORD:
/FREE_MEM - formerly freed memory associated with pointers
and objects. Since this is now the DELVARX default this
keyword does nothing.
METHOD:
Uses HEAP_FREE and PTR_NEW(/NO_COPY) to delete variables and free
memory
REVISION HISTORY:
Copied from the Solar library, written by slf, 25-Feb-1993
Added to Astronomy Library, September 1995
Modified, 26-Mar-2003, Zarro (EER/GSFC) 26-Mar-2003
- added FREE_MEM to free pointer/objects
Modified, 28-Jan-2012, E. Rykoff (SLAC), W. Landsman -
replace EXECUTE calls with SCOPE_VARFETCH.
(See astrolib/pro/delvarx.pro)
DEREDD
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NAME:
DEREDD
PURPOSE:
Deredden stellar Stromgren parameters given for a value of E(b-y)
EXPLANATION:
See the procedure UVBYBETA for more info.
CALLING SEQUENCE:
deredd, eby, by, m1, c1, ub, by0, m0, c0, ub0, /UPDATE
INPUTS:
Eby - color index E(b-y),scalar (E(b-y) = 0.73*E(B-V) )
by - b-y color (observed)
m1 - Stromgren line blanketing parameter (observed)
c1 - Stromgren Balmer discontinuity parameter (observed)
ub - u-b color (observed)
These input values are unaltered unless the /UPDATE keyword is set
OUTPUTS:
by0 - b-y color (dereddened)
m0 - Line blanketing index (dereddened)
c0 - Balmer discontinuity parameter (dereddened)
ub0 - u-b color (dereddened)
OPTIONAL INPUT KEYWORDS:
/UPDATE - If set, then input parameters are updated with the dereddened
values (and output parameters are not used).
REVISION HISTORY:
Adapted from FORTRAN routine DEREDD by T.T. Moon
W. Landsman STX Co. April, 1988
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/deredd.pro)
DETABIFY
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NAME:
DETABIFY
PURPOSE:
Replaces tabs in character strings with appropriate number of spaces
EXPLANATION:
The number of space characters inserted is calculated to space
out to the next effective tab stop, each of which is eight characters
apart.
CALLING SEQUENCE:
Result = DETABIFY( CHAR_STR )
INPUT PARAMETERS:
CHAR_STR = Character string variable (or array) to remove tabs from.
OUTPUT:
Result of function is CHAR_STR with tabs replaced by spaces.
RESTRICTIONS:
CHAR_STR must be a character string variable.
MODIFICATION HISTORY:
William Thompson, Feb. 1992.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/detabify.pro)
DIST_CIRCLE
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NAME:
DIST_CIRCLE
PURPOSE:
Form a square array where each value is its distance to a given center.
EXPLANATION:
Returns a square array in which the value of each element is its
distance to a specified center. Useful for circular aperture photometry.
CALLING SEQUENCE:
DIST_CIRCLE, IM, N, [ XCEN, YCEN, /DOUBLE ]
INPUTS:
N = either a scalar specifying the size of the N x N square output
array, or a 2 element vector specifying the size of the
N x M rectangular output array.
OPTIONAL INPUTS:
XCEN,YCEN = Scalars designating the X,Y pixel center. These need
not be integers, and need not be located within the
output image. If not supplied then the center of the output
image is used (XCEN = YCEN = (N-1)/2.).
OUTPUTS:
IM - N by N (or M x N) floating array in which the value of each
pixel is equal to its distance to XCEN,YCEN
OPTIONAL INPUT KEYWORD:
/DOUBLE - If this keyword is set and nonzero, the output array will
be of type DOUBLE rather than floating point.
EXAMPLE:
Total the flux in a circular aperture within 3' of a specified RA
and DEC on an 512 x 512 image IM, with a header H.
IDL> adxy, H, RA, DEC, x, y ;Convert RA and DEC to X,Y
IDL> getrot, H, rot, cdelt ;CDELT gives plate scale deg/pixel
IDL> cdelt = cdelt*3600. ;Convert to arc sec/pixel
IDL> dist_circle, circle, 512, x, y ;Create a distance circle image
IDL> circle = circle*abs(cdelt[0]) ;Distances now given in arcseconds
IDL> good = where(circle LT 180) ;Within 3 arc minutes
IDL> print,total( IM[good] ) ;Total pixel values within 3'
RESTRICTIONS:
The speed of DIST_CIRCLE decreases and the the demands on virtual
increase as the square of the output dimensions. Users should
dimension the output array as small as possible, and re-use the
array rather than re-calling DIST_CIRCLE
MODIFICATION HISTORY:
Adapted from DIST W. Landsman March 1991
Allow a rectangular output array W. Landsman June 1994
Converted to IDL V5.0 W. Landsman September 1997
Add /DOUBLE keyword, make XCEN,YCEN optional W. Landsman Jun 1998
(See astrolib/pro/dist_circle.pro)
DIST_ELLIPSE
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NAME:
DIST_ELLIPSE
PURPOSE:
Create a mask array useful for elliptical aperture photemetry
EXPLANATION:
Form an array in which the value of each element is equal to the
semi-major axis of the ellipse of specified center, axial ratio, and
position angle, which passes through that element. Useful for
elliptical aperture photometry.
CALLING SEQUENCE:
DIST_ELLIPSE, IM, N, XC, YC, RATIO, POS_ANG, /DOUBLE
INPUTS:
N = either a scalar specifying the size of the N x N square output
array, or a 2 element vector specifying the size of the
M x N rectangular output array.
XC,YC - Scalars giving the position of the ellipse center. This does
not necessarily have to be within the image
RATIO - Scalar giving the ratio of the major to minor axis. This
should be greater than 1 for postion angle to have its
standard meaning.
OPTIONAL INPUTS:
POS_ANG - Position angle of the major axis, measured counter-clockwise
from the Y axis. For an image in standard orientation
(North up, East left) this is the astronomical position angle.
OPTIONAL INPUT KEYWORD:
/DOUBLE - If this keyword is set and nonzero, the output array will
be of type DOUBLE rather than floating point.
OUTPUT:
IM - REAL*4 elliptical mask array, of size M x N. THe value of each
pixel is equal to the semi-major axis of the ellipse of center
XC,YC, axial ratio RATIO, and position angle POS_ANG, which
passes through the pixel.
EXAMPLE:
Total the flux in a elliptical aperture with a major axis of 3', an
axial ratio of 2.3, and a position angle of 25 degrees centered on
a specified RA and DEC. The image array, IM is 200 x 200, and has
an associated FITS header H.
ADXY, H, ra, dec, x, y ;Get X and Y corresponding to RA and Dec
GETROT, H, rot, cdelt ;CDELT gives plate scale degrees/pixel
cdelt = abs( cdelt)*3600. ;CDELT now in arc seconds/pixel
DIST_ELLIPSE, ell, 200, x, y, 2.3, 25 ;Create a elliptical image mask
ell = ell*cdelt(0) ;Distances now given in arcseconds
good = where( ell lt 180 ) ;Within 3 arc minutes
print,total( im(good) ) ;Total pixel values within 3'
RESTRICTIONS:
The speed of DIST_ELLIPSE decreases and the the demands on virtual
increase as the square of the output dimensions. Users should
dimension the output array as small as possible, and re-use the
array rather than re-calling DIST_ELLIPSE
REVISION HISTORY:
Written W. Landsman April, 1991
Somewhat faster algorithm August, 1992
Allow rectangular output array June, 1994
Converted to IDL V5.0 W. Landsman September 1997
Added /DOUBLE keyword W. Landsman July 2000
(See astrolib/pro/dist_ellipse.pro)
ECI2GEO
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NAME:
ECI2GEO
PURPOSE:
Convert Earth-centered inertial coordinates to geographic spherical coords
EXPLANATION:
Converts from ECI (Earth-Centered Inertial) (X,Y,Z) rectangular
coordinates to geographic spherical coordinates (latitude, longitude,
altitude). JD time is also needed as input.
ECI coordinates are in km from Earth center.
Geographic coordinates are in degrees/degrees/km
Geographic coordinates assume the Earth is a perfect sphere, with radius
equal to its equatorial radius.
CALLING SEQUENCE:
gcoord=eci2geo(ECI_XYZ,JDtime)
INPUT:
ECI_XYZ : the ECI [X,Y,Z] coordinates (in km), can be an array [3,n]
of n such coordinates.
JDtime: the Julian Day time, double precision. Can be a 1-D array of n
such times.
KEYWORD INPUTS:
None
OUTPUT:
a 3-element array of geographic [latitude,longitude,altitude], or an
array [3,n] of n such coordinates, double precision
COMMON BLOCKS:
None
PROCEDURES USED:
CT2LST - Convert Local Civil Time to Local Mean Sidereal Time
EXAMPLE:
IDL> gcoord=eci2geo([6378.137+600,0,0], 2452343.38982663D)
IDL> print,gcoord
0.0000000 232.27096 600.00000
(The above is the geographic direction of the vernal point on
2002/03/09 21:21:21.021, in geographic coordinates. The chosen
altitude was 600 km.)
gcoord can be further transformed into geodetic coordinates (using
geo2geodetic.pro) or into geomagnetic coordinates (using geo2mag.pro)
MODIFICATION HISTORY:
Written by Pascal Saint-Hilaire ([email protected]) on
2001/05/13
Modified on 2002/05/13, PSH : vectorization + use of JD times
(See astrolib/pro/eci2geo.pro)
EQ2HOR
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NAME:
EQ2HOR
PURPOSE:
Convert celestial (ra-dec) coords to local horizon coords (alt-az).
CALLING SEQUENCE:
eq2hor, ra, dec, jd, alt, az, [ha, LAT= , LON= , /WS, OBSNAME= , $
/B1950 , PRECESS_= 0, NUTATE_= 0, REFRACT_= 0, $
ABERRATION_= 0, ALTITUDE= , /VERBOSE, _EXTRA= ]
DESCRIPTION:
This code calculates horizon (alt,az) coordinates from equatorial
(ra,dec) coords. It is typically accurate to about 1 arcsecond or better (I
have checked the output against the publicly available XEPHEM software). It
performs precession, nutation, aberration, and refraction corrections. The
perhaps best thing about it is that it can take arrays as inputs, in all
variables and keywords EXCEPT Lat, lon, and Altitude (the code assumes these
aren't changing), and uses vector arithmetic in every calculation except
when calculating the precession matrices.
INPUT VARIABLES:
RA : Right Ascension of object (J2000) in degrees (FK5); scalar or
vector.
Dec : Declination of object (J2000) in degrees (FK5), scalar or vector.
JD : Julian Date [scalar or vector]
Note: if RA and DEC are arrays, then alt and az will also be arrays.
If RA and DEC are arrays, JD may be a scalar OR an array of the
same dimensionality.
OPTIONAL INPUT KEYWORDS:
lat : north geodetic latitude of location in degrees
lon : EAST longitude of location in degrees (Specify west longitude
with a negative sign.)
/WS : Set this to get the azimuth measured westward from south (not
East of North).
obsname: Set this to a valid observatory name to be used by the
astrolib OBSERVATORY procedure, which will return the latitude
and longitude to be used by this program.
/B1950 : Set this if your ra and dec are specified in B1950, FK4
coordinates (instead of J2000, FK5)
precess_ : Set this to 1 to force precession [default], 0 for no
precession correction
nutate_ : Set this to 1 to force nutation [default], 0 for no nutation.
aberration_ : Set this to 1 to force aberration correction [default],
0 for no correction.
refract_ : Set to 1 to force refraction correction [default], 0 for no
correction.
altitude: The altitude of the observing location, in meters. [default=0].
verbose: Set this for verbose output. The default is verbose=0.
_extra: This is for setting TEMPERATURE or PRESSURE explicitly, which are
used by CO_REFRACT to calculate the refraction effect of the
atmosphere. If you don't set these, the program will make an
intelligent guess as to what they are (taking into account your
altitude). See CO_REFRACT for more details.
OUTPUT VARIABLES: (all double precision)
alt : altitude (in degrees)
az : azimuth angle (in degrees, measured EAST from NORTH, but see
keyword WS above.)
ha : hour angle (in degrees) (optional)
DEPENDENCIES:
NUTATE, PRECESS, OBSERVATORY, SUNPOS, ADSTRING()
CO_NUTATE, CO_ABERRATION, CO_REFRACT, ALTAZ2HADEC, SETDEFAULTVALUE
BASIC STEPS
Apply refraction correction to find apparent Alt.
Calculate Local Mean Sidereal Time
Calculate Local Apparent Sidereal Time
Do Spherical Trig to find apparent hour angle, declination.
Calculate Right Ascension from hour angle and local sidereal time.
Nutation Correction to Ra-Dec
Aberration correction to Ra-Dec
Precess Ra-Dec to current equinox.
CORRECTIONS I DO NOT MAKE:
* Deflection of Light by the sun due to GR. (typically milliarcseconds,
can be arseconds within one degree of the sun)
* The Effect of Annual Parallax (typically < 1 arcsecond)
* and more (see below)
TO DO
* Better Refraction Correction. Need to put in wavelength dependence,
and integrate through the atmosphere.
* Topocentric Parallax Correction (will take into account elevation of
the observatory)
* Proper Motion (but this will require crazy lookup tables or something).
* Difference between UTC and UT1 in determining LAST -- is this
important?
* Effect of Annual Parallax (is this the same as topocentric Parallax?)
* Polar Motion
* Better connection to Julian Date Calculator.
EXAMPLE
Find the position of the open cluster NGC 2264 at the Effelsburg Radio
Telescope in Germany, on June 11, 2023, at local time 22:00 (METDST).
The inputs will then be:
Julian Date = 2460107.250
Latitude = 50d 31m 36s
Longitude = 06h 51m 18s
Altitude = 369 meters
RA (J2000) = 06h 40m 58.2s
Dec(J2000) = 09d 53m 44.0s
IDL> eq2hor, ten(6,40,58.2)*15., ten(9,53,44), 2460107.250d, alt, az, $
lat=ten(50,31,36), lon=ten(6,51,18), altitude=369.0, /verb, $
pres=980.0, temp=283.0
The program produces this output (because the VERBOSE keyword was set)
Latitude = +50 31 36.0 Longitude = +06 51 18.0
Julian Date = 2460107.250000
Ra, Dec: 06 40 58.2 +09 53 44.0 (J2000)
Ra, Dec: 06 42 15.7 +09 52 19.2 (J2023.4422)
Ra, Dec: 06 42 13.8 +09 52 26.9 (fully corrected)
LMST = +11 46 42.0
LAST = +11 46 41.4
Hour Angle = +05 04 27.6 (hh:mm:ss)
Az, El = 17 42 25.6 +16 25 10.3 (Apparent Coords)
Az, El = 17 42 25.6 +16 28 22.8 (Observer Coords)
Compare this with the result from XEPHEM:
Az, El = 17h 42m 25.6s +16d 28m 21s
This 1.8 arcsecond discrepancy in elevation arises primarily from slight
differences in the way I calculate the refraction correction from XEPHEM, and
is pretty typical.
AUTHOR:
Chris O'Dell
Univ. of Wisconsin-Madison
Observational Cosmology Laboratory
Email: [email protected]
Revision History:
August 2012 Use Strict_Extra to flag spurious keywords W. Landsman
(See astrolib/pro/eq2hor.pro)
EQPOLE
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NAME:
EQPOLE
PURPOSE:
Convert RA and Dec to X,Y using an equal-area polar projection.
EXPLANATION:
The output X and Y coordinates are scaled to be between
-90 and +90 to go from equator to pole to equator. Output map points
can be centered on the north pole or south pole.
CALLING SEQUENCE:
EQPOLE, L, B, X, Y, [ /SOUTHPOLE ]
INPUTS:
L - longitude - scalar or vector, in degrees
B - latitude - same number of elements as RA, in degrees
OUTPUTS:
X - X coordinate, same number of elements as RA. X is normalized to
be between -90 and 90.
Y - Y coordinate, same number of elements as DEC. Y is normalized to
be between -90 and 90.
KEYWORDS:
/SOUTHPOLE - Keyword to indicate that the plot is to be centered
on the south pole instead of the north pole.
REVISION HISTORY:
J. Bloch LANL, SST-9 1.1 5/16/91
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/eqpole.pro)
EQPOLE_GRID
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NAME:
EQPOLE_GRID
PURPOSE:
Produce an equal area polar projection grid overlay
EXPLANATION:
Grid is written on the current graphics device using the equal area
polar projection. EQPOLE_GRID assumes that the output plot
coordinates span the x and y ranges of -90 to 90 for a region that
covers the equator to the chosen pole. The grid is assumed to go from
the equator to the chosen pole.
CALLING SEQUENCE:
EQPOLE_GRID[,DLONG,DLAT,[/SOUTHPOLE, LABEL = , /NEW, _EXTRA=]
INPUTS:
DLONG = Optional input longitude line spacing in degrees. If left
out, defaults to 30.
DLAT = Optional input lattitude line spacing in degrees. If left
out, defaults to 30.
INPUT KEYWORDS:
/SOUTHPOLE = Optional flag indicating that the output plot is
to be centered on the south rather than the north
pole.
LABEL = Optional flag for creating labels on the output
grid on the prime meridian and the equator for
lattitude and longitude lines. If set =2, then
the longitude lines are labeled in hours and minutes.
CHARSIZE = If /LABEL is set, then CHARSIZE specifies the size
of the label characters (passed to XYOUTS)
CHARTHICK = If /LABEL is set, then CHARTHICK specifies the
thickness of the label characters (passed to XYOUTS)
/NEW = If this keyword is set, then EQPOLE_GRID will create
a new plot, rather than overlay an existing plot.
Any valid keyword to OPLOT such as COLOR, LINESTYLE, THICK can be
passed to AITOFF_GRID (though the _EXTRA facility) to to specify the
color, style, or thickness of the grid lines.
OUTPUTS:
Draws grid lines on current graphics device.
EXAMPLE:
Create a labeled equal area projection grid of the Galaxy, centered on
the South pole, and overlay stars at specified Galactic longitudes,
glong and latitudes, glat
IDL> eqpole_grid,/label,/new,/south ;Create labeled grid
IDL> eqpole, glong, glat, x,y ;Convert to X,Y coordinates
IDL> plots,x,y,psym=2 ;Overplot "star" positions.
COPYRIGHT NOTICE:
Copyright 1992, The Regents of the University of California. This
software was produced under U.S. Government contract (W-7405-ENG-36)
by Los Alamos National Laboratory, which is operated by the
University of California for the U.S. Department of Energy.
The U.S. Government is licensed to use, reproduce, and distribute
this software. Neither the Government nor the University makes
any warranty, express or implied, or assumes any liability or
responsibility for the use of this software.
AUTHOR AND MODIFICATIONS:
J. Bloch 1.4 10/28/92
Converted to IDL V5.0 W. Landsman September 1997
Create default plotting coords, if needed W. Landsman August 2000
Added _EXTRA, CHARTHICK, CHARSIZE keywords W. Landsman March 2001
(See astrolib/pro/eqpole_grid.pro)
EULER
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NAME:
EULER
PURPOSE:
Transform between Galactic, celestial, and ecliptic coordinates.
EXPLANATION:
Use the procedure ASTRO to use this routine interactively
CALLING SEQUENCE:
EULER, AI, BI, AO, BO, [ SELECT, /FK4, /RADIAN, SELECT = ]
INPUTS:
AI - Input Longitude, scalar or vector. In DEGREES unless /RADIAN
is set. If only two parameters are supplied, then AI and BI
will be modified to contain the output longitude and latitude.
BI - Input Latitude in DEGREES
OPTIONAL INPUT:
SELECT - Integer (1-6) specifying type of coordinate transformation.
SELECT From To | SELECT From To
1 RA-Dec (2000) Galactic | 4 Ecliptic RA-Dec
2 Galactic RA-DEC | 5 Ecliptic Galactic
3 RA-Dec Ecliptic | 6 Galactic Ecliptic
If not supplied as a parameter or keyword, then EULER will prompt for
the value of SELECT
Celestial coordinates (RA, Dec) should be given in equinox J2000
unless the /FK4 keyword is set.
OUTPUTS:
AO - Output Longitude in DEGREES, always double precision
BO - Output Latitude in DEGREES, always double precision
OPTIONAL INPUT KEYWORD:
/FK4 - If this keyword is set and non-zero, then input and output
celestial and ecliptic coordinates should be given in equinox
B1950.
/RADIAN - if set, then all input and output angles are in radians rather
than degrees.
SELECT - The coordinate conversion integer (1-6) may alternatively be
specified as a keyword
EXAMPLE:
Find the Galactic coordinates of Cyg X-1 (ra=299.590315, dec=35.201604)
IDL> ra = 299.590315d
IDL> dec = 35.201604d
IDL> euler,ra,dec,glong,glat,1 & print,glong,glat
71.334990, 3.0668335
REVISION HISTORY:
Written W. Landsman, February 1987
Adapted from Fortran by Daryl Yentis NRL
Made J2000 the default, added /FK4 keyword W. Landsman December 1998
Add option to specify SELECT as a keyword W. Landsman March 2003
Use less virtual memory for large input arrays W. Landsman June 2008
Added /RADIAN input keyword W. Landsman Sep 2008
(See astrolib/pro/euler.pro)
EXPAND_TILDE()
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NAME:
EXPAND_TILDE()
PURPOSE:
Expand tilde in UNIX directory names
CALLING SEQUENCE:
IDL> output=expand_tilde(input)
INPUTS:
INPUT = input file or directory name, scalar string
OUTPUT:
Returns expanded filename, scalar string
EXAMPLES:
output=expand_tilde('~zarro/test.doc')
---> output='/usr/users/zarro'
NOTES:
This version of EXPAND_TILDE differs from the version in the Solar
Library in that it does not call the functions EXIST and IDL_RELEASE.
However, it should work identically.
PROCEDURE CALLS:
None.
REVISION HISTORY:
Version 1, 17-Feb-1997, D M Zarro. Written
Transfered from Solar Library W. Landsman Sep. 1997
Made more robust D. Zarro/W. Landsman Sep. 2000
Made even more robust (since things like ~zarro weren't being expanded)
Zarro (EITI/GSFC, Mar 2001)
(See astrolib/pro/expand_tilde.pro)
EXTAST
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NAME:
EXTAST
PURPOSE:
Extract ASTrometry parameters from a FITS image header.
EXPLANATION:
Extract World Coordinate System information
( http://fits.gsfc.nasa.gov/fits_wcs.html ) from a FITS header and
place it into an IDL structure.
CALLING SEQUENCE:
EXTAST, hdr, [ astr, noparams, ALT= ]
INPUT:
HDR - variable containing the FITS header (string array)
OUTPUTS:
ASTR - Anonymous structure containing astrometry info from the FITS
header ASTR always contains the following tags (even though
some projections do not require all the parameters)
.NAXIS - 2 element array giving image size
.CD - 2 x 2 array containing the astrometry parameters CD1_1 CD1_2
in DEGREES/PIXEL CD2_1 CD2_2
.CDELT - 2 element double vector giving physical increment at the
reference pixel
.CRPIX - 2 element double vector giving X and Y coordinates of reference
pixel (def = NAXIS/2) in FITS convention (first pixel is 1,1)
.CRVAL - 2 element double precision vector giving R.A. and DEC of
reference pixel in DEGREES
.CTYPE - 2 element string vector giving projection types, default
['RA---TAN','DEC--TAN']
.LONGPOLE - scalar giving native longitude of the celestial pole
(default = 180 for zenithal projections)
.LATPOLE - scalar giving native latitude of the celestial pole default=0)
.PV2 - Vector of projection parameter associated with latitude axis
PV2 will have up to 21 elements for the ZPN projection, up to 3
for the SIN projection and no more than 2 for any other
projection
.DISTORT - optional substructure specifying any distortion parameters
currently implemented only for "SIP" (Spitzer Imaging
Polynomial) distortion parameters
NOPARAMS - Scalar indicating the results of EXTAST
-1 = Failure - Header missing astrometry parameters
1 = Success - Header contains CROTA + CDELT (AIPS-type) astrometry
2 = Success - Header contains CDn_m astrometry, rec.
3 = Success - Header contains PCn_m + CDELT astrometry.
4 = Success - Header contains ST Guide Star Survey astrometry
(see gsssextast.pro )
OPTIONAL INPUT/OUTPUT KEYWORDS:
ALT - single character 'A' through 'Z' or ' ' specifying an alternate
astrometry system present in the FITS header. The default is
to use the primary astrometry or ALT = ' '. If /ALT is set,
then this is equivalent to ALT = 'A'. See Section 3.3 of
Greisen & Calabretta (2002, A&A, 395, 1061) for information about
alternate astrometry keywords. If not set on input, then
ALT is set to ' ' on output.
PROCEDURE:
EXTAST checks for astrometry parameters in the following order:
(1) the CD matrix PC1_1,PC1_2...plus CDELT*, CRPIX and CRVAL
(2) the CD matrix CD1_1,CD1_2... plus CRPIX and CRVAL.
(3) CROTA2 (or CROTA1) and CDELT plus CRPIX and CRVAL.
All three forms are valid FITS according to the paper "Representations
of World Coordinates in FITS by Greisen and Calabretta (2002, A&A, 395,
1061 http://fits.gsfc.nasa.gov/fits_wcs.html ) although form (1) is
preferred.
NOTES:
1. An anonymous structure is created to avoid structure definition
conflicts. This is needed because some projection systems
require additional dimensions (i.e. spherical cube
projections require a specification of the cube face).
2, Some FITS headers (e.g.from HST/ACS) include SIP forward distortion
coefficients but do not include the reverse coefficients. Currently,
EXTAST only gives a warning that the reverse coefficients (RA,Dec to
X,Y) are not present. EXTAST should actually compute
the inverse coefficients, but this is not yet implemented..
PROCEDURES CALLED:
GSSSEXTAST, ZPARCHECK
REVISION HISTORY
Written by B. Boothman 4/15/86
Accept CD001001 keywords 1-3-88
Accept CD1_1, CD2_1... keywords W. Landsman Nov. 92
Recognize GSSS FITS header W. Landsman June 94
Get correct sign, when converting CDELT* to CD matrix for right-handed
coordinate system W. Landsman November 1998
Consistent conversion between CROTA and CD matrix October 2000
CTYPE = 'PIXEL' means no astrometry params W. Landsman January 2001
Don't choke if only 1 CTYPE value given W. Landsman August 2001
Recognize PC00n00m keywords again (sigh...) W. Landsman December 2001
Recognize GSSS in ctype also D. Finkbeiner Jan 2002
Introduce ALT keyword W. Landsman June 2003
Fix error introduced June 2003 where free-format values would be
truncated if more than 20 characters. W. Landsman Aug 2003
Further fix to free-format values -- slash need not be present Sep 2003
Default value of LATPOLE is 90.0 W. Landsman February 2004
Allow for distortion substructure, currently implemented only for
SIP (Spitzer Imaging Polynomial) W. Landsman February 2004
Correct LONGPOLE computation if CTYPE = ['*DEC','*RA'] W. L. Feb. 2004
Assume since V5.3 (vector STRMID) W. Landsman Feb 2004
Yet another fix to free-format values W. Landsman April 2004
Introduce PV2 tag to replace PROJP1, PROJP2.. etc. W. Landsman May 2004
Convert NCP projection to generalized SIN W. Landsman Aug 2004
Add NAXIS tag to output structure W. Landsman Jan 2007
.CRPIX tag now Double instead of Float W. Landsman Apr 2007
If duplicate keywords use the *last* value W. Landsman Aug 2008
Fix typo for AZP projection, nonzero longpole N. Cunningham Feb 2009
Give warning if reverse SIP coefficient not present W. Landsman Nov 2011
Allow obsolete CD matrix representations W. Landsman May 2012
(See astrolib/pro/extast.pro)
EXTGRP
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NAME:
EXTGRP
PURPOSE:
Extract the group parameter information out of SXREAD output
EXPLANATION:
This procedure extracts the group parameter information out of a
header and parameter variable obtained from SXREAD. This allows
astrometry, photometry and other parameters to be easily SXPARed by
conventional methods and allows the image and header to be saved in
a SIMPLE format.
CALLING SEQUENCE:
ExtGrp, hdr, par
INPUT:
HDR - The header which is to be converted (input and output)
PAR - The Parameter string returned from a call to SXREAD
OUTPUT:
HDR - The converted header, string array
OTHER PROCEDURES CALLED:
SXPAR(), SXADDPAR, SXGPAR(), STRN()
HISTORY:
25-JUN-90 Version 1 written
13-JUL-92 Header finally added to this ancient procedure, code spiffed up
a bit. Now 3 times faster. Added PTYPE comment inclusion. E. Deutsch
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/extgrp.pro)
EXTRAP
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NAME:
EXTRAP
PURPOSE:
This procedure fills in the ends of a one-dimensional array from
interior portions using polynomial extrapolation.
CATEGORY:
Image processing
CALLING SEQUENCE:
EXTRAP, Deg, X, Y, Y2
INPUT POSITIONAL PARAMETERS:
Deg: Degree of polynomial
X: Independent variable
Y: Dependent variable
KEYWORD PARAMETERS:
LIMS: 3-element array giving range of X to be used to fit
polynomial and starting point where extrapolation is
to be substituted; if not given, you click on a plot;
order of elements is [xmin, xmax, xstart]; if LIMS is
specified, then program is silent
OUTPUT POSITIONAL PARAMETERS:
Y2: Dependent variable with extrapolated portion filled in
SIDE EFFECTS:
May pop a window for selecting range.
MODIFICATION HISTORY:
Written by RSH, RITSS, 14 Aug 98
Spiffed up for library. RSH, 6 Oct 98
(See astrolib/pro/skyadj_cube.pro)
FDECOMP
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NAME:
FDECOMP
PURPOSE:
Routine to decompose file name(s) for any operating system.
CALLING SEQUENCE:
FDECOMP, filename, disk, dir, name, qual, [OSFamily = ]
INPUT:
filename - string file name(s), scalar or vector
OUTPUTS:
All the output parameters will have the same number of elements as
input filename
disk - disk name, always '' on a Unix machine, scalar or vector string
dir - directory name, scalar or vector string
name - file name, scalar or vector string
qual - qualifier, set equal to the characters beyond the last "."
OPTIONAL INPUT KEYWORD:
OSFamily - scalar string specifying the operating system, must be either
'Windows' or 'unix'. If not supplied,
then !VERSION.OS_FAMILY is used to determine the OS.
EXAMPLES:
Consider the following file names
unix: file = '/itt/idl71/avg.pro'
Windows: file = 'd:\itt\idl71\avg.pro'
then IDL> FDECOMP, file, disk, dir, name, qual
will return the following
Disk Dir Name Qual
Unix: '' '/itt/idl71/' 'avg' 'pro'
Windows: 'd:' \itt\idl71\ 'avg' 'pro'
NOTES:
(1) The period is removed between the name and qualifier
(2) Unlike the intrinsic FILE_BASENAME() and FILE_DIRNAME() functions,
one can use FDECOMP to decompose a Windows file name on a Unix machine
or a Unix filename on a Windows machine.
ROUTINES CALLED:
None.
HISTORY
version 1 D. Lindler Oct 1986
Include VMS DECNET machine name in disk W. Landsman HSTX Feb. 94
Converted to Mac IDL, I. Freedman HSTX March 1994
Major rewrite to accept vector filenames V5.3 W. Landsman June 2000
Fix cases where disk name not always present W. Landsman Sep. 2000
Make sure version defined for Windows W. Landsman April 2004
Include final delimiter in directory under Windows as advertised
W. Landsman May 2006
Remove VMS support, W. Landsman September 2006
Remove MacOS branch (same as Unix) W. Landsman August 2009
(See astrolib/pro/fdecomp.pro)
FILTER_IMAGE
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NAME:
FILTER_IMAGE
PURPOSE:
Identical to MEDIAN or SMOOTH but handle edges and allow iterations.
EXPLANATION:
Computes the average and/or median of pixels in moving box,
replacing center pixel with the computed average and/or median,
(using the IDL SMOOTH() or MEDIAN() functions).
The main reason for using this function is the options to
also process the pixels at edges and corners of image, and,
to apply iterative smoothing simulating convolution with Gaussian,
and/or to convolve image with a Gaussian kernel. Users might also
look at the function ESTIMATOR_FILTER() introduced in IDL 7.1.
CALLING SEQUENCE:
Result = filter_image( image, SMOOTH=width, MEDIAN = width, /ALL_PIXELS
/ITERATE, FWHM =, /NO_FT_CONVOL)
INPUT:
image = 2-D array (matrix)
OPTIONAL INPUT KEYWORDS:
SMOOTH = scalar (odd) integer specifying the width of a square box
for moving average, in # pixels. /SMOOTH means use box
width = 3 pixels for smoothing.
MEDIAN = scalar (usually odd) integer specifying the width of square
moving box for median filter, in # pixels. /MEDIAN means use
box width = 3 pixels for median filter.
/ALL_PIXELS causes the edges of image to be filtered as well. This
is accomplished by reflecting pixels adjacent to edges outward
(similar to the /EDGE_WRAP keyword in CONVOL).
Note that this is a different algorithm from the /EDGE_TRUNCATE
keyword to SMOOTH or CONVOL, which duplicates the nearest pixel.
/ITERATE means apply smooth(image,3) iteratively for a count of
(box_width-1)/2 times (=radius), when box_width >= 5.
This is equivalent to convolution with a Gaussian PSF
of FWHM = 2 * sqrt( radius ) as radius gets large.
Note that /ALL_PIXELS is automatically applied,
giving better results in the iteration limit.
(also, MEDIAN keyword is ignored when /ITER is specified).
FWHM_GAUSSIAN = Full-width half-max of Gaussian to convolve with image.
FWHM can be a single number (circular beam),
or 2 numbers giving axes of elliptical beam.
/NO_FT_CONVOL causes the convolution to be computed directly,
with intrinsic IDL CONVOL function. The default is to use
FFT when factors of size are all LE 13. Note that
external function convolve.pro handles both cases)
OPTIONAL INPUT/OUTPUT KEYWORD:
PSF = Array containing the PSF used during the convolution. This
keyword is only active if the FWHM_GAUSSIAN keyword is also
specified. If PSF is undefined on input, then upon output it
contains the Gaussian convolution specified by the FWHM_GAUSSIAN
keyword. If the PSF array is defined on input then it is used
as the convolution kernel, the value of the FWHM_GAUSSIAN keyword
is ignored. Typically, on a first call set PSF to an undefined
variable, which can be reused for subsequent calls to prevent
recalculation of the Gaussian PSF.
RESULT:
Function returns the smoothed, median filtered, or convolved image.
If both SMOOTH and MEDIAN are specified, median filter is applied first.
If only SMOOTH is applied, then output is of same type as input. If
either MEDIAN or FWHM_GAUSSIAN is supplied than the output is at least
floating (double if the input image is double).
EXAMPLES:
To apply 3x3 moving median filter and
then 3x3 moving average, both applied to all pixels:
Result = filter_image( image, /SMOOTH, /MEDIAN, /ALL )
To iteratively apply 3x3 moving average filter for 4 = (9-1)/2 times,
thus approximating convolution with Gaussian of FWHM = 2*sqrt(4) = 4 :
Result = filter_image( image, SMOOTH=9, /ITER )
To convolve all pixels with Gaussian of FWHM = 3.7 x 5.2 pixels:
Result = filter_image( image, FWHM=[3.7,5.2], /ALL )
EXTERNAL CALLS:
function psf_gaussian
function convolve
pro factor
function prime ;all these called only if FWHM is specified
PROCEDURE:
If both /ALL_PIXELS (or /ITERATE) keywords are set then
create a larger image by reflecting the edges outward, then call the
IDL MEDIAN() or SMOOTH() function on the larger image, and just return
the central part (the original size image).
NAN values are recognized during calls to MEDIAN() or SMOOTH(), but
not for convolution with a Gaussian (FWHM keyword supplied).
HISTORY:
Written, 1991, Frank Varosi, NASA/GSFC.
FV, 1992, added /ITERATE option.
FV, 1993, added FWHM_GAUSSIAN= option.
Use /EVEN call to median, recognize NAN values in SMOOTH
W. Landsman June 2001
Added PSF keyword, Bjorn Heijligers/WL, September 2001
Keep same output data type if /ALL_PIXELS supplied A. Steffl Mar 2011
(See astrolib/pro/filter_image.pro)
FIND
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NAME:
FIND
PURPOSE:
Find positive brightness perturbations (i.e stars) in an image
EXPLANATION:
Also returns centroids and shape parameters (roundness & sharpness).
Adapted from 1991 version of DAOPHOT, but does not allow for bad pixels
and uses a slightly different centroid algorithm.
Modified in March 2008 to use marginal Gaussian fits to find centroids
CALLING SEQUENCE:
FIND, image, [ x, y, flux, sharp, round, hmin, fwhm, roundlim, sharplim
PRINT= , /SILENT, /MONITOR]
INPUTS:
image - 2 dimensional image array (integer or real) for which one
wishes to identify the stars present
OPTIONAL INPUTS:
FIND will prompt for these parameters if not supplied
hmin - Threshold intensity for a point source - should generally
be 3 or 4 sigma above background RMS
fwhm - FWHM (in pixels) to be used in the convolve filter
sharplim - 2 element vector giving low and high cutoff for the
sharpness statistic (Default: [0.2,1.0] ). Change this
default only if the stars have significantly larger or
or smaller concentration than a Gaussian
roundlim - 2 element vector giving low and high cutoff for the
roundness statistic (Default: [-1.0,1.0] ). Change this
default only if the stars are significantly elongated.
OPTIONAL INPUT KEYWORDS:
/MONITOR - Normally, FIND will display the results for each star
only if no output variables are supplied. Set /MONITOR
to always see the result of each individual star.
/SILENT - set /SILENT keyword to suppress all output display
PRINT - if set and non-zero then FIND will also write its results to
a file find.prt. Also one can specify a different output file
name by setting PRINT = 'filename'.
OPTIONAL OUTPUTS:
x - vector containing x position of all stars identified by FIND
y- vector containing y position of all stars identified by FIND
flux - vector containing flux of identified stars as determined
by a Gaussian fit. Fluxes are NOT converted to magnitudes.
sharp - vector containing sharpness statistic for identified stars
round - vector containing roundness statistic for identified stars
NOTES:
(1) The sharpness statistic compares the central pixel to the mean of
the surrounding pixels. If this difference is greater than the
originally estimated height of the Gaussian or less than 0.2 the height of the
Gaussian (for the default values of SHARPLIM) then the star will be
rejected.
(2) More recent versions of FIND in DAOPHOT allow the possibility of
ignoring bad pixels. Unfortunately, to implement this in IDL
would preclude the vectorization made possible with the CONVOL function
and would run extremely slowly.
(3) Modified in March 2008 to use marginal Gaussian distributions to
compute centroid. (Formerly, find.pro determined centroids by locating
where derivatives went to zero -- see cntrd.pro for this algorithm.
This was the method used in very old (~1984) versions of DAOPHOT. )
As discussed in more detail in the comments to the code, the centroid
computation here is the same as in IRAF DAOFIND but differs slightly
from the current DAOPHOT.
PROCEDURE CALLS:
GETOPT()
REVISION HISTORY:
Written W. Landsman, STX February, 1987
ROUND now an internal function in V3.1 W. Landsman July 1993
Change variable name DERIV to DERIVAT W. Landsman Feb. 1996
Use /PRINT keyword instead of TEXTOUT W. Landsman May 1996
Changed loop indices to type LONG W. Landsman Aug. 1997
Replace DATATYPE() with size(/TNAME) W. Landsman Nov. 2001
Fix problem when PRINT= filename W. Landsman October 2002
Fix problems with >32767 stars D. Schlegel/W. Landsman Sep. 2004
Fix error message when no stars found S. Carey/W. Landsman Sep 2007
Rewrite centroid computation to use marginal Gaussians W. Landsman
Mar 2008
Added Monitor keyword, /SILENT now suppresses all output
W. Landsman Nov 2008
Work when threshold is negative (difference images) W. Landsman May 2010
(See astrolib/pro/find.pro)
FINDPRO
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NAME:
FINDPRO
PURPOSE:
Find all locations of a procedure in the IDL !PATH
EXPLANATION:
FINDPRO searces for the procedure name (as a .pro or a .sav file) in all
IDL libraries or directories given in the !PATH system variable. This
differs from the intrinsic FILE_WHICH() function which only finds the
first occurence of the procedure name.
CALLING SEQUENCE:
FINDPRO, [ Proc_Name, /NoPrint, DirList = , ProList = ]
OPTIONAL INPUT:
Proc_Name - Character string giving the name of the IDL procedure or
function. Do not include the ".pro" extension. If Proc_Name is
omitted, the program will prompt for PROC_NAME. "*" wildcards
are permitted.
OPTIONAL KEYWORD INPUT:
/NoPrint - if set, then the file's path is not printed on the screen and
absolutely no error messages are printed on the screen. If not
set, then - since the MESSAGE routine is used - error messages
will be printed but the printing of informational messages
depends on the value of the !Quiet variable.
OPTIONAL KEYWORD OUTPUTS:
DirList - The directories in which the file is located are returned in
the keyword as a string array.
If the procedure is an intrinsic IDL procedure, then the
value of DirList = ['INTRINSIC'].
If the procedure is not found, the value of DirList = [''].
ProList - The list (full pathnames) of procedures found. Useful if you
are looking for the name of a procedure using wildcards.
The order of the names in DirList and ProList is identical to the order
in which the procedure name appears in the !PATH
PROCEDURE:
The system variable !PATH is parsed using EXPAND_PATH into individual
directories. FILE_SEARCH() is used to search the directories for
the procedure name. If not found in !PATH, then the name is compared
with the list of intrinsic IDL procedures given by the ROUTINE_INFO()
function.
EXAMPLE:
(1) Find the procedure CURVEFIT. Assume for this example that the user
also has a copy of the curvefit.pro procedure in her home directory
on a Unix machine.
IDL> findpro, 'curvefit', DIRLIST=DirList
Procedure curvefit.pro found in directory /home/user/.
Procedure curvefit.pro found in directory /software/IDL/idl82/lib/
IDL> help, DirList
DIRLIST STRING = Array(2)
IDL> help, DirList[0], DirList[1]
STRING = '/home/user'
STRING = '/software/IDL/idl82/lib/'
(2) Find all procedures in one's !path containing the characters "zoom"
IDL> findpro,'*zoom*'
RESTRICTIONS:
User will be unable to find a path for a native IDL function
or procedure, or for a FORTRAN or C routine added with CALL_EXTERNAL.
Remember that Unix is case sensitive, and most procedures will be in
lower case.
PROCEDURES USED:
FDECOMP -- Decompose file name
REVISION HISTORY:
Based on code extracted from the GETPRO procedure, J. Parker 1994
Use the intrinsic EXPAND_PATH function W. Landsman Nov. 1994
Use ROUTINE_NAMES() to check for intrinsic procs W. Landsman Jul 95
Added Macintosh, WINDOWS compatibility W. Landsman Sep. 95
Removed spurious first element in PROLIST W. Landsman March 1997
Don't include duplicate directories in !PATH WL May 1997
Use ROUTINE_INFO instead of undocumented ROUTINE_NAMES W.L. October 1998
Also check for save sets W. Landsman October 1999
Force lower case check for VMS W. Landsman January 2000
Only return .pro or .sav files in PROLIST W. Landsman January 2002
Force lower case check for .pro and .sav D. Swain September 2002
Use FILE_SEARCH() if V5.5 or later W. Landsman June 2006
Assume since V55, remove VMS support W. Landsman Sep. 2006
Assume since V6.0, use file_basename() W.Landsman Feb 2009
Specify whether an intrinsic function or procedure W.L. Jan 2013
(See astrolib/pro/findpro.pro)
FIND_ALL_DIR()
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NAME:
FIND_ALL_DIR()
PURPOSE:
Finds all directories under a specified directory.
EXPLANATION:
This routine finds all the directories in a directory tree when the
root of the tree is specified. This provides the same functionality as
having a directory with a plus in front of it in the environment
variable IDL_PATH.
CALLING SEQUENCE:
Result = FIND_ALL_DIR( PATH )
PATHS = FIND_ALL_DIR('+mypath', /PATH_FORMAT)
PATHS = FIND_ALL_DIR('+mypath1:+mypath2')
INPUTS:
PATH = The path specification for the top directory in the tree.
Optionally this may begin with the '+' character but the action
is the same unless the PLUS_REQUIRED keyword is set.
One can also path a series of directories separated
by the correct character ("," for VMS, ":" for Unix)
OUTPUTS:
The result of the function is a list of directories starting from the
top directory passed and working downward from there. Normally, this
will be a string array with one directory per array element, but if
the PATH_FORMAT keyword is set, then a single string will be returned,
in the correct format to be incorporated into !PATH.
OPTIONAL INPUT KEYWORDS:
PATH_FORMAT = If set, then a single string is returned, in
the format of !PATH.
PLUS_REQUIRED = If set, then a leading plus sign is required
in order to expand out a directory tree.
This is especially useful if the input is a
series of directories, where some components
should be expanded, but others shouldn't.
RESET = Often FIND_ALL_DIR is used with logical names. It
can be rather slow to search through these subdirectories.
The /RESET keyword can be used to redefine an environment
variable so that subsequent calls don't need to look for the
subdirectories.
To use /RESET, the PATH parameter must contain the name of a
*single* environment variable. For example
setenv,'FITS_DATA=+/datadisk/fits'
dir = find_all_dir('FITS_DATA',/reset,/plus)
The /RESET keyword is usually combined with /PLUS_REQUIRED.
PROCEDURE CALLS:
DEF_DIRLIST, FIND_WITH_DEF(), BREAK_PATH()
RESTRICTIONS:
PATH must point to a directory that actually exists.
REVISION HISTORY:
Version 11, Zarro (SM&A/GSFC), 23-March-00
Removed all calls to IS_DIR
Version 12, William Thompson, GSFC, 02-Feb-2001
In Windows, use built-in expand_path if able.
Version 13, William Thompson, GSFC, 23-Apr-2002
Follow logical links in Unix
(Suggested by Pascal Saint-Hilaire)
Version 14, Zarro (EER/GSFC), 26-Oct-2002
Saved/restored current directory to protect against
often mysterious directory changes caused by
spawning FIND in Unix
Version 15, William Thompson, GSFC, 9-Feb-2004
Resolve environment variables in Windows.
Version : Version 16 W. Landsman GSFC Sep 2006
Remove VMS support
(See astrolib/pro/find_all_dir.pro)
FIND_WITH_DEF()
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NAME:
FIND_WITH_DEF()
PURPOSE:
Searches for files with a default path and extension.
EXPLANATION:
Finds files using default paths and extensions, Using this routine
together with environment variables allows an OS-independent approach
to finding files.
CALLING SEQUENCE:
Result = FIND_WITH_DEF( FILENAME, PATHS [, EXTENSIONS ] )
INPUTS:
FILENAME = Name of file to be searched for. It may either be a
complete filename, or the path or extension could be left
off, in which case the routine will attempt to find the
file using the default paths and extensions.
PATHS = One or more default paths to use in the search in case
FILENAME does not contain a path itself. The individual
paths are separated by commas, although in UNIX, colons
can also be used. In other words, PATHS has the same
format as !PATH, except that commas can be used as a
separator regardless of operating system. The current
directory is always searched first, unless the keyword
NOCURRENT is set.
A leading $ can be used in any path to signal that what
follows is an environmental variable, but the $ is not
necessary. Environmental variables can themselves contain
multiple paths.
OPTIONAL INPUTS:
EXTENSIONS = Scalar string giving one or more extensions to append to
end of filename if the filename does not contain one (e.g.
".dat"). The period is optional. Multiple extensions can
be separated by commas or colons.
OUTPUTS:
The result of the function is the name of the file if successful, or
the null string if unsuccessful.
OPTIONAL INPUT KEYWORDS:
NOCURRENT = If set, then the current directory is not searched.
RESET = The FIND_WITH_DEF routine supports paths which are
preceeded with the plus sign to signal that all
subdirectories should also be searched. Often this is
used with logical names. It can be rather slow to search
through these subdirectories. The /RESET keyword can be
used to redefine an environment variable so that
subsequent calls don't need to look for the
subdirectories.
To use /RESET, the PATHS parameter must contain the name
of a *single* environment variable. For example
setenv,'FITS_DATA=+/datadisk/fits'
file = find_with_def('test.fits','FITS_DATA',/reset)
EXAMPLE:
FILENAME = ''
READ, 'File to open: ', FILENAME
FILE = FIND_WITH_DEF( FILENAME, 'SERTS_DATA', '.fix' )
IF FILE NE '' THEN ...
PROCEDURE CALLS:
BREAK_PATH(), FIND_ALL_DIR(), STR_SEP()
REVISION HISTORY:
Version 1, William Thompson, GSFC, 3 May 1993.
Removed trailing / and : characters.
Fixed bugs
Allow for commas within values of logical names.
Added keyword NOCURRENT.
Changed to call BREAK_PATH
Version 2, William Thompson, GSFC, 3 November 1994
Made EXTENSIONS optional.
Version 3, William Thompson, GSFC, 30 April 1996
Call FIND_ALL_DIR to resolve any plus signs.
Version 4, S.V. Haugan, UiO, 5 June 1996
Using OPENR,..,ERROR=ERROR to avoid an IDL 3.6
internal nesting error.
Version 5, R.A. Schwartz, GSFC, 11 July 1996
Use SPEC_DIR to interpret PATH under VMS
Version 6, William Thompson, GSFC, 5 August 1996
Took out call to SPEC_DIR (i.e., reverted to version 4). The
use of SPEC_DIR was required to support logical names defined
via SETLOG,/CONFINE. However, it conflicted with the ability
to use logical names with multiple values. Removing the
/CONFINE made it unnecessary to call SPEC_DIR in this routine.
Version 7, William Thompson, GSFC, 6 August 1996
Added keyword RESET
Converted to IDL V5.0 W. Landsman October 1997
Use STRTRIM instead of TRIM, W. Landsman November 1998
Use STRSPLIT instead of STR_SEP W. Landsman July 2002
(See astrolib/pro/find_with_def.pro)
FITEXY
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NAME:
FITEXY
PURPOSE:
Best straight-line fit to data with errors in both coordinates
EXPLANATION:
Linear Least-squares approximation in one-dimension (y = a + b*x),
when both x and y data have errors
CALLING EXAMPLE:
FITEXY, x, y, A, B, X_SIG= , Y_SIG= , [sigma_A_B, chi_sq, q, TOL=]
INPUTS:
x = array of values for independent variable.
y = array of data values assumed to be linearly dependent on x.
REQUIRED INPUT KEYWORDS:
X_SIGMA = scalar or array specifying the standard deviation of x data.
Y_SIGMA = scalar or array specifying the standard deviation of y data.
OPTIONAL INPUT KEYWORD:
TOLERANCE = desired accuracy of minimum & zero location, default=1.e-3.
OUTPUTS:
A_intercept = constant parameter result of linear fit,
B_slope = slope parameter, so that:
( A_intercept + B_slope * x ) approximates the y data.
OPTIONAL OUTPUT:
sigma_A_B = two element array giving standard deviation of
A_intercept and B_slope parameters, respectively.
The standard deviations are not meaningful if (i) the
fit is poor (see parameter q), or (ii) b is so large that
the data are consistent with a vertical (infinite b) line.
If the data are consistent with *all* values of b, then
sigma_A_B = [1e33,e33]
chi_sq = resulting minimum Chi-Square of Linear fit, scalar
q - chi-sq probability, scalar (0-1) giving the probability that
a correct model would give a value equal or larger than the
observed chi squared. A small value of q indicates a poor
fit, perhaps because the errors are underestimated. As
discussed by Tremaine et al. (2002, ApJ, 574, 740) an
underestimate of the errors (e.g. due to an intrinsic dispersion)
can lead to a bias in the derived slope, and it may be worth
enlarging the error bars to get a reduced chi_sq ~ 1
COMMON:
common fitexy, communicates the data for computation of chi-square.
PROCEDURE CALLS:
CHISQ_FITEXY() ;Included in this file
MINF_BRACKET, MINF_PARABOLIC, ZBRENT ;In IDL Astronomy Library
MOMENT(), CHISQR_PDF() ;In standard IDL distribution
PROCEDURE:
From "Numerical Recipes" column by Press and Teukolsky:
in "Computer in Physics", May, 1992 Vol.6 No.3
Also see the 2nd edition of the book "Numerical Recipes" by Press et al.
In order to avoid problems with data sets where X and Y are of very
different order of magnitude the data are normalized before the fitting
process is started. The following normalization is used:
xx = (x - xm) / xs and sigx = x_sigma / xs
where xm = MEAN(x) and xs = STDDEV(x)
yy = (y - ym) / ys and sigy = y_sigma / ys
where ym = MEAN(y) and ys = STDDEV(y)
MODIFICATION HISTORY:
Written, Frank Varosi NASA/GSFC September 1992.
Now returns q rather than 1-q W. Landsman December 1992
Use CHISQR_PDF, MOMENT instead of STDEV,CHI_SQR1 W. Landsman April 1998
Fixed typo for initial guess of slope, this error was nearly
always insignificant W. Landsman March 2000
Normalize X,Y before calculation (from F. Holland) W. Landsman Nov 2006
(See astrolib/pro/fitexy.pro)
FITSDIR
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NAME:
FITSDIR
PURPOSE:
Display selected FITS keywords from the headers of FITS files.
EXPLANATION:
The values of either user-specified or default FITS keywords are
displayed in either the primary header and/or the first extension header.
Unless the /NOSIZE keyword is set, the data size is also displayed.
The default keywords are as follows (with keywords in 2nd row used if
those in the first row not found, and the 3rd row if neither the keywords
in the first or second rows found:)
DATE-OBS TELESCOP OBJECT EXPTIME
TDATEOBS TELNAME TARGNAME INTEG ;First Alternative
DATE OBSERVAT EXPOSURE ;Second Alternative
INSTRUME EXPTIM ;Third Alternative
FITSDIR will also recognize gzip compressed files (must have a .gz
or FTZ extension).
CALLING SEQUENCE:
FITSDIR , [ directory, TEXTOUT =, EXTEN=, KEYWORDS=, /NOSIZE, /NoTELESCOPE
ALT1_KEYWORDS= ,ALT2_KEYWORDS = ,ALT3_KEYWORDS =
OPTIONAL INPUT PARAMETERS:
DIRECTORY - Scalar string giving file name, disk or directory to be
searched. Wildcard file names are allowed. Examples of
valid names include 'iraf/*.fits' (Unix), d:\myfiles\f*.fits',
(Windows) or 'Macintosh HD:Files:*c0f.fits' (Macintosh).
OPTIONAL KEYWORD INPUT PARAMETER
KEYWORDS - FITS keywords to display, as either a vector of strings or as
a comma delimited scalar string, e.g.'testname,dewar,filter'
If not supplied, then the default keywords are 'DATE-OBS',
'TELESCOP','OBJECT','EXPTIME'
ALT1_KEYWORDS - A list (either a vector of strings or a comma delimited
strings of alternative keywords to use if the default
KEYWORDS cannot be found. By default, 'TDATEOBS', is the
alternative to DATE-OBS, 'TELNAME' for 'TELESCOP','TARGNAME'
for 'OBJECT', and 'INTEG' for EXPTIME
ALT2_KEYWORDS - A list (either a vector of strings or a comma delimited
strings of alternative keywords to use if neither KEYWORDS
nor ALT1_KEYWORDS can be found.
ALT3_KEYWORDS - A list (either a vector of strings or a comma delimited
strings of alternative keywords to use if neither KEYWORDS
nor ALT1_KEYWORDS nor ALT2_KEYWORDS can be found.
/NOSIZE - if set then information about the image size is not displayed
TEXTOUT - Controls output device as described in TEXTOPEN procedure
textout=1 TERMINAL using /more option
textout=2 TERMINAL without /more option
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file
textout=7 Append to existing .prt file
textout = filename (default extension of .prt)
EXTEN - Specifies an extension number (/EXTEN works for first extension)
which is checked for the desired keywords.
/NOTELESCOPE - If set, then if the default keywords are used, then the
TELESCOPE (or TELNAME, OBSERVAT, INSTRUME) keywords are omitted
to give more room for display other keywords. The /NOTELESCOP
keyword has no effect if the default keywords are not used.
OUTPUT PARAMETERS:
None.
EXAMPLES:
(1) Print info on all'*.fits' files in the current directory using default
keywords. Include information from the extension header
IDL> fitsdir,/exten
(2) Write a driver program to display selected keywords in HST/ACS drizzled
(*drz) images
pro acsdir
keywords = 'date-obs,targname,detector,filter1,filter2,exptime'
fitsdir,'*drz.fits',key=keywords,/exten
return & end
(3) Write info on all *.fits files in the Unix directory /usr2/smith, to a
file 'smith.txt' using the default keywords, but don't display the value
of the TELESCOPE keyword
IDL> fitsdir ,'/usr2/smith/*.fits',t='smith.txt', /NoTel
PROCEDURE:
FILE_SEARCH() is used to find the specified FITS files. The
header of each file is read, and the selected keywords are extracted.
The formatting is adjusted so that no value is truncated on display.
SYSTEM VARIABLES:
TEXTOPEN (called by FITSDIR) will automatically define the following
non-standard system variables if they are not previously defined:
DEFSYSV,'!TEXTOUT',1
DEFSYSV,'!TEXTUNIT',0
PROCEDURES USED:
FDECOMP, FXMOVE, MRD_HREAD, REMCHAR
TEXTOPEN, TEXTCLOSE
MODIFICATION HISTORY:
Written, W. Landsman, HSTX February, 1993
Search alternate keyword names W.Landsman October 1998
Avoid integer truncation for NAXISi >32767 W. Landsman July 2000
Don't leave open unit W. Landsman July 2000
Added EXTEN keyword, work with compressed files, additional alternate
keywords W. Landsman December 2000
Don't assume floating pt. exposure time W. Landsman September 2001
Major rewrite, KEYWORD & ALT*_KEYWORDS keywords, no truncation,
/NOSIZE keyword W. Landsman, SSAI August 2002
Assume V5.3 or later W. Landsman November 2002
Fix case where no keywords supplied W. Landsman January 2003
NAXIS* values must be integers W. Landsman SSAI June 2003
Trim spaces off of input KEYWORD values W. Landsman March 2004
Treat .FTZ extension as gzip compressed W. Landsman September 2004
Assume since V5.5, file_search() available W. Landsman Aug 2006
Don't assume all images compressed or uncompressed W. L. Apr 2010
Use V6.0 notation W.L. Feb 2011
(See astrolib/pro/fitsdir.pro)
FITSRGB_TO_TIFF
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NAME:
FITSRGB_to_TIFF
PURPOSE:
Combine separate red, green, and blue FITS images into TIFF format
EXPLANATION:
The output TIFF (class R) file can have colors interleaved either
by pixel or image. The colour mix is also adjustable.
CALLING SEQUENCE:
FITSRGB_to_TIFF, path, rgb_files, tiff_name [,/BY_PIXEL, /PREVIEW,
RED= , GREEN =, BLUE =]
INPUTS:
path = file system directory path to the RGB files required.
rgb_files = string array with three components - the red FITS file
filename, the blue FITS file filename and the green FITS
file filename
OUTPUTS:
tiff_name = string containing name of tiff file to be produced
OPTIONAL OUTPUT:
Header = String array containing the header from the FITS file.
OPTIONAL INPUT KEYWORDS:
BY_PIXEL = This causes TIFF file RGB to be interleaved by pixel
rather than the default of by image.
PREVIEW = Allows a 24 bit image to be displayed on the screen
to check the colour mix.
RED = Real number containing the fractional mix of red
GREEN = Real number containing the fractional mix of green
BLUE = Real number containing the fractional mix of blue
EXAMPLE:
Read three FITS files, 'red.fits', 'blue.fits' and 'green.fits' from
the directory '/data/images/space' and output a TIFF file named
'colour.tiff'
IDL> FITSRGB_to_TIFF, '/data/images/space', ['red.fits', $
'blue.fits', 'green.fits'], 'colour.tiff'
Read three FITS files, 'red.fits', 'blue.fits' and 'green.fits' from
the current directory and output a TIFF file named '/images/out.tiff'
In this case, the red image is twice as strong as the green and the
blue is a third more intense. A preview on screen is also wanted.
IDL> FITSRGB_to_TIFF, '.', ['red.fits', $
'blue.fits', 'green.fits'], '/images/out.tiff', $
/PREVIEW, RED=0.5, GREEN=1.0, BLUE=0.666
RESTRICTIONS:
(1) Limited to the ability of the routine READFITS
NOTES:
None
PROCEDURES USED:
Functions: READFITS, CONCAT_DIR
Procedures: WRITE_TIFF
MODIFICATION HISTORY:
16th January 1995 - Written by Carl Shaw, Queen's University Belfast
27 Jan 1995 - W. Landsman, Add CONCAT_DIR for VMS, Windows compatibility
Converted to IDL V5.0 W. Landsman September 1997
Use WRITE_TIFF instead of obsolete TIFF_WRITE W. Landsman December 1998
Cosmetic changes W. Landsman February 2000
(See astrolib/pro/fitsrgb_to_tiff.pro)
FITS_ADD_CHECKSUM
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NAME:
FITS_ADD_CHECKSUM
PURPOSE:
Add or update the CHECKSUM and DATASUM keywords in a FITS header
EXPLANATION:
Follows the 23 May 2002 version of the FITS checksum proposal at
http://heasarc.gsfc.nasa.gov/docs/heasarc/fits/checksum.html
CALLING SEQUENCE:
FITS_ADD_CHECKSUM, Hdr, [ Data, /No_TIMESTAMP, /FROM_IEEE ]
INPUT-OUTPUT:
Hdr - FITS header (string array), it will be updated with new
(or modfied) CHECKSUM and DATASUM keywords
OPTIONAL INPUT:
Data - data array associated with the FITS header. If not supplied, or
set to a scalar, then the program checks whether there is a
DATASUM keyword already in the FITS header containing the 32bit
checksum for the data. if there is no such keyword then there
assumed to be no data array associated with the FITS header.
OPTIONAL INPUT KEYWORDS:
/FROM_IEEE - If this keyword is set, then the input is assumed to be in
big endian format (e.g. an untranslated FITS array). This
keyword only has an effect on little endian machines (e.g.
a Linux box).
/No_TIMESTAMP - If set, then a time stamp is not included in the comment
field of the CHECKSUM and DATASUM keywords. Unless the
/No_TIMESTAMP keyword is set, repeated calls to FITS_ADD_CHECKSUM
with the same header and data will yield different values of
CHECKSUM (as the date stamp always changes). However, use of the
date stamp is recommended in the checksum proposal.
PROCEDURES USED:
CHECKSUM32, FITS_ASCII_ENCODE(), GET_DATE, SXADDPAR, SXPAR()
REVISION HISTORY:
W. Landsman SSAI December 2002
Fix problem with images with a multiple of 2880 bytes. W.L. May 2008
Avoid conversion error when DATASUM is an empty string W.L. June 2008
Don't update DATASUM if not already present and no data array supplied
W.L. July 2008
Make sure input header array has 80 chars/line W.L. Aug 2009
(See astrolib/pro/fits_add_checksum.pro)
FITS_ASCII_ENCODE()
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NAME:
FITS_ASCII_ENCODE()
PURPOSE:
Encode an unsigned longword as an ASCII string to insert in a FITS header
EXPLANATION:
Follows the 23 May 2002 version of the FITS checksum proposal at
http://heasarc.gsfc.nasa.gov/docs/heasarc/fits/checksum.html
CALLING SEQUENCE:
result = FITS_ASCII_ENCODE( sum32)
INPUTS:
sum32 - 32bit *unsigned longword* (e.g. as returned by CHECKSUM32)
RESULT:
A 16 character scalar string suitable for the CHECKSUM keyword
EXAMPLE:
A FITS header/data unit has a checksum of 868229149. Encode the
complement of this value (3426738146) into an ASCII string
IDL> print,FITS_ASCII_ENCODE(3426738146U)
===> "hcHjjc9ghcEghc9g"
METHOD:
The 32bit value is interpreted as a sequence of 4 unsigned 8 bit
integers, and divided by 4. Add an offset of 48b (ASCII '0').
Remove non-alphanumeric ASCII characters (byte values 58-64 and 91-96)
by simultaneously incrementing and decrementing the values in pairs.
Cyclicly shift the string one place to the right.
REVISION HISTORY:
Written W. Landsman SSAI December 2002
(See astrolib/pro/fits_ascii_encode.pro)
FITS_CD_FIX
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NAME:
FITS_CD_FIX
PURPOSE:
Update obsolete representations of the CD matrix in a FITS header
EXPLANATION:
According the paper, "Representations of Celestial Coordinates in FITS"
by Calabretta & Greisen (2002, A&A, 395, 1077, available at
http://fits.gsfc.nasa.gov/fits_wcs.html) the rotation of an image from
standard coordinates is represented by a coordinate description (CD)
matrix. The standard representation of the CD matrix are PCn_m
keywords, but CDn_m keywords (which include the scale factors) are
also allowed. However, earliers drafts of the standard allowed the
keywords forms CD00n00m and PC00n00m. This procedure will convert
FITS CD matrix keywords containing zeros into the standard forms
CDn_m and PCn_m containing only underscores.
CALLING SEQUENCE:
FITS_CD_FIX, Hdr
INPUT-OUTPUT:
HDR - FITS header, 80 x N string array. If the header does not
contain 'CD00n00m' or 'PC00n00m' keywords then it is left
unmodified. Otherwise, the keywords containing integers are
replaced with those containing underscores.
OPTIONAL KEYWORD INPUT
/REVERSE - this keyword does nothing, but is kept for compatibility with
earlier versions.
PROCEDURES USED:
SXADDPAR, SXDELPAR, SXPAR()
REVISION HISTORY:
Written W. Landsman Feb 1990
Major rewrite Feb 1994
Converted to IDL V5.0 W. Landsman September 1997
Use double precision formatting of CD matrix W. Landsman April 2000
Major rewrite to convert only to forms recognized by the Greisen
& Calabretta standard W. Landsman July 2003
(See astrolib/pro/fits_cd_fix.pro)
FITS_CLOSE
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NAME:
FITS_CLOSE
*PURPOSE:
Close a FITS data file
*CATEGORY:
INPUT/OUTPUT
*CALLING SEQUENCE:
FITS_CLOSE,fcb
*INPUTS:
FCB: FITS control block returned by FITS_OPEN.
*KEYWORD PARAMETERS:
/NO_ABORT: Set to return to calling program instead of a RETALL
when an I/O error is encountered. If set, the routine will
return a non-null string (containing the error message) in the
keyword MESSAGE. If /NO_ABORT not set, then FITS_CLOSE will
print the message and issue a RETALL
MESSAGE = value: Output error message
*EXAMPLES:
Open a FITS file, read some data, and close it with FITS_CLOSE
FITS_OPEN,'infile',fcb
FITS_READ,fcb,data
FITS_READ,fcb,moredata
FITS_CLOSE,fcb
*HISTORY:
Written by: D. Lindler August, 1995
Converted to IDL V5.0 W. Landsman September 1997
Do nothing if fcb an invalid structure D. Schlegel/W. Landsman Oct. 2000
Return Message='' for to signal normal operation W. Landsman Nov. 2000
(See astrolib/pro/fits_close.pro)
FITS_HELP
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NAME:
FITS_HELP
PURPOSE:
To print a summary of the primary data units and extensions in a
FITS file.
;
CALLING SEQUENCE:
FITS_HELP,filename_or_fcb
INPUTS:
FILENAME_OR_FCB - name of the fits file or the FITS Control Block (FCB)
structure returned by FITS_OPEN. The file name is allowed
to be gzip compressed (with a .gz extension)
OUTPUTS:
A summary of the FITS file is printed. For each extension, the values
of the XTENSION, EXTNAME EXTVER EXTLEVEL BITPIX GCOUNT, PCOUNT NAXIS
and NAXIS* keywords are displayed.
EXAMPLES:
FITS_HELP,'myfile.fits'
FITS_OPEN,'anotherfile.fits',fcb
FITS_HELP,fcb
PROCEDURES USED:
FITS_OPEN, FITS_CLOSE
HISTORY:
Written by: D. Lindler August, 1995
Converted to IDL V5.0 W. Landsman September 1997
Don't truncate EXTNAME values at 10 chars W. Landsman Feb. 2005
Use V6.0 notation W. Landsman Jan 2012
(See astrolib/pro/fits_help.pro)
FITS_INFO
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NAME:
FITS_INFO
PURPOSE:
Provide information about the contents of a FITS file
EXPLANATION:
Information includes number of header records and size of data array.
Applies to primary header and all extensions. Information can be
printed at the terminal and/or stored in a common block
This routine is mostly obsolete, and better results can be usually be
performed with FITS_HELP (for display) or FITS_OPEN (to read FITS
information into a structure)
CALLING SEQUENCE:
FITS_INFO, Filename, [ /SILENT , TEXTOUT = , N_ext =, EXTNAME= ]
INPUT:
Filename - Scalar string giving the name of the FITS file(s)
Can include wildcards such as '*.fits', or regular expressions
allowed by the FILE_SEARCH() function. One can also search
gzip compressed FITS files, but their extension must
end in .gz or .ftz.
OPTIONAL INPUT KEYWORDS:
/SILENT - If set, then the display of the file description on the
terminal will be suppressed
TEXTOUT - specifies output device.
textout=1 TERMINAL using /more option
textout=2 TERMINAL without /more option
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file, see TEXTOPEN
textout=7 append to existing file
textout = filename (default extension of .prt)
If TEXTOUT is not supplied, then !TEXTOUT is used
OPTIONAL OUTPUT KEYWORDS:
The following keyowrds are for use when only one file is processed
N_ext - Returns an integer scalar giving the number of extensions in
the FITS file
extname - returns a list containing the EXTNAME keywords for each
extension.
COMMON BLOCKS
DESCRIPTOR = File descriptor string of the form N_hdrrec Naxis IDL_type
Naxis1 Naxis2 ... Naxisn [N_hdrrec table_type Naxis
IDL_type Naxis1 ... Naxisn] (repeated for each extension)
For example, the following descriptor
167 2 4 3839 4 55 BINTABLE 2 1 89 5
indicates that the primary header containing 167 lines, and
the primary (2D) floating point image (IDL type 4)
is of size 3839 x 4. The first extension header contains
55 lines, and the byte (IDL type 1) table array is of size
89 x 5.
The DESCRIPTOR is *only* computed if /SILENT is set.
EXAMPLE:
Display info about all FITS files of the form '*.fit' in the current
directory
IDL> fits_info, '*.fit'
Any time a *.fit file is found which is *not* in FITS format, an error
message is displayed at the terminal and the program continues
PROCEDURES USED:
GETTOK(), MRD_SKIP, STRN(), SXPAR(), TEXTOPEN, TEXTCLOSE
SYSTEM VARIABLES:
The non-standard system variables !TEXTOUT and !TEXTUNIT will be
created by FITS_INFO if they are not previously defined.
DEFSYSV,'!TEXTOUT',1
DEFSYSV,'!TEXTUNIT',0
See TEXTOPEN.PRO for more info
MODIFICATION HISTORY:
Written, K. Venkatakrishna, Hughes STX, May 1992
Added N_ext keyword, and table_name info, G. Reichert
Work on *very* large FITS files October 92
More checks to recognize corrupted FITS files February, 1993
Proper check for END keyword December 1994
Correctly size variable length binary tables WBL December 1994
EXTNAME keyword can be anywhere in extension header WBL January 1998
Correctly skip past extensions with no data WBL April 1998
Converted to IDL V5.0, W. Landsman, April 1998
No need for !TEXTOUT if /SILENT D.Finkbeiner February 2002
Define !TEXTOUT if needed. R. Sterner, 2002 Aug 27
Work on gzip compressed files for V5.3 or later W. Landsman 2003 Jan
Improve speed by only reading first 36 lines of header
Count headers with more than 32767 lines W. Landsman Feb. 2003
Assume since V5.3 (OPENR,/COMPRESS) W. Landsman Feb 2004
EXTNAME keyword can be anywhere in extension header again
WBL/S. Bansal Dec 2004
Read more than 200 extensions WBL March 2005
Work for FITS files with SIMPLE=F WBL July 2005
Assume since V5.4, fstat.compress available WBL April 2006
Added EXTNAME as an IDL keyword to return values. M. Perrin Dec 2007
make Ndata a long64 to deal with large files. E. Hivon Mar 2008
For GDL compatibility, first check if file is compressed before using
OPENR,/COMPRESS B. Roukema/WL Apr 2010
Increased nmax (max number of extensions) from 400 to 2000 Sept 2012
Correctly fills EXTNAME when SILENT is set EH Jan 2013
(See astrolib/pro/fits_info.pro)
FITS_OPEN
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NAME:
FITS_OPEN
PURPOSE:
Opens a FITS (Flexible Image Transport System) data file.
EXPLANATION:
Used by FITS_READ and FITS_WRITE
CALLING SEQUENCE:
FITS_OPEN, filename, fcb
INPUTS:
filename : name of the FITS file to open, scalar string
FITS_OPEN can also open gzip compressed (.gz) file *for
reading only*, although there is a performance penalty
FPACK ( http://heasarc.gsfc.nasa.gov/fitsio/fpack/ )
compressed FITS files can be read provided that the FPACK
software is installed.
*OUTPUTS:
fcb : (FITS Control Block) a IDL structure containing information
concerning the file. It is an input to FITS_READ, FITS_WRITE
FITS_CLOSE and MODFITS.
INPUT KEYWORD PARAMETERS:
/APPEND: Set to append to an existing file.
/FPACK - Signal that the file is compressed with the FPACK software.
http://heasarc.gsfc.nasa.gov/fitsio/fpack/ ) By default,
FITS_OPEN assumes that if the file name extension ends in
.fz that it is fpack compressed. The FPACK software must
be installed on the system
/HPRINT - print headers with routine HPRINT as they are read.
(useful for debugging a strange file)
/NO_ABORT: Set to quietly return to calling program when an I/O error
is encountered, and return a non-null string
(containing the error message) in the keyword MESSAGE.
If /NO_ABORT not set, then FITS_OPEN will display the error
message and return to the calling program.
/UPDATE Set this keyword to open an existing file for update
/WRITE: Set this keyword to open a new file for writing.
OUTPUT KEYWORD PARAMETERS:
MESSAGE = value: Output error message. If the FITS file was opened
successfully, then message = ''.
NOTES:
The output FCB should be passed to the other FITS routines (FITS_OPEN,
FITS_READ, FITS_HELP, and FITS_WRITE). It has the following structure
when FITS_OPEN is called without /WRITE or /APPEND keywords set.
FCB.FILENAME - name of the input file
.UNIT - unit number the file is opened to
.FCOMPRESS - 1 if unit is a FPACK compressed file opened with
a pipe to SPAWN
.NEXTEND - number of extensions in the file.
.XTENSION - string array giving the extension type for each
extension.
.EXTNAME - string array giving the extension name for each
extension. (null string if not defined the extension)
.EXTVER - vector of extension version numbers (0 if not
defined)
.EXTLEVEL - vector of extension levels (0 if not defined)
.GCOUNT - vector with the number of groups in each extension.
.PCOUNT - vector with parameter count for each group
.BITPIX - BITPIX for each extension with values
8 byte data
16 short word integers
32 long word integers
-32 IEEE floating point
-64 IEEE double precision floating point
.NAXIS - number of axes for each extension. (0 for null data
units)
.AXIS - 2-D array where axis(*,N) gives the size of each axes
for extension N
.START_HEADER - vector giving the starting byte in the file
where each extension header begins
.START_DATA - vector giving the starting byte in the file
where the data for each extension begins
.HMAIN - keyword parameters (less standard required FITS
keywords) for the primary data unit.
.OPEN_FOR_WRITE - flag (0= open for read, 1=open for write,
2=open for update)
.LAST_EXTENSION - last extension number read.
.RANDOM_GROUPS - 1 if the PDU is random groups format,
0 otherwise
.NBYTES - total number of (uncompressed) bytes in the FITS file
When FITS open is called with the /WRITE or /APPEND option, FCB
contains:
FCB.FILENAME - name of the input file
.UNIT - unit number the file is opened to
.NEXTEND - number of extensions in the file.
.OPEN_FOR_WRITE - flag (1=open for write, 2=open for append
3=open for update)
EXAMPLES:
Open a FITS file for reading:
FITS_OPEN,'myfile.fits',fcb
Open a new FITS file for output:
FITS_OPEN,'newfile.fits',fcb,/write
PROCEDURES USED:
GET_PIPE_FILESIZE (for Fcompress'ed files) HPRINT, SXDELPAR, SXPAR()
HISTORY:
Written by: D. Lindler August, 1995
July, 1996 NICMOS Modified to allow open for overwrite
to allow primary header to be modified
DJL Oct. 15, 1996 corrected to properly extend AXIS when more
than 100 extensions present
Converted to IDL V5.0 W. Landsman September 1997
Use Message = '' rather than !ERR =1 as preferred signal of normal
operation W. Landsman November 2000
Lindler, Dec, 2001, Modified to use 64 bit words for storing byte
positions within the file to allow support for very large
files
Work with gzip compressed files W. Landsman January 2003
Fix gzip compress for V5.4 and earlier W.Landsman/M.Fitzgerald Dec 2003
Assume since V5.3 (STRSPLIT, OPENR,/COMPRESS) W. Landsman Feb 2004
Treat FTZ extension as gzip compressed W. Landsman Sep 2004
Assume since V5.4 fstat.compress available W. Landsman Apr 2006
FCB.Filename now expands any wildcards W. Landsman July 2006
Make ndata 64bit for very large files B. Garwood/W. Landsman Sep 2006
Open with /SWAP_IF_LITTLE_ENDIAN, remove obsolete keywords to OPEN
W. Landsman Sep 2006
Warn that one cannot open a compressed file for update W.L. April 2007
Use post-V6.0 notation W.L. October 2010
Support FPACK compressed files, new .FCOMPRESS tag to FCB structure
W.L. December 2010
Read gzip'ed files even if gzip is not installed W.L. October 2012
(See astrolib/pro/fits_open.pro)
FITS_READ
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NAME:
FITS_READ
PURPOSE:
To read a FITS file.
CALLING SEQUENCE:
FITS_READ, filename_or_fcb, data [,header, group_par]
INPUTS:
FILENAME_OR_FCB - this parameter can be the FITS Control Block (FCB)
returned by FITS_OPEN or the file name of the FITS file. If
a file name is supplied, FITS_READ will open the file with
FITS_OPEN and close the file with FITS_CLOSE before exiting.
When multiple extensions are to be read from the file, it is
more efficient for the user to call FITS_OPEN and leave the
file open until all extensions are read. FPACK
( http://heasarc.gsfc.nasa.gov/fitsio/fpack/ ) compressed FITS
files can be read provided that the FPACK software is installed.
OUTPUTS:
DATA - data array. If /NOSCALE is specified, BSCALE and BZERO
(if present in the header) will not be used to scale the data.
If Keywords FIRST and LAST are used to read a portion of the
data or the heap portion of an extension, no scaling is done
and data is returned as a 1-D vector. The user can use the IDL
function REFORM to convert the data to the correct dimensions
if desired. If /DATA_ONLY is specified, no scaling is done.
HEADER - FITS Header. The STScI inheritance convention is recognized
http://fits.gsfc.nasa.gov/registry/inherit/fits_inheritance.txt
If an extension is read, and the INHERIT keyword exists with a
value of T, and the /NO_PDU keyword keyword is not supplied,
then the primary data unit header and the extension header will
be combined. The header will have the form:
BEGIN MAIN HEADER --------------------------------
BEGIN EXTENSION HEADER ---------------------------
1. (Default=0, the first group)
OUTPUT KEYWORD PARAMETERS:
ENUM - Output extension number that was read.
MESSAGE = value: Output error message
NOTES:
Determination or which extension to read.
case 1: EXTEN_NO specified. EXTEN_NO will give the number of the
extension to read. The primary data unit is refered
to as extension 0. If EXTEN_NO is specified, XTENSION,
EXTNAME, EXTVER, and EXTLEVEL parameters are ignored.
case 2: if EXTEN_NO is not specified, the first extension
with the specified XTENSION, EXTNAME, EXTVER, and
EXTLEVEL will be read. If any of the 4 parameters
are not specified, they will not be used in the search.
Setting EXTLEVEL=0, EXTVER=0, EXTNAME='', or
XTENSION='' is the same as not supplying them.
case 3: if none of the keyword parameters, EXTEN_NO, XTENSION,
EXTNAME, EXTVER, or EXTLEVEL are supplied. FITS_READ
will read the next extension in the file. If the
primary data unit (PDU), extension 0, is null, the
first call to FITS_READ will read the first extension
of the file.
The only way to read a null PDU is to use EXTEN_NO = 0.
If FIRST and LAST are specified, the data is returned without applying
any scale factors (BSCALE and BZERO) and the data is returned in a
1-D vector. This will allow you to read any portion of a multiple
dimension data set. Once returned, the IDL function REFORM can be
used to place the correct dimensions on the data.
IMPLICIT IMAGES: FITS_READ will construct an implicit image
for cases where NAXIS=0 and the NPIX1, NPIX2, and PIXVALUE
keywords are present. The output image will be:
image = replicate(PIXVALUE,NPIX1,NPIX2)
FPACK compressed files are always closed and reopened when exiting
FITS_READ so that the pointer is set to the beginning of the file. (Since
FPACK files are opened with a bidirectional pipe rather than OPEN, one
cannot use POINT_LUN to move to a specified position in the file.)
EXAMPLES:
Read the primary data unit of a FITS file, if it is null read the
first extension:
FITS_READ, 'myfile.fits', data, header
Read the first two extensions of a FITS file and the extension with
EXTNAME = 'FLUX' and EXTVER = 4
FITS_OPEN, 'myfile.fits', fcb
FITS_READ, fcb,data1, header2, exten_no = 1
FITS_READ, fcb,data1, header2, exten_no = 2
FITS_READ, fcb,data3, header3, extname='flux', extver=4
FITS_CLOSE, fcb
Read the sixth image in a data cube for the fourth extension.
FITS_OPEN, 'myfile.fits', fcb
image_number = 6
ns = fcb.axis(0,4)
nl = fcb.axis(1,4)
i1 = (ns*nl)*(image_number-1)
i2 = i2 + ns*nl-1
FITS_READ,fcb,image,header,first=i1,last=i2
image = reform(image,ns,nl,/overwrite)
FITS_CLOSE
PROCEDURES USED:
FITS_CLOSE, FITS_OPEN
SXADDPAR, SXDELPAR, SXPAR()
WARNINGS:
In Sep 2006, FITS_OPEN was modified to open FITS files using the
/SWAP_IF_LITTLE_ENDIAN keyword to OPEN, so that subsequent routines
(FITS_READ, FITS_WRITE) did not require any byte swapping. An error
may result if an pre-Sep 2006 version of FITS_OPEN is used with a
post Sep 2006 version of FITS_READ, FITS_WRITE or MODFITS.
HISTORY:
Written by: D. Lindler, August 1995
Avoid use of !ERR W. Landsman August 1999
Read unsigned datatypes, added /no_unsigned W. Landsman December 1999
Don't call FITS_CLOSE unless fcb is defined W. Landsman January 2000
Set BZERO = 0 for unsigned integer data W. Landsman January 2000
Only call IEEE_TO_HOST if needed W. Landsman February 2000
Ensure EXTEND keyword in primary header W. Landsman April 2001
Don't erase ERROR message when closing file W. Landsman April 2002
Assume at least V5.1 remove NANValue keyword W. Landsman November 2002
Work with compress files (read file size from fcb),
requires updated (Jan 2003) version of FITS_OPEN W. Landsman Jan 2003
Do not modify BSCALE/BZERO for unsigned integers W. Landsman April 2006
Asuume FITS_OPEN has opened the file with /SWAP_IF_LITTLE_ENDIAN
W. Landsman September 2006
Fix problem with /DATA_ONLY keyword M.Buie/W.Landsman October 2006
Only append primary header if INHERIT=T W. Landsman April 2007
Make ndata 64bit for very large files E. Hivon/W. Landsman May 2007
Added /PDU keyword to always append primary header W. Landsman June 2007
Use PRODUCT to compute # of data points W. Landsman May 2009
Make sure FIRST is long64 when computing position W.L. October 2009
Read FPACK compressed files, W.L. December 2010
Don't assume FCB has a FCOMPRESS tag W.L./Satori UeNO September 2012
(See astrolib/pro/fits_read.pro)
FITS_TEST_CHECKSUM()
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NAME:
FITS_TEST_CHECKSUM()
PURPOSE:
Verify the values of the CHECKSUM and DATASUM keywords in a FITS header
EXPLANATION:
Follows the 2007 version of the FITS checksum proposal at
http://fits.gsfc.nasa.gov/registry/checksum.html
CALLING SEQUENCE:
result = FITS_TEST_CHECKSUM(HDR, [ DATA, ERRMSG=, /FROM_IEEE ])
INPUTS:
HDR - FITS header (vector string)
OPTIONAL DATA:
DATA - data array associated with the FITS header. If not supplied, or
set to a scalar, then there is assumed to be no data array
associated with the FITS header.
RESULT:
An integer -1, 0 or 1 indicating the following conditions:
1 - CHECKSUM (and DATASUM) keywords are present with correct values
0 - CHECKSUM keyword is not present
-1 - CHECKSUM or DATASUM keyword does not have the correct value
indicating possible data corruption.
OPTIONAL INPUT KEYWORD:
/FROM_IEEE - If this keyword is set, then the input is assumed to be in
big endian format (e.g. an untranslated FITS array). This
keyword only has an effect on little endian machines (e.g.
a Linux box).
OPTIONAL OUTPUT KEYWORD:
ERRMSG - will contain a scalar string giving the error condition. If
RESULT = 1 then ERRMSG will be an empty string. If this
output keyword is not supplied, then the error message will be
printed at the terminal.
NOTES:
The header and data must be *exactly* as originally written in the FITS
file. By default, some FITS readers may alter keyword values (e.g.
BSCALE) or append information (e.g. HISTORY or an inherited primary
header) and this will alter the checksum value.
PROCEDURES USED:
CHECKSUM32, FITS_ASCII_ENCODE(), SXPAR()
EXAMPLE:
Verify the CHECKSUM keywords in the primary header/data unit of a FITS
file 'test.fits'
FITS_READ,'test.fits',data,hdr,/no_PDU,/NoSCALE
print,FITS_TEST_CHECKSUM(hdr,data)
Note the use of the /No_PDU and /NoSCALE keywords to avoid any alteration
of the FITS header
REVISION HISTORY:
W. Landsman SSAI December 2002
Return quietly if CHECKSUM keywords not found W. Landsman May 2003
Add /NOSAVE to CHECKSUM32 calls when possible W. Landsman Sep 2004
(See astrolib/pro/fits_test_checksum.pro)
FITS_WRITE
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NAME:
FITS_WRITE
PURPOSE:
To write a FITS primary data unit or extension.
EXPLANATION:
***NOTE** This version of FITS_READ must be used with a post Sep 2006
version of FITS_OPEN.
CALLING SEQUENCE:
FITS_WRITE, filename_or_fcb, data, [header_in]
INPUTS:
FILENAME_OR_FCB: name of the output data file or the FITS control
block returned by FITS_OPEN (called with the /WRITE or
/APPEND) parameters.
OPTIONAL INPUTS:
DATA: data array to write. If not supplied or set to a scalar, a
null image is written.
HEADER_IN: FITS header keyword. If not supplied, a minimal basic
header will be created. Required FITS keywords, SIMPLE,
BITPIX, XTENSION, NAXIS, ... are added by FITS_WRITE and
do not need to be supplied with the header. If supplied,
their values will be updated as necessary to reflect DATA.
INPUT KEYWORD PARAMETERS:
XTENSION: type of extension to write (Default="IMAGE"). If not
supplied, it will be taken from HEADER_IN. If not in either
place, the default is "IMAGE". This parameter is ignored
when writing the primary data unit. Note that binary and
and ASCII table extensions already have a properly formatted
header (e.g. with TTYPE* keywords) and byte array data.
EXTNAME: EXTNAME for the extension. If not supplied, it will be taken
from HEADER_IN. If not supplied and not in HEADER_IN, no
EXTNAME will be written into the output extension.
EXTVER: EXTVER for the extension. If not supplied, it will be taken
from HEADER_IN. If not supplied and not in HEADER_IN, no
EXTVER will be written into the output extension.
EXTLEVEL: EXTLEVEL for the extension. If not supplied, it will be taken
from HEADER_IN. If not supplied and not in HEADER_IN, no
EXTLEVEL will be written into the output extension.
/NO_ABORT: Set to return to calling program instead of a RETALL
when an I/O error is encountered. If set, the routine will
return a non-null string (containing the error message) in the
keyword MESSAGE. If /NO_ABORT not set, then FITS_WRITE will
print the message and issue a RETALL
/NO_DATA: Set if you only want FITS_WRITE to write a header. The
header supplied will be written without modification and
the user is expected to write the data using WRITEU to unit
FCB.UNIT. When FITS_WRITE is called with /NO_DATA, the user is
responsible for the validity of the header, and must write
the correct amount and format of the data. When FITS_WRITE
is used in this fashion, it will pad the data from a previously
written extension to 2880 blocks before writting the header.
OUTPUT KEYWORD PARAMETERS:
MESSAGE: value of the error message for use with /NO_ABORT
HEADER: actual output header written to the FITS file.
NOTES:
If the first call to FITS_WRITE is an extension, FITS_WRITE will
automatically write a null image as the primary data unit.
Keywords and history in the input header will be properly separated
into the primary data unit and extension portions when constructing
the output header (See FITS_READ for information on the internal
Header format which separates the extension and PDU header portions).
EXAMPLES:
Write an IDL variable to a FITS file with the minimal required header.
FITS_WRITE,'newfile.fits',ARRAY
Write the same array as an image extension, with a null Primary data
unit.
FITS_WRITE,'newfile.fits',ARRAY,xtension='IMAGE'
Write 4 additional image extensions to the same file.
FITS_OPEN,'newfile.fits',fcb
FITS_WRITE,fcb,data1,extname='FLUX',extver=1
FITS_WRITE,fcb,err1,extname'ERR',extver=1
FITS_WRITE,fcb,data2,extname='FLUX',extver=2
FITS_WRITE,fcb,err2,extname='ERR',extver=2
FITS_CLOSE,FCB
WARNING:
FITS_WRITE currently does not completely update the file control block.
When mixing FITS_READ and FITS_WRITE commands it is safer to use
file names, rather than passing the file control block.
PROCEDURES USED:
FITS_OPEN, SXADDPAR, SXDELPAR, SXPAR()
HISTORY:
Written by: D. Lindler August, 1995
Work for variable length extensions W. Landsman August 1997
Converted to IDL V5.0 W. Landsman September 1997
PCOUNT and GCOUNT added for IMAGE extensions J. Graham October 1999
Write unsigned data types W. Landsman December 1999
Pad data area with zeros not blanks W. McCann/W. Landsman October 2000
Return Message='' to signal normal operation W. Landsman Nov. 2000
Ensure that required extension table keywords are in proper order
W.V. Dixon/W. Landsman March 2001
Assume since V5.1, remove NaNValue keyword W. Landsman Nov. 2002
Removed obsolete !ERR system variable W. Landsman Feb 2004
Check that byte array supplied with table extension W. Landsman Mar 2004
Make number of bytes 64bit to avoid possible overflow W.L Apr 2006
Asuume FITS_OPEN has opened the file with /SWAP_IF_LITTLE_ENDIAN
W. Landsman September 2006
Removes BZERO and BSCALE for floating point output, D. Lindler, Sep 2008
(See astrolib/pro/fits_write.pro)
FLEGENDRE
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NAME:
FLEGENDRE
PURPOSE:
Compute the first M terms in a Legendre polynomial expansion.
EXPLANATION:
Meant to be used as a supplied function to SVDFIT.
This procedure became partially obsolete in IDL V5.0 with the
introduction of the /LEGENDRE keyword to SVDFIT and the associated
SVDLEG function. However, note that, unlike SVDLEG, FLEGENDRE works
on vector values of X.
CALLING SEQUENCE:
result = FLEGENDRE( X, M)
INPUTS:
X - the value of the independent variable, scalar or vector
M - number of term of the Legendre expansion to compute, integer scalar
OUTPUTS:
result - (N,M) array, where N is the number of elements in X and M
is the order. Contains the value of each Legendre term for
each value of X
EXAMPLE:
(1) If x = 2.88 and M = 3 then
IDL> print, flegendre(x,3) ==> [1.00, 2.88, 11.9416]
This result can be checked by explicitly computing the first 3 Legendre
terms, 1.0, x, 0.5*( 3*x^2 -1)
(2) Find the coefficients to an M term Legendre polynomial that gives
the best least-squares fit to a dataset (x,y)
IDL> coeff = SVDFIT( x,y,M,func='flegendre')
The coefficients can then be supplied to the function POLYLEG to
compute the best YFIT values for any X.
METHOD:
The recurrence relation for the Legendre polynomials is used to compute
each term. Compare with the function FLEG in "Numerical Recipes"
by Press et al. (1992), p. 674
REVISION HISTORY:
Written Wayne Landsman Hughes STX April 1995
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/flegendre.pro)
FLUX2MAG
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NAME:
FLUX2MAG
PURPOSE:
Convert from flux (ergs/s/cm^2/A) to magnitudes.
EXPLANATION:
Use MAG2FLUX() for the opposite direction.
CALLING SEQUENCE:
mag = flux2mag( flux, [ zero_pt, ABwave= ] )
INPUTS:
flux - scalar or vector flux vector, in erg cm-2 s-1 A-1
OPTIONAL INPUT:
zero_pt - scalar giving the zero point level of the magnitude.
If not supplied then zero_pt = 21.1 (Code et al 1976)
Ignored if the ABwave keyword is supplied
OPTIONAL KEYWORD INPUT:
ABwave - wavelength scalar or vector in Angstroms. If supplied, then
FLUX2MAG() returns Oke AB magnitudes (Oke & Gunn 1983, ApJ, 266,
713).
OUTPUT:
mag - magnitude vector. If the ABwave keyword is set then mag
is given by the expression
ABMAG = -2.5*alog10(f) - 5*alog10(ABwave) - 2.406
Otherwise, mag is given by the expression
mag = -2.5*alog10(flux) - zero_pt
EXAMPLE:
Suppose one is given wavelength and flux vectors, w (in Angstroms) and
f (in erg cm-2 s-1 A-1). Plot the spectrum in AB magnitudes
IDL> plot, w, flux2mag(f,ABwave = w), /nozero
REVISION HISTORY:
Written J. Hill STX Co. 1988
Converted to IDL V5.0 W. Landsman September 1997
Added ABwave keyword W. Landsman September 1998
(See astrolib/pro/flux2mag.pro)
FM_UNRED
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NAME:
FM_UNRED
PURPOSE:
Deredden a flux vector using the Fitzpatrick (1999) parameterization
EXPLANATION:
The R-dependent Galactic extinction curve is that of Fitzpatrick & Massa
(Fitzpatrick, 1999, PASP, 111, 63; astro-ph/9809387 ).
Parameterization is valid from the IR to the far-UV (3.5 microns to 0.1
microns). UV extinction curve is extrapolated down to 912 Angstroms.
CALLING SEQUENCE:
FM_UNRED, wave, flux, ebv, [ funred, R_V = , /LMC2, /AVGLMC, ExtCurve=
gamma =, x0=, c1=, c2=, c3=, c4= ]
INPUT:
WAVE - wavelength vector (Angstroms)
FLUX - calibrated flux vector, same number of elements as WAVE
If only 3 parameters are supplied, then this vector will
updated on output to contain the dereddened flux.
EBV - color excess E(B-V), scalar. If a negative EBV is supplied,
then fluxes will be reddened rather than dereddened.
OUTPUT:
FUNRED - unreddened flux vector, same units and number of elements
as FLUX
OPTIONAL INPUT KEYWORDS
R_V - scalar specifying the ratio of total to selective extinction
R(V) = A(V) / E(B - V). If not specified, then R = 3.1
Extreme values of R(V) range from 2.3 to 5.3
/AVGLMC - if set, then the default fit parameters c1,c2,c3,c4,gamma,x0
are set to the average values determined for reddening in the
general Large Magellanic Cloud (LMC) field by Misselt et al.
(1999, ApJ, 515, 128)
/LMC2 - if set, then the fit parameters are set to the values determined
for the LMC2 field (including 30 Dor) by Misselt et al.
Note that neither /AVGLMC or /LMC2 will alter the default value
of R_V which is poorly known for the LMC.
The following five input keyword parameters allow the user to customize
the adopted extinction curve. For example, see Clayton et al. (2003,
ApJ, 588, 871) for examples of these parameters in different interstellar
environments.
x0 - Centroid of 2200 A bump in microns (default = 4.596)
gamma - Width of 2200 A bump in microns (default =0.99)
c3 - Strength of the 2200 A bump (default = 3.23)
c4 - FUV curvature (default = 0.41)
c2 - Slope of the linear UV extinction component
(default = -0.824 + 4.717/R)
c1 - Intercept of the linear UV extinction component
(default = 2.030 - 3.007*c2
OPTIONAL OUTPUT KEYWORD:
ExtCurve - Returns the E(wave-V)/E(B-V) extinction curve, interpolated
onto the input wavelength vector
EXAMPLE:
Determine how a flat spectrum (in wavelength) between 1200 A and 3200 A
is altered by a reddening of E(B-V) = 0.1. Assume an "average"
reddening for the diffuse interstellar medium (R(V) = 3.1)
IDL> w = 1200 + findgen(40)*50 ;Create a wavelength vector
IDL> f = w*0 + 1 ;Create a "flat" flux vector
IDL> fm_unred, w, f, -0.1, fnew ;Redden (negative E(B-V)) flux vector
IDL> plot,w,fnew
NOTES:
(1) The following comparisons between the FM curve and that of Cardelli,
Clayton, & Mathis (1989), (see ccm_unred.pro):
(a) - In the UV, the FM and CCM curves are similar for R < 4.0, but
diverge for larger R
(b) - In the optical region, the FM more closely matches the
monochromatic extinction, especially near the R band.
(2) Many sightlines with peculiar ultraviolet interstellar extinction
can be represented with the FM curve, if the proper value of
R(V) is supplied.
(3) Use the 4 parameter calling sequence if you wish to save the
original flux vector.
PROCEDURE CALLS:
CSPLINE(), POLY()
REVISION HISTORY:
Written W. Landsman Raytheon STX October, 1998
Based on FMRCurve by E. Fitzpatrick (Villanova)
Added /LMC2 and /AVGLMC keywords, W. Landsman August 2000
Added ExtCurve keyword, J. Wm. Parker August 2000
Assume since V5.4 use COMPLEMENT to WHERE W. Landsman April 2006
(See astrolib/pro/fm_unred.pro)
FORPRINT
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NAME:
FORPRINT
PURPOSE:
Print a set of vectors by looping over each index value.
EXPLANATION:
If W and F are equal length vectors, then the statement
IDL> forprint, w, f
is equivalent to
IDL> for i = 0L, N_elements(w)-1 do print,w[i],f[i]
CALLING SEQUENCE:
forprint, v1,[ v2, v3, v4,....v18, FORMAT = , TEXTOUT = ,STARTLINE =,
SUBSET=, NUMLINE =, /SILENT, COMMENT= ]
INPUTS:
V1,V2,...V18 - Arbitary IDL vectors. If the vectors are not of
equal length then the number of rows printed will be equal
to the length of the smallest vector. Up to 18 vectors
can be supplied.
OPTIONAL KEYWORD INPUTS:
TEXTOUT - Controls print output device, defaults to !TEXTOUT
textout=1 TERMINAL using /more option if available
textout=2 TERMINAL without /more option
textout=3 file 'forprint.prt'
textout=4 file 'laser.tmp'
textout=5 user must open file
textout = filename (default extension of .prt)
textout=7 Append to .prt file if it exists
COMMENT - String scalar or vector to write to the first line of output
file if TEXTOUT > 2. By default, FORPRINT will write a time
stamp on the first line. Use /NOCOMMENT if you don't want
FORPRINT to write anything in the output file. If COMMENT
is a vector then one line will be written for each element.
FORMAT - Scalar format string as in the PRINT procedure. The use
of outer parenthesis is optional. Ex. - format="(F10.3,I7)"
This program will automatically remove a leading "$" from
incoming format statements. Ex. - "$(I4)" would become "(I4)".
If omitted, then IDL default formats are used.
/NOCOMMENT - Set this keyword if you don't want any comment line
line written as the first line in a harcopy output file.
/SILENT - Normally, with a hardcopy output (TEXTOUT > 2), FORPRINT will
print an informational message. If the SILENT keyword
is set and non-zero, then this message is suppressed.
SUBSET - Index vector specifying elements to print. No error checking
is done to make sure the indicies are valid. The statement
IDL> forprint,x,y,z,subset=s
is equivalent to
IDL> for i=0,n-1 do print, x[s[i]], y[s[i]], z[s[i]]
STARTLINE - Integer scalar specifying the first line in the arrays
to print. Default is STARTLINE = 1, i.e. start at the
beginning of the arrays. (If a SUBSET keyword is supplied
then STARTLINE refers to first element in the subscript vector.)
/STDOUT - If set, the force standard output unit (=-1) if not writing
to a file. This allows the FORPINT output to be captured
in a journal file. Only needed for non-GUI terminals
WIDTH - Line width for wrapping, passed onto OPENW when using hardcopy.
OUTPUTS:
None
SYSTEM VARIABLES:
If keyword TEXTOUT is not used, the default is the nonstandard
keyword !TEXTOUT. If you want to use FORPRINT to write more than
once to the same file then set TEXTOUT=5, and open and close the
file yourself (see documentation of TEXTOPEN for more info).
The non-standard system variables !TEXTOUT and !TEXTUNIT are
automatically added if not present to start with.
EXAMPLE:
Suppose W,F, and E are the wavelength, flux, and epsilon vectors for
a spectrum. Print these values to a file 'output.dat' in a nice
format.
IDL> fmt = '(F10.3,1PE12.2,I7)'
IDL> forprint, F = fmt, w, f, e, TEXT = 'output.dat'
RESTRICTIONS:
Uses the EXECUTE() function and so is not compatible with the IDL
virtual machine.
PROCEDURES CALLED:
TEXTOPEN, TEXTCLOSE
REVISION HISTORY:
Written W. Landsman April, 1989
Keywords textout and format added, J. Isensee, July, 1990
Made use of parenthesis in FORMAT optional W. Landsman May 1992
Added STARTLINE keyword W. Landsman November 1992
Set up so can handle 18 input vectors. J. Isensee, HSTX Corp. July 1993
Handle string value of TEXTOUT W. Landsman, HSTX September 1993
Added NUMLINE keyword W. Landsman, HSTX February 1996
Added SILENT keyword W. Landsman, RSTX, April 1998
Much faster printing to a file W. Landsman, RITSS, August, 2001
Use SIZE(/TNAME) instead of DATATYPE() W. Landsman SSAI October 2001
Fix skipping of first line bug introduced Aug 2001 W. Landsman Nov2001
Added /NOCOMMENT keyword, the SILENT keyword now controls only
the display of informational messages. W. Landsman June 2002
Skip PRINTF if IDL in demo mode W. Landsman October 2004
Assume since V5.4 use BREAK instead of GOTO W. Landsman April 2006
Add SUBSET keyword, warning if different size vectors passed.
P.Broos,W.Landsman. Aug 2006
Change keyword_set() to N_elements W. Landsman Oct 2006
Added /STDOUT keyword W. Landsman Oct 2006
Fix error message for undefined variable W. Landsman April 2007
Added WIDTH keyword J. Bailin Nov 2010
Allow multiple (vector) comment lines W. Landsman April 2011
Define !TEXTOUT and !TEXTUNIT if needed. W. Landsman October 2012
(See astrolib/pro/forprint.pro)
FREBIN
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NAME:
FREBIN
PURPOSE:
Shrink or expand the size of an array an arbitary amount using interpolation
EXPLANATION:
FREBIN is an alternative to CONGRID or REBIN. Like CONGRID it
allows expansion or contraction by an arbitary amount. ( REBIN requires
integral factors of the original image size.) Like REBIN it conserves
flux by ensuring that each input pixel is equally represented in the output
array.
CALLING SEQUENCE:
result = FREBIN( image, nsout, nlout, [ /TOTAL] )
INPUTS:
image - input image, 1-d or 2-d numeric array
nsout - number of samples in the output image, numeric scalar
OPTIONAL INPUT:
nlout - number of lines in the output image, numeric scalar
If not supplied, then set equal to 1
OPTIONAL KEYWORD INPUTS:
/total - if set, the output pixels will be the sum of pixels within
the appropriate box of the input image. Otherwise they will
be the average. Use of the /TOTAL keyword conserves surface flux.
OUTPUTS:
The resized image is returned as the function result. If the input
image is of type DOUBLE or FLOAT then the resized image is of the same
type. If the input image is BYTE, INTEGER or LONG then the output
image is usually of type FLOAT. The one exception is expansion by
integral amount (pixel duplication), when the output image is the same
type as the input image.
EXAMPLE:
Suppose one has an 800 x 800 image array, im, that must be expanded to
a size 850 x 900 while conserving surface flux:
IDL> im1 = frebin(im,850,900,/total)
im1 will be a 850 x 900 array, and total(im1) = total(im)
NOTES:
If the input image sizes are a multiple of the output image sizes
then FREBIN is equivalent to the IDL REBIN function for compression,
and simple pixel duplication on expansion.
If the number of output pixels are not integers, the output image
size will be truncated to an integer. The platescale, however, will
reflect the non-integer number of pixels. For example, if you want to
bin a 100 x 100 integer image such that each output pixel is 3.1
input pixels in each direction use:
n = 100/3.1 ; 32.2581
image_out = frebin(image,n,n)
The output image will be 32 x 32 and a small portion at the trailing
edges of the input image will be ignored.
PROCEDURE CALLS:
None.
HISTORY:
Adapted from May 1998 STIS version, written D. Lindler, ACC
Added /NOZERO, use INTERPOLATE instead of CONGRID, June 98 W. Landsman
Fixed for nsout non-integral but a multiple of image size Aug 98 D.Lindler
DJL, Oct 20, 1998, Modified to work for floating point image sizes when
expanding the image.
Improve speed by addressing arrays in memory order W.Landsman Dec/Jan 2001
(See astrolib/pro/frebin.pro)
FTAB_DELROW
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NAME:
FTAB_DELROW
PURPOSE:
Delete rows of data from a FITS ASCII or binary table extension
CALLING SEQUENCE:
ftab_delrow, filename, rows, EXTEN_NO =, NEWFILE = ]
INPUTS-OUPUTS
filename - scalar string giving name of the FITS file containing an
ASCII or binary table extension.
rows - scalar or vector, specifying the row numbers to delete
First row has index 0. If a vector, it will be sorted and
duplicates will be removed
OPTIONAL KEYWORD INPUTS:
EXTEN_NO - scalar integer specifying which extension number to process
Default is to process the first extension
NEWFILE - scalar string specifying the name of the new output FITS file
FTAB_DELROW will prompt for this parameter if not supplied
EXAMPLE:
Compress the first extension of a FITS file 'test.fits' to include
only non-negative values in the 'FLUX' column
ftab_ext,'test.fits','flux',flux ;Obtain original flux vector
bad = where(flux lt 0) ;Find negative fluxes
ftab_delrow,'test.fits',bad,new='test1.fits' ;Delete specified rows
RESTRICTIONS:
Does not work for variable length binary tables
PROCEDURES USED:
FITS_CLOSE, FITS_OPEN, FITS_READ, FITS_WRITE, FTDELROW, TBDELROW
REVISION HISTORY:
Written W. Landsman STX Co. August, 1997
Converted to IDL V5.0 W. Landsman September 1997
Use COPY_LUN if V5.6 or later W. Landsman February 2003
Assume since V5.6, COPY_LUN available W. Landsman Sep 2006
(See astrolib/pro/ftab_delrow.pro)
FTAB_EXT
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NAME:
FTAB_EXT
PURPOSE:
Routine to extract columns from a FITS (binary or ASCII) table.
CALLING SEQUENCE:
FTAB_EXT, name_or_fcb, columns, v1, [v2,..,v9, ROWS=, EXTEN_NO= ]
INPUTS:
name_or_fcb - either a scalar string giving the name of a FITS file
containing a (binary or ASCII) table, or an IDL structure
containing as file control block (FCB) returned by FITS_OPEN
If FTAB_EXT is to be called repeatedly on the same file, then
it is quicker to first open the file with FITS_OPEN, and then
pass the FCB structure to FTAB_EXT
columns - table columns to extract. Can be either
(1) String with names separated by commas
(2) Scalar or vector of column numbers
OUTPUTS:
v1,...,v30 - values for the columns. Up to 30 columns can be extracted
OPTIONAL INPUT KEYWORDS:
ROWS - scalar or vector giving row number(s) to extract
Row numbers start at 0. If not supplied or set to
-1 then values for all rows are returned
EXTEN_NO - Extension number to process. If not set, then data is
extracted from the first extension in the file (EXTEN_NO=1)
EXAMPLES:
Read wavelength and flux vectors from the first extension of a
FITS file, 'spec.fit'. Using FTAB_HELP,'spec.fit' we find that this
information is in columns named 'WAVELENGTH' and 'FLUX' (in columns 1
and 2). To read the data
IDL> ftab_ext,'spec.fit','wavelength,flux',w,f
or
IDL> ftab_ext,'spec.fit',[1,2],w,f
PROCEDURES CALLED:
FITS_READ, FITS_CLOSE, FTINFO, FTGET(), TBINFO, TBGET()
HISTORY:
version 1 W. Landsman August 1997
Converted to IDL V5.0 W. Landsman September 1997
Improve speed processing binary tables W. Landsman March 2000
Use new FTINFO calling sequence W. Landsman May 2000
Don't call fits_close if fcb supplied W. Landsman May 2001
Use STRSPLIT to parse column string W. Landsman July 2002
Cleanup pointers in TBINFO structure W. Landsman November 2003
Avoid EXECUTE() if V6.1 or later W. Landsamn December 2006
Assume since V6.1 W. Landsman June 2009
Read up to 30 columns W.L. Aug 2009
(See astrolib/pro/ftab_ext.pro)
FTAB_HELP
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NAME:
FTAB_HELP
PURPOSE:
Describe the columns of a FITS binary or ASCII table extension(s).
CALLING SEQUENCE:
FTAB_HELP, filename, [ EXTEN_No = , TEXTOUT= ]
or
FTAB_HELP, fcb, [EXTEN_No=, TEXTOUT= ]
INPUTS:
filename - scalar string giving name of the FITS file.
fcb - FITS control block returned by a previous call to FITS_OPEN
OPTIONAL KEYWORD INPUTS:
EXTEN_NO - integer scalar or vector specifying which FITS extensions
to display. Default is to display all FITS extension.
TEXTOUT - scalar number (0-7) or string (file name) determining
output device (see TEXTOPEN). Default is TEXTOUT=1, output
to the user's terminal
EXAMPLE:
Describe the columns in the second and fourth extensions of a FITS
file spec.fits and write the results to a file 'spec24.lis'
IDL> ftab_help,'spec.fits',exten=[2,4],t='spec24.lis'
SYSTEM VARIABLES:
Uses the non-standard system variables !TEXTOUT and !TEXTUNIT
which must be defined (e.g. with ASTROLIB) before compilation
NOTES:
The behavior of FTAB_HELP was changed in August 2005 to display
all extensions by default, rather than just the first extension
PROCEDURES USED:
FITS_READ, FITS_CLOSE, FITS_OPEN, FTHELP, TBHELP, TEXTOPEN, TEXTCLOSE
HISTORY:
version 1 W. Landsman August 1997
Corrected documentation W. Landsman September 1997
Don't call fits_close if fcb supplied W. Landsman May 2001
Default now is to display all extensions, EXTEN keyword can now
be a vector W. Landsman Aug 2005
(See astrolib/pro/ftab_help.pro)
FTAB_PRINT
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NAME:
FTAB_PRINT
PURPOSE:
Print the contents of a FITS (binary or ASCII) table extension.
EXPLANATION:
User can specify which rows or columns to print
CALLING SEQUENCE:
FTAB_PRINT, filename, columns, rows,
[ TEXTOUT=, FMT=, EXTEN_NO= NUM_HEADER_LINES ]
INPUTS:
filename - scalar string giving name of a FITS file containing a
binary or ASCII table
columns - string giving column names, or vector giving
column numbers (beginning with 1). If a string
supplied then column names should be separated by comma's.
if not supplied, then all columns are printed.
If set to '*' then all columns are printed in table format
(1 row per line, binary tables only).
rows - (optional) vector of row numbers to print (beginning with 0).
If not supplied or set to scalar, -1, then all rows
are printed.
OPTIONAL KEYWORD INPUT:
EXTEN_NO - Extension number to read. If not set, then the first
extension is printed (EXTEN_NO=1)
FMT = Format string for print display (binary tables only). If not
supplied, then any formats in the TDISP keyword fields will be
used, otherwise IDL default formats. For ASCII tables, the
format used is always as stored in the FITS table.
NUM_HEADER_LINES - Number of lines to display the column headers (default
= 1). By setting NUM_HEADER_LINES to an integer larger than 1,
one can avoid truncation of the headers. In addition, setting
NUM_HEADER_LINES will display commented lines indicating
a FORMAT for reading the data, and a suggested call to
readfmt.pro. Works for binary tables only
NVAL_PER_LINE - The maximum number of values displayed from a
multivalued column when printing in table format. Default = 6
TEXTOUT - scalar number (0-7) or string (file name) determining
output device (see TEXTOPEN). Default is TEXTOUT=1, output
to the user's terminal
EXAMPLE:
(1) Print all rows of the first 5 columns of the first extension of the
file 'wfpc.fits'
IDL> ftab_print,'vizier.fits',indgen(5)+1
(2) Print all columns of the first row to a file 'vizier.dat' in
'table' format
IDL> ftab_print,'vizier.fits',t='vizier.dat','*',0
SYSTEM VARIABLES:
Uses the non-standard system variables !TEXTOUT and !TEXTUNIT
which must be defined (e.g. with ASTROLIB) prior to compilation.
PROCEDURES USED:
FITS_CLOSE, FITS_OPEN, FITS_READ, FTPRINT, TBPRINT
HISTORY:
version 1 W. Landsman August 1997
Check whether data exists W. Landsman Feb 2007
Check whether extension exists W. Landsman Mar 2010
Added NUM_HEADER_LINES, NVAL_PER_LINE keywords for binary tables
W. Landsman Apr 2010
(See astrolib/pro/ftab_print.pro)
FTADDCOL
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NAME:
FTADDCOL
PURPOSE:
Routine to add a field to a FITS ASCII table
CALLING SEQUENCE:
ftaddcol, h, tab, name, idltype, [ tform, tunit, tscal, tzero, tnull ]
INPUTS:
h - FITS table header. It will be updated as appropriate
tab - FITS table array. Number of columns will be increased if
neccessary.
name - field name, scalar string
idltype - idl data type (as returned by SIZE function) for field,
For string data (type=7) use minus the string length.
OPTIONAL INPUTS:
tform - format specification 'qww.dd' where q = A, I, E, or D
tunit - string giving physical units for the column.
tscal - scale factor
tzero - zero point for field
tnull - null value for field
Use '' as the value of tform,tunit,tscal,tzero,tnull if you want
the default or no specification of them in the table header.
OUTPUTS:
h,tab - updated to allow new column of data
PROCEDURES USED:
FTINFO, FTSIZE, GETTOK(), SXADDPAR
HISTORY:
version 1 D. Lindler July, 1987
Converted to IDL V5.0 W. Landsman September 1997
Updated call to new FTINFO W. Landsman April 2000
(See astrolib/pro/ftaddcol.pro)
FTCREATE
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NAME:
FTCREATE
PURPOSE:
Create a new (blank) FITS ASCII table and header with specified size.
CALLING SEQUENCE:
ftcreate, maxcols, maxrows, h, tab
INPUTS:
maxcols - number of character columns allocated, integer scalar
maxrows - maximum number of rows allocated, integer scalar
OUTPUTS:
h - minimal FITS Table extension header, string array
OPTIONAL OUTPUT:
tab - empty table, byte array
HISTORY:
version 1 D. Lindler July. 87
Converted to IDL V5.0 W. Landsman September 1997
Make table creation optional, allow 1 row table, add comments to
required FITS keywords W. Landsman October 2001
(See astrolib/pro/ftcreate.pro)
FTDELCOL
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NAME:
FTDELCOL
PURPOSE:
Delete a column of data from a FITS table
CALLING SEQUENCE:
ftdelcol, h, tab, name
INPUTS-OUPUTS
h,tab - FITS table header and data array. H and TAB will
be updated with the specified column deleted
INPUTS:
name - Either (1) a string giving the name of the column to delete
or (2) a scalar giving the column number to delete
EXAMPLE:
Suppose it has been determined that the F7.2 format used for a field
FLUX in a FITS table is insufficient. The old column must first be
deleted before a new column can be written with a new format.
flux = FTGET(h,tab,'FLUX') ;Save the existing values
FTDELCOL,h,tab,'FLUX' ;Delete the existing column
FTADDCOL,h,tab,'FLUX',8,'F9.2' ;Create a new column with larger format
FTPUT,h,tab,'FLUX',0,flux ;Put back the original values
REVISION HISTORY:
Written W. Landsman STX Co. August, 1988
Adapted for IDL Version 2, J. Isensee, July, 1990
Converted to IDL V5.0 W. Landsman September 1997
Updated call to new FTINFO W. Landsman May 2000
(See astrolib/pro/ftdelcol.pro)
FTDELROW
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NAME:
FTDELROW
PURPOSE:
Delete a row of data from a FITS table
CALLING SEQUENCE:
ftdelrow, h, tab, rows
INPUTS-OUPUTS
h,tab - FITS table header and data array. H and TAB will
be updated on output with the specified row(s) deleted.
rows - scalar or vector, specifying the row numbers to delete
This vector will be sorted and duplicates removed by FTDELROW
EXAMPLE:
Compress a table to include only non-negative flux values
flux = FTGET(h,tab,'FLUX') ;Obtain original flux vector
bad = where(flux lt 0) ;Find negative fluxes
FTDELROW,h,tab,bad ;Delete rows with negative fluxes
PROCEDURE:
Specified rows are deleted from the data array, TAB. The NAXIS2
keyword in the header is updated.
PROCEDURES USED:
sxaddpar
REVISION HISTORY:
Written W. Landsman STX Co. August, 1988
Checked for IDL Version 2, J. Isensee, July, 1990
Converted to IDL V5.0 W. Landsman September 1997
Assume since V5.4, use BREAK instead of GOTO W. Landsman April 2006
(See astrolib/pro/ftdelrow.pro)
FTGET
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NAME:
FTGET
PURPOSE:
Function to return value(s) from specified column in a FITS ASCII table
CALLING SEQUENCE
values = FTGET( h, tab, field, [ rows, nulls ] )
or
values = FTGET( ft_str, tab, field. [rows, nulls]
INPUTS:
h - FITS ASCII extension header (e.g. as returned by FITS_READ)
or
ft_str - FITS table structure extracted from FITS header by FTINFO
Use of the IDL structure will improve processing speed
tab - FITS ASCII table array (e.g. as returned by FITS_READ)
field - field name or number
OPTIONAL INPUTS:
rows - scalar or vector giving row number(s)
Row numbers start at 0. If not supplied or set to
-1 then values for all rows are returned
OUTPUTS:
the values for the row are returned as the function value.
Null values are set to 0 or blanks for strings.
OPTIONAL OUTPUT:
nulls - null value flag of same length as the returned data.
It is set to 1 at null value positions and 0 elsewhere.
If supplied then the optional input, rows, must also
be supplied.
EXAMPLE:
Read the columns labeled 'WAVELENGTH' and 'FLUX' from the second
(ASCII table) extension of a FITS file 'spectra.fit'
IDL> fits_read,'spectra.fit',tab,htab,exten=2 ;Read 2nd extension
IDL> w = ftget( htab, tab,'wavelength') ;Wavelength vector
IDL> f = ftget( htab, tab,'flux') ;Flux vector
Slightly more efficient would be to first call FTINFO
IDL> ftinfo, htab, ft_str ;Extract structure
IDL> w = ftget(ft_str, tab,'wavelength') ;Wavelength vector
IDL> f = ftget(ft_str, tab,'flux') ;Flux vector
NOTES:
(1) Use the higher-level procedure FTAB_EXT to extract vectors
directly from the FITS file.
(2) Use FTAB_HELP or FTHELP to determine the columns in a particular
ASCII table.
HISTORY:
coded by D. Lindler July, 1987
Always check for null values W. Landsman August 1990
More informative error message W. Landsman Feb. 1996
Converted to IDL V5.0 W. Landsman September 1997
Allow structure rather than FITS header W. Landsman May 2000
No case sensitivity in TTYPE name W. Landsman February 2002
(See astrolib/pro/ftget.pro)
FTHELP
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NAME:
FTHELP
PURPOSE:
Routine to print a description of a FITS ASCII table extension
CALLING SEQUENCE:
FTHELP, H, [ TEXTOUT = ]
INPUTS:
H - FITS header for ASCII table extension, string array
OPTIONAL INPUT KEYWORD
TEXTOUT - scalar number (0-7) or string (file name) determining
output device (see TEXTOPEN). Default is TEXTOUT=1, output
to the user's terminal
NOTES:
FTHELP checks that the keyword XTENSION equals 'TABLE' in the FITS
header.
SYSTEM VARIABLES:
Uses the non-standard system variables !TEXTOUT and !TEXTUNIT
which must be defined (e.g. with ASTROLIB) prior to compilation.
PROCEDURES USED:
REMCHAR, SXPAR(), TEXTOPEN, TEXTCLOSE, ZPARCHECK
HISTORY:
version 1 W. Landsman Jan. 1988
Add TEXTOUT option, cleaner format W. Landsman September 1991
TTYPE value can be longer than 8 chars, W. Landsman August 1995
Remove calls to !ERR, some vectorization W. Landsman February 2000
Slightly more compact display W. Landsman August 2005
(See astrolib/pro/fthelp.pro)
FTHMOD
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NAME:
FTHMOD
PURPOSE:
Procedure to modify header information for a specified field
in a FITS table.
CALLING SEQUENCE:
fthmod, h, field, parameter, value
INPUT:
h - FITS header for the table
field - field name or number
parameter - string name of the parameter to modify. Choices
include:
TTYPE - field name
TUNIT - physical units for field (eg. 'ANGSTROMS')
TNULL - null value (string) for field, (eg. '***')
TFORM - format specification for the field
TSCAL - scale factor
TZERO - zero offset
User should be aware that the validity of the change is
not checked. Unless you really know what you are doing,
this routine should only be used to change field names,
units, or another user specified parameter.
value - new value for the parameter. Refer to the FITS table
standards documentation for valid values.
EXAMPLE:
Change the units for a field name "FLUX" to "Janskys" in a FITS table
header,h
IDL> FTHMOD, h, 'FLUX', 'TUNIT','Janskys'
METHOD:
The header keyword is modified
with the new value.
HISTORY:
version 1, D. Lindler July 1987
Converted to IDL V5.0 W. Landsman September 1997
Major rewrite to use new FTINFO call W. Landsman May 2000
(See astrolib/pro/fthmod.pro)
FTINFO
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NAME:
FTINFO
PURPOSE:
Return an informational structure from a FITS ASCII table header.
CALLING SEQUENCE:
ftinfo,h,ft_str, [Count = ]
INPUTS:
h - FITS ASCII table header, string array
OUTPUTS:
ft_str - IDL structure with extracted info from the FITS ASCII table
header. Tags include
.tbcol - starting column position in bytes
.width - width of the field in bytes
.idltype - idltype of field.
7 - string, 4- real*4, 3-integer, 5-real*8
.tunit - string unit numbers
.tscal - scale factor
.tzero - zero point for field
.tnull - null value for the field
.tform - format for the field
.ttype - field name
OPTIONAL OUTPUT KEYWORD:
Count - Integer scalar giving number of fields in the table
PROCEDURES USED:
GETTOK(), SXPAR()
NOTES:
This procedure underwent a major revision in May 2000, and **THE
NEW CALLING SEQUENCE IS INCOMPATIBLE WITH THE OLD ONE **
HISTORY:
D. Lindler July, 1987
Converted to IDL V5.0 W. Landsman September 1997
Major rewrite, return structure W. Landsman April 2000
(See astrolib/pro/ftinfo.pro)
FTKEEPROW
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NAME:
FTKEEPROW
PURPOSE:
Subscripts (and reorders) a FITS table. A companion piece to FTDELROW.
CALLING SEQUENCE:
ftkeeprow, h, tab, subs
INPUT PARAMETERS:
h = FITS table header array
tab = FITS table data array
subs = subscript array of FITS table rows. Works like any other IDL
subscript array (0 based, of course).
OUTPUT PARAMETERS:
h and tab are modified
MODIFICATION HISTORY:
Written by R. S. Hill, ST Sys. Corp., 2 May 1991.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/ftkeeprow.pro)
FTPRINT
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NAME:
FTPRINT
PURPOSE:
Procedure to print specified columns and rows of a FITS table
CALLING SEQUENCE:
FTPRINT, h, tab, columns, [ rows, TEXTOUT = ]
INPUTS:
h - Fits header for table, string array
tab - table array
columns - string giving column names, or vector giving
column numbers (beginning with 1). If string
supplied then column names should be separated by comma's.
rows - (optional) vector of row numbers to print. If
not supplied or set to scalar, -1, then all rows
are printed.
OUTPUTS:
None
OPTIONAL INPUT KEYWORDS:
TEXTOUT controls the output device; see the procedure TEXTOPEN
SYSTEM VARIABLES:
Uses nonstandard system variables !TEXTOUT and !TEXTOPEN
These will be defined (using ASTROLIB) if not already present.
Set !TEXTOUT = 3 to direct output to a disk file. The system
variable is overriden by the value of the keyword TEXTOUT
EXAMPLES:
ftprint,h,tab,'STAR ID,RA,DEC' ;print id,ra,dec for all stars
ftprint,h,tab,[2,3,4],indgen(100) ;print columns 2-4 for
;first 100 stars
ftprint,h,tab,text="stars.dat" ;Convert entire FITS table to
;an ASCII file named STARS.DAT
PROCEDURES USED:
FTSIZE, FTINFO, TEXTOPEN, TEXTCLOSE
RESTRICTIONS:
(1) Program does not check whether output length exceeds output
device capacity (e.g. 80 or 132).
(2) Column heading may be truncated to fit in space defined by
the FORMAT specified for the column
(3) Program does not check for null values
HISTORY:
version 1 D. Lindler Feb. 1987
Accept undefined values of rows, columns W. Landsman August 1997
New FTINFO calling sequence W. Landsman May 2000
Parse scalar string with STRSPLIT W. Landsman July 2002
Fix format display of row number W. Landsman March 2003
Fix format display of row number again W. Landsman May 2003
(See astrolib/pro/ftprint.pro)
FTPUT
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NAME:
FTPUT
PURPOSE:
Procedure to add or update a field in an FITS ASCII table
CALLING SEQUENCE:
FTPUT, htab, tab, field, row, values, [ nulls ]
INPUTS:
htab - FITS ASCII table header string array
tab - FITS ASCII table array (e.g. as read by READFITS)
field - string field name or integer field number
row - either a non-negative integer scalar giving starting row to
update, or a non-negative integer vector specifying rows to
update. FTPUT will append a new row to a table if the value
of 'row' exceeds the number of rows in the tab array
values - value(s) to add or update. If row is a vector
then values must contain the same number of elements.
OPTIONAL INPUT:
nulls - null value flag of same length as values.
It should be set to 1 at null value positions
and 0 elsewhere.
OUTPUTS:
htab,tab will be updated as specified.
EXAMPLE:
One has a NAME and RA and Dec vectors for 500 stars with formats A6,
F9.5 and F9.5 respectively. Write this information to an ASCII table
named 'star.fits'.
IDL> FTCREATE,24,500,h,tab ;Create table header and (empty) data
IDL> FTADDCOL,h,tab,'RA',8,'F9.5','DEGREES' ;Explicity define the
IDL> FTADDCOL,h,tab,'DEC',8,'F9.5','DEGREES' ;RA and Dec columns
IDL> FTPUT,h,tab,'RA',0,ra ;Insert RA vector into table
IDL> FTPUT,h,tab,'DEC',0,dec ;Insert DEC vector into table
IDL> FTPUT, h,tab, 'NAME',0,name ;Insert NAME vector with default
IDL> WRITEFITS,'stars.fits',tab,h ;Write to a file
Note that (1) explicit formatting has been supplied for the (numeric)
RA and Dec vectors, but was not needed for the NAME vector, (2) A width
of 24 was supplied in FTCREATE based on the expected formats (6+9+9),
though the FT* will adjust this value as necessary, and (3) WRITEFITS
will create a minimal primary header
NOTES:
(1) If the specified field is not already in the table, then FTPUT will
create a new column for that field using default formatting. However,
FTADDCOL should be called prior to FTPUT for explicit formatting.
PROCEDURES CALLED
FTADDCOL, FTINFO, FTSIZE, SXADDPAR, SXPAR()
HISTORY:
version 1 D. Lindler July, 1987
Allow E format W. Landsman March 1992
Write in F format if E format will overflow April 1994
Update documentation W. Landsman January 1996
Allow 1 element vector W. Landsman March 1996
Adjust string length to maximum of input string array June 1997
Work for more than 32767 elements August 1997
Converted to IDL V5.0 W. Landsman September 1997
Updated call to the new FTINFO W. Landsman May 2000
Fix case where header does not have any columns yet W.Landsman Sep 2002
Assume since V5.2, omit fstring() call W. Landsman April 2006
(See astrolib/pro/ftput.pro)
FTSIZE
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NAME:
FTSIZE
PURPOSE:
Procedure to return the size of a FITS ASCII table.
CALLING SEQUENCE:
ftsize,h,tab,ncols,rows,tfields,ncols_all,nrows_all, [ERRMSG = ]
INPUTS:
h - FITS ASCII table header, string array
tab - FITS table array, 2-d byte array
OUTPUTS:
ncols - number of characters per row in table
nrows - number of rows in table
tfields - number of fields per row
ncols_all - number of characters/row allocated (size of tab)
nrows_all - number of rows allocated
OPTIONAL OUTPUT KEYWORD:
ERRMSG = If this keyword is present, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned.
HISTORY
D. Lindler July, 1987
Fix for 1-row table, W. Landsman HSTX, June 1994
Converted to IDL V5.0 W. Landsman September 1997
Added ERRMSG keyword W. Landsman May 2000
(See astrolib/pro/ftsize.pro)
FTSORT
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NAME:
FTSORT
PURPOSE:
Sort a FITS ASCII table according to a specified field
CALLING SEQUENCE:
FTSORT,h,tab,[field, REVERSE = ] ;Sort original table header and array
or
FTSORT,h,tab,hnew,tabnew,[field, REVERSE =] ;Create new sorted header
INPUTS:
H - FITS header (string array)
TAB - FITS table (byte array) associated with H. If less than 4
parameters are supplied, then H and TAB will be updated to
contain the sorted table
OPTIONAL INPUTS:
FIELD - Field name(s) or number(s) used to sort the entire table.
If FIELD is a vector then the first element is used for the
primary sort, the second element is used for the secondary
sort, and so forth. (A secondary sort only takes effect when
values in the primary sort field are equal.) Character fields
are sorted using the ASCII collating sequence. If omitted,
the user will be prompted for the field name.
OPTIONAL OUTPUTS:
HNEW,TABNEW - Header and table containing the sorted tables
EXAMPLE:
Sort a FITS ASCII table by the 'DECLINATION' field in descending order
Assume that the table header htab, and array, tab, have already been
read (e.g. with READFITS or FITS_READ):
IDL> FTSORT, htab, tab,'DECLINATION',/REVERSE
OPTIONAL INPUT KEYWORD:
REVERSE - If set then the table is sorted in reverse order (maximum
to minimum. If FIELD is a vector, then REVERSE can also be
a vector. For example, REVERSE = [1,0] indicates that the
primary sort should be in descending order, and the secondary
sort should be in ascending order.
EXAMPLE:
SIDE EFFECTS:
A HISTORY record is added to the table header.
REVISION HISTORY:
Written W. Landsman June, 1988
Converted to IDL V5.0 W. Landsman September 1997
New FTINFO calling sequence, added REVERSE keyword, allow secondary sorts
W. Landsman May 2000
(See astrolib/pro/ftsort.pro)
FXADDPAR
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NAME:
FXADDPAR
Purpose :
Add or modify a parameter in a FITS header array.
Explanation :
This version of FXADDPAR will write string values longer than 68
characters using the FITS continuation convention described at
http://heasarc.gsfc.nasa.gov/docs/heasarc/ofwg/docs/ofwg_recomm/r13.html
Use :
FXADDPAR, HEADER, NAME, VALUE, COMMENT
Inputs :
HEADER = String array containing FITS header. The maximum string
length must be equal to 80. If not defined, then FXADDPAR
will create an empty FITS header array.
NAME = Name of parameter. If NAME is already in the header the
value and possibly comment fields are modified. Otherwise a
new record is added to the header. If NAME is equal to
either "COMMENT" or "HISTORY" then the value will be added to
the record without replacement. In this case the comment
parameter is ignored.
VALUE = Value for parameter. The value expression must be of the
correct type, e.g. integer, floating or string.
String values of 'T' or 'F' are considered logical
values unless the /NOLOGICAL keyword is set. If the value is
a string and is "long" (more than 69 characters), then it
may be continued over more than one line using the OGIP
CONTINUE standard.
Opt. Inputs :
COMMENT = String field. The '/' is added by this routine. Added
starting in position 31. If not supplied, or set equal to ''
(the null string), then any previous comment field in the
header for that keyword is retained (when found).
Outputs :
HEADER = Updated header array.
Opt. Outputs:
None.
Keywords :
BEFORE = Keyword string name. The parameter will be placed before the
location of this keyword. For example, if BEFORE='HISTORY'
then the parameter will be placed before the first history
location. This applies only when adding a new keyword;
keywords already in the header are kept in the same position.
AFTER = Same as BEFORE, but the parameter will be placed after the
location of this keyword. This keyword takes precedence over
BEFORE.
FORMAT = Specifies FORTRAN-like format for parameter, e.g. "F7.3". A
scalar string should be used. For complex numbers the format
should be defined so that it can be applied separately to the
real and imaginary parts. If not supplied, then the IDL
default formatting is used, except that double precision is
given a format of G19.12.
/NOCONTINUE = By default, FXADDPAR will break strings longer than 68
characters into multiple lines using the continuation
convention. If this keyword is set, then the line will
instead be truncated to 68 characters. This was the default
behaviour of FXADDPAR prior to December 1999.
/NOLOGICAL = If set, then the values 'T' and 'F' are not interpreted as
logical values, and are simply added without interpretation.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL, e.g.
ERRMSG = ''
FXADDPAR, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
DETABIFY(), FXPAR(), FXPARPOS()
Common :
None.
Restrictions:
Warning -- Parameters and names are not checked against valid FITS
parameter names, values and types.
The required FITS keywords SIMPLE (or XTENSION), BITPIX, NAXIS, NAXIS1,
NAXIS2, etc., must be entered in order. The actual values of these
keywords are not checked for legality and consistency, however.
Side effects:
All HISTORY records are inserted in order at the end of the header.
All COMMENT records are also inserted in order at the end of the
header, but before the HISTORY records. The BEFORE and AFTER keywords
can override this.
All records with no keyword (blank) are inserted in order at the end of
the header, but before the COMMENT and HISTORY records. The BEFORE and
AFTER keywords can override this.
All other records are inserted before any of the HISTORY, COMMENT, or
"blank" records. The BEFORE and AFTER keywords can override this.
String values longer than 68 characters will be split into multiple
lines using the OGIP CONTINUE convention, unless the /NOCONTINUE keyword
is set. For a description of the CONTINUE convention see
http://fits.gsfc.nasa.gov/registry/continue_keyword.html
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Jan 1992, from SXADDPAR by D. Lindler and J. Isensee.
Differences include:
* LOCATION parameter replaced with keywords BEFORE and AFTER.
* Support for COMMENT and "blank" FITS keywords.
* Better support for standard FITS formatting of string and
complex values.
* Built-in knowledge of the proper position of required
keywords in FITS (although not necessarily SDAS/Geis) primary
headers, and in TABLE and BINTABLE extension headers.
William Thompson, May 1992, fixed bug when extending length of header,
and new record is COMMENT, HISTORY, or blank.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 5 September 1997
Fixed bug replacing strings that contain "/" character--it
interpreted the following characters as a comment.
Version 3, Craig Markwardt, GSFC, December 1997
Allow long values to extend over multiple lines
Version 4, D. Lindler, March 2000, modified to use capital E instead
of a lower case e for exponential format.
Version 4.1 W. Landsman April 2000, make user-supplied format uppercase
Version 4.2 W. Landsman July 2002, positioning of EXTEND keyword
Version 5, 23-April-2007, William Thompson, GSFC
Version 6, 02-Aug-2007, WTT, bug fix for OGIP long lines
Version 6.1, 10-Feb-2009, W. Landsman, increase default format precision
Version 6.2 30-Sep-2009, W. Landsman, added /NOLOGICAL keyword
Version :
Version 6.2, 30-Sep-2009
(See astrolib/pro/fxaddpar.pro)
FXBADDCOL
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NAME:
FXBADDCOL
PURPOSE :
Adds a column to a binary table extension.
EXPLANATION :
Modify a basic FITS binary table extension (BINTABLE) header array to
define a column.
USE :
FXBADDCOL, INDEX, HEADER, ARRAY [, TTYPE [, COMMENT ]]
INPUTS :
HEADER = String array containing FITS extension header.
ARRAY = IDL variable used to determine the data size and type
associated with the column. If the column is defined as
containing variable length arrays, then ARRAY must be of the
maximum size to be stored in the column.
Opt. Inputs :
TTYPE = Column label.
COMMENT = Comment for TTYPE
Outputs :
INDEX = Index (1-999) of the created column.
HEADER = The header is modified to reflect the added column.
Opt. Outputs:
None.
Keywords :
VARIABLE= If set, then the column is defined to contain pointers to
variable length arrays in the heap area.
DCOMPLEX= If set, and ARRAY is complex, with the first dimension being
two (real and imaginary parts), then the column is defined as
double-precision complex (type "M"). This keyword is
only needed prior to IDL Version 4.0, when the double
double complex datatype was unavailable in IDL
BIT = If passed, and ARRAY is of type byte, then the column is
defined as containg bit mask arrays (type "X"), with the
value of BIT being equal to the number of mask bits.
LOGICAL = If set, and array is of type byte, then the column is defined
as containing logical arrays (type "L").
NO_TDIM = If set, then the TDIMn keyword is not written out to the
header. No TDIMn keywords are written for columns containing
variable length arrays.
TUNIT = If passed, then corresponding keyword is added to header.
TSCAL = Same.
TZERO = Same.
TNULL = Same.
TDISP = Same.
TDMIN = Same.
TDMAX = Same.
TDESC = Same.
TCUNI = Same.
TROTA = Same.
TRPIX = Same.
TRVAL = Same.
TDELT = Same.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBADDCOL, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
FXADDPAR, FXPAR
Common :
None.
Restrictions:
Warning: No checking is done of any of the parameters defining the
values of optional FITS keywords.
FXBHMAKE must first be called to initialize the header.
If ARRAY is of type character, then it must be of the maximum length
expected for this column. If a character string array, then the
largest string in the array is used to determine the maximum length.
The DCOMPLEX keyword is ignored if ARRAY is not double-precision.
ARRAY must also have a first dimension of two representing the real and
imaginary parts.
The BIT and LOGICAL keywords are ignored if ARRAY is not of type byte.
BIT takes precedence over LOGICAL.
Side effects:
If the data array is multidimensional, then a TDIM keyword is added to
the header, unless either NO_TDIM or VARIABLE is set.
No TDIMn keywords are written out for bit arrays (format 'X'), since
the dimensions would refer to bits, not bytes.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Jan 1992.
W. Thompson, Feb 1992, changed from function to procedure.
W. Thompson, Feb 1992, modified to support variable length arrays.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 31 May 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 4, William Thompson, GSFC, 30 December 1994
Added keyword TCUNI.
Version 5, Wayne Landsman, GSFC, 12 Aug 1997
Recognize double complex IDL datatype
Version 6, Wayne Landsman, GSFC. C. Yamauchi (ISAS) 23 Feb 2006
Support 64bit integers
Version 7, C. Markwardt, GSFC, Allow unsigned integers, which
have special TSCAL/TZERO values. Feb 2009
Version 8, P.Broos (PSU), Wayne Landsman (GSFC) Mar 2010
Do *not* force TTYPE* keyword to uppercase
Version :
Version 8, Mar 2010
(See astrolib/pro/fxbaddcol.pro)
FXBCLOSE
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NAME:
FXBCLOSE
Purpose :
Close a FITS binary table extension opened for read.
Explanation :
Closes a FITS binary table extension that had been opened for read by
FXBOPEN.
Use :
FXBCLOSE, UNIT
Inputs :
UNIT = Logical unit number of the file.
Opt. Inputs :
None.
Outputs :
None.
Opt. Outputs:
None.
Keywords :
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBCLOSE, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
None.
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The file must have been opened with FXBOPEN.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Feb. 1992.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 June 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version :
Version 3, 23 June 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbclose.pro)
FXBCOLNUM()
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NAME:
FXBCOLNUM()
Purpose :
Returns a binary table column number.
Explanation :
Given a column specified either by number or name, this routine will
return the appropriate column number.
Use :
Result = FXBCOLNUM( UNIT, COL )
Inputs :
UNIT = Logical unit number corresponding to the file containing the
binary table.
COL = Column in the binary table, given either as a character
string containing a column label (TTYPE), or as a numerical
column index starting from column one.
Opt. Inputs :
None.
Outputs :
The result of the function is the number of the column specified, or
zero if no column is found (when passed by name).
Opt. Outputs:
None.
Keywords :
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
Result = FXBCOLNUM( ERRMSG=ERRMSG, ... )
IF ERRMSG NE '' THEN ...
Calls :
None.
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The binary table file must have been opened with FXBOPEN.
If COL is passed as a number, rather than as a name, then it must be
consistent with the number of columns in the table.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
None.
Written :
William Thompson, GSFC, 2 July 1993.
Modified :
Version 1, William Thompson, GSFC, 2 July 1993.
Version 2, William Thompson, GSFC, 29 October 1993.
Added error message for not finding column by name.
Version 3, William Thompson, GSFC, 21 June 1994
Added ERRMSG keyword.
Version 4, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version :
Version 4, 23 June 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbcolnum.pro)
FXBCREATE
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NAME:
FXBCREATE
Purpose :
Open a new binary table at the end of a FITS file.
Explanation :
Write a binary table extension header to the end of a disk FITS file,
and leave it open to receive the data.
The FITS file is opened, and the pointer is positioned just after the
last 2880 byte record. Then the binary header is appended. Calls to
FXBWRITE will append the binary data to this file, and then FXBFINISH
will close the file.
Use :
FXBCREATE, UNIT, FILENAME, HEADER
Inputs :
FILENAME = Name of FITS file to be opened.
HEADER = String array containing the FITS binary table extension
header.
Opt. Inputs :
None.
Outputs :
UNIT = Logical unit number of the opened file.
EXTENSION= Extension number of newly created extension.
Opt. Outputs:
None.
Keywords :
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBCREATE, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
FXADDPAR, FXBFINDLUN, FXBPARSE, FXFINDEND
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The primary FITS data unit must already be written to a file. The
binary table extension header must already be defined (FXBHMAKE), and
must match the data that will be written to the file.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Jan 1992, based on WRITEFITS by J. Woffard and W. Landsman.
W. Thompson, Feb 1992, changed from function to procedure.
W. Thompson, Feb 1992, removed all references to temporary files.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 July 1993.
Fixed bug with variable length arrays.
Version 3, William Thompson, GSFC, 21 June 1994
Added ERRMSG keyword.
Version 4, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 5, Antony Bird, Southampton, 25 June 1997
Modified to allow very long tables
Version :
Version 5, 25 June 1997
Converted to IDL V5.0 W. Landsman September 1997
Added EXTENSION parameter, C. Markwardt 1999 Jul 15
More efficient zeroing of file, C. Markwardt, 26 Feb 2001
Recompute header size if updating THEAP keyword B. Roukema April 2010
(See astrolib/pro/fxbcreate.pro)
FXBDIMEN()
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NAME:
FXBDIMEN()
PURPOSE:
Returns the dimensions for a column in a FITS binary table.
Explanation : This procedure returns the dimensions associated with a column
in a binary table opened for read with the command FXBOPEN.
Use : Result = FXBDIMEN(UNIT,COL)
Inputs : UNIT = Logical unit number returned by FXBOPEN routine.
Must be a scalar integer.
COL = Column in the binary table to read data from, either
as a character string containing a column label
(TTYPE), or as a numerical column index starting from
column one.
Opt. Inputs : None.
Outputs : The result of the function is an array containing the
dimensions for the specified column in the FITS binary table
that UNIT points to.
Opt. Outputs: None.
Keywords : ERRMSG = If defined and passed, then any error messages will
be returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no
errors are encountered, then a null string is
returned. In order to use this feature, ERRMSG must
be defined first, e.g.
ERRMSG = ''
Result = FXBDIMEN( ERRMSG=ERRMSG, ... )
IF ERRMSG NE '' THEN ...
Calls : FXBCOLNUM, FXBFINDLUN
Common : Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions: None.
Side effects: The dimensions will be returned whether or not the table is
still open or not.
If UNIT does not point to a binary table, then 0 is returned.
If UNIT is an undefined variable, then 0 is returned.
Category : Data Handling, I/O, FITS, Generic.
Prev. Hist. : None.
Written : William Thompson, GSFC, 4 March 1994.
Modified : Version 1, William Thompson, GSFC, 4 March 1994.
Version 2, William Thompson, GSFC, 21 June 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version : Version 3, 23 June 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbdimen.pro)
FXBFIND
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NAME:
FXBFIND
Purpose :
Find column keywords in a FITS binary table header.
Explanation :
Finds the value of a column keyword for all the columns in the binary
table for which it is set. For example,
FXBFIND, UNIT, 'TTYPE', COLUMNS, VALUES, N_FOUND
Would find all instances of the keywords TTYPE1, TTYPE2, etc. The
array COLUMNS would contain the column numbers for which a TTYPEn
keyword was found, and VALUES would contain the values. N_FOUND would
contain the total number of instances found.
Use :
FXBFIND, [UNIT or HEADER], KEYWORD, COLUMNS, VALUES, N_FOUND
[, DEFAULT ]
Inputs :
Either UNIT or HEADER must be passed.
UNIT = Logical unit number of file opened by FXBOPEN.
HEADER = FITS binary table header.
KEYWORD = Prefix to a series of FITS binary table column keywords. The
keywords to be searched for are formed by combining this
prefix with the numbers 1 through the value of TFIELDS in the
header.
Opt. Inputs :
DEFAULT = Default value to use for any column keywords that aren't
found. If passed, then COLUMNS and VALUES will contain
entries for every column. Otherwise, COLUMNS and VALUES only
contain entries for columns where values were found.
Outputs :
COLUMNS = Array containing the column numbers for which values of the
requested keyword series were found.
VALUES = Array containing the found values.
N_FOUND = Number of values found. The value of this parameter is
unaffected by whether or not DEFAULT is passed.
Opt. Outputs:
None.
Output Keywords :
COMMENTS = Comments associated with each keyword, if any
Calls :
FXBFINDLUN, FXPAR
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
If UNIT is passed, then the file must have been opened with FXBOPEN.
If HEADER is passed, then it must be a legal FITS binary table header.
The type of DEFAULT must be consistent with the values of the requested
keywords, i.e. both most be either of string or numerical type.
The KEYWORD prefix must not have more than five characters to leave
room for the three digits allowed for the column numbers.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Feb. 1992.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Vectorized implementation improves performance, CM 18 Nov 1999
Added COMMENTS keyword CM Nov 2003
Remove use of obsolete !ERR system variable W. Landsman April 2010
Fix error introduced April 2010 W. Landsman
Version :
Version 3, April 2010.
(See astrolib/pro/fxbfind.pro)
FXBFINDLUN()
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NAME:
FXBFINDLUN()
Purpose :
Find logical unit number UNIT in FXBINTABLE common block.
Explanation :
Finds the proper index to use for getting information about the logical
unit number UNIT in the arrays stored in the FXBINTABLE common block.
Called from FXBCREATE and FXBOPEN.
Use :
Result = FXBFINDLUN( UNIT )
Inputs :
UNIT = Logical unit number.
Opt. Inputs :
None.
Outputs :
The result of the function is an index into the FXBINTABLE common
block.
Opt. Outputs:
None.
Keywords :
None.
Calls :
None.
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
None.
Side effects:
If UNIT is not found in the common block, then it is added to the
common block.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Feb. 1992.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 July 1993.
Added DHEAP variable to fix bug with variable length arrays.
Version 3, Michael Schubnell, University of Michigan, 22 May 1996
Change N_DIMS from short to long integer.
Version :
Version 3, 22 May 1996
Converted to IDL V5.0 W. Landsman September 1997
Make NAXIS1, NAXIS2, HEAP, DHEAP, BYTOFF 64-bit integers to deal with large files,
E. Hivon Mar 2008
(See astrolib/pro/fxbfindlun.pro)
FXBFINISH
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NAME:
FXBFINISH
Purpose :
Close a FITS binary table extension file opened for write.
Explanation :
Closes a FITS binary table extension file that had been opened for
write by FXBCREATE.
Use :
FXBFINISH, UNIT
Inputs :
UNIT = Logical unit number of the file.
Opt. Inputs :
None.
Outputs :
None.
Opt. Outputs:
None.
Keywords :
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBFINISH, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
None.
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The file must have been opened with FXBCREATE, and written with
FXBWRITE.
Side effects:
Any bytes needed to pad the file out to an integral multiple of 2880
bytes are written out to the file. Then, the file is closed.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Jan 1992.
W. Thompson, Feb 1992, modified to support variable length arrays.
W. Thompson, Feb 1992, removed all references to temporary files.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 July 1993.
Fixed bug with variable length arrays.
Version 3, William Thompson, GSFC, 31 May 1994
Added ERRMSG keyword.
Version 4, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version :
Version 4, 23 June 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbfinish.pro)
FXBGROW
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NAME:
FXBGROW
PURPOSE :
Increase the number of rows in a binary table.
EXPLANATION :
Call FXBGROW to increase the size of an already-existing FITS
binary table. The number of rows increases to NROWS; however
the table cannot shrink by this operation. This procedure is
useful when a table with an unknown number of rows must be
created. The caller would then call FXBCREATE to construct a
table of some base size, and follow with calls to FXBGROW to
lengthen the table as needed. The extension being enlarged
need not be the last extension in the file. If subsequent
extensions exist in the file, they will be shifted properly.
CALLING SEQUENCE :
FXBGROW, UNIT, HEADER, NROWS[, ERRMSG= , NOZERO= , BUFFERSIZE= ]
INPUT PARAMETERS :
UNIT = Logical unit number of an already-opened file.
HEADER = String array containing the FITS binary table extension
header. The header is modified in place.
NROWS = New number of rows, always more than the previous
number.
OPTIONAL INPUT KEYWORDS:
NOZERO = when set, FXBGROW will not zero-pad the new data if
it doesn't have to.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBGROW, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
BUFFERSIZE = Size in bytes for intermediate data transfers
(default 32768)
Calls :
FXADDPAR, FXHREAD, BLKSHIFT
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The file must be open with write permission.
The binary table extension in question must already by written
to the file (using FXBCREATE).
A table can never shrink via this operation.
SIDE EFFECTS:
The FITS file will grow in size, and heap areas are
preserved by moving them to the end of the file.
The header is modified to reflect the new number of rows.
CATEGORY :
Data Handling, I/O, FITS, Generic.
Initially written, C. Markwardt, GSFC, Nov 1998
Added ability to enlarge arbitrary extensions and tables with
variable sized rows, not just the last extension in a file,
CM, April 2000
Fix bug in the zeroing of the output file, C. Markwardt, April 2005
(See astrolib/pro/fxbgrow.pro)
FXBHEADER()
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NAME:
FXBHEADER()
PURPOSE:
Returns the header of an open FITS binary table.
EXPLANATION:
This procedure returns the FITS extension header of a FITS
binary table opened for read with the command FXBOPEN.
Use : Result = FXBHEADER(UNIT)
Inputs : UNIT = Logical unit number returned by FXBOPEN routine.
Must be a scalar integer.
Opt. Inputs : None.
Outputs : The result of the function is a string array containing the
header for the FITS binary table that UNIT points to.
Opt. Outputs: None.
Keywords : None.
Calls : FXBFINDLUN
Common : Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions: None.
Side effects: The string array returned always has as many elements as the
largest header read by FXBOPEN. Any extra elements beyond the
true header are blank or null strings.
The header will be returned whether or not the table is still
open or not.
If UNIT does not point to a binary table, then a string array
of nulls is returned.
If UNIT is an undefined variable, then the null string is
returned.
Category : Data Handling, I/O, FITS, Generic.
Prev. Hist. : None.
Written : William Thompson, GSFC, 1 July 1993.
Modified : Version 1, William Thompson, GSFC, 1 July 1993.
Version : Version 1, 1 July 1993.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbheader.pro)
FXBHELP
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NAME:
FXBHELP
Purpose :
Prints short description of columns in a FITS binary table.
Explanation :
Prints a short description of the columns in a FITS binary table to the
terminal screen.
Use :
FXBHELP, UNIT
Inputs :
UNIT = Logical unit number of file opened by FXBOPEN.
Opt. Inputs :
None.
Outputs :
None.
Opt. Outputs:
None.
Keywords :
None.
Calls :
FXBFIND, FXBFINDLUN, FXPAR
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The file must have been opened with FXBOPEN.
Side effects:
Certain fields may be truncated in the display.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Feb. 1992, from TBHELP by W. Landsman.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 12 May 1993.
Modified to not write to a logical unit number assigned to the
terminal. This makes it compatible with IDL for Windows.
Version 3, Wayne Landsman GSFC April 2010
Remove use of obsolete !ERR system variable
Version :
Version 3, April 2010.
(See astrolib/pro/fxbhelp.pro)
FXBHMAKE
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NAME:
FXBHMAKE
Purpose :
Create basic FITS binary table extension (BINTABLE) header.
Explanation :
Creates a basic header array with all the required keywords, but with
none of the table columns defined. This defines a basic structure
which can then be added to or modified by other routines.
Use :
FXBHMAKE, HEADER, NROWS [, EXTNAME [, COMMENT ]]
Inputs :
NROWS = Number of rows in the binary table.
Opt. Inputs :
EXTNAME = If passed, then the EXTNAME record is added with this value.
COMMENT = Comment to go along with EXTNAME.
Outputs :
HEADER = String array containing FITS extension header.
Opt. Outputs:
None.
Keywords :
INITIALIZE = If set, then the header is completely initialized, and any
previous entries are lost.
DATE = If set, then the DATE keyword is added to the header.
EXTVER = Extension version number (integer).
EXTLEVEL = Extension level number (integer).
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBHMAKE, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
GET_DATE, FXADDPAR, FXHCLEAN
Common :
None.
Restrictions:
Warning: No checking is done of any of the parameters.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Jan 1992.
William Thompson, Sep 1992, added EXTVER and EXTLEVEL keywords.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 June 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version :
Version 3, 23 June 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbhmake.pro)
FXBINTABLE
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NAME:
FXBINTABLE
Purpose :
Common block FXBINTABLE used by "FXB" routines.
Explanation :
This is not an IDL routine as such, but contains the definition of the
common block FXBINTABLE for inclusion into other routines. By defining
the common block in one place, the problem of conflicting definitions
is avoided.
This file is included into routines that need this common block with
the single line (left justified)
@fxbintable
FXBINTABLE contains the following arrays:
LUN = An array of logical unit numbers of currently (or
previously) opened binary table files.
STATE = Array containing the state of the FITS files
associated with the logical unit numbers, where
0=closed, 1=open for read, and 2=open for write.
HEAD = FITS binary table headers.
MHEADER = Array containing the positions of the first data byte
of the header for each file referenced by array LUN.
NHEADER = Array containing the positions of the first data byte
after the header for each file referenced by array
LUN.
NAXIS1 = Values of NAXIS1 from the binary table headers.
NAXIS2 = Values of NAXIS2 from the binary table headers.
TFIELDS = Values of TFIELDS from the binary table headers.
HEAP = The start of the first byte of the heap area
for variable length arrays.
DHEAP = The start of the first byte of the next variable
length array, if writing.
BYTOFF = Byte offset from the beginning of the row for each
column in the binary table headers.
TTYPE = Values of TTYPE for each column in the binary table
headers.
FORMAT = Character code formats of the various columns.
IDLTYPE = IDL type code for each column in the binary table
headers.
N_ELEM = Number of elements for each column in the binary
table headers.
TSCAL = Scale factors for the individual columns.
TZERO = Zero offsets for the individual columns.
MAXVAL = For variable length arrays, contains the maximum
number of elements for each column in the binary
table headers.
N_DIMS = Number of dimensions, and array of dimensions for
each column of type string in the binary table
headers.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Feb 1992.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 July 1993.
Added DHEAP variable to fix bug with variable length arrays.
Version :
Version 2, 21 July 1993.
(See astrolib/pro/fxbintable.pro)
FXBISOPEN()
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NAME:
FXBISOPEN()
PURPOSE:
Returns true if UNIT points to an open FITS binary table.
Explanation : This procedure checks to see if the logical unit number given
by the variable UNIT corresponds to a FITS binary table opened
for read with the command FXBOPEN, and which has not yet been
closed with FXBCLOSE.
Use : Result = FXBISOPEN(UNIT)
If FXBISOPEN(UNIT) THEN ...
Inputs : UNIT = Logical unit number returned by FXBOPEN routine.
Must be a scalar integer.
Opt. Inputs : None.
Outputs : The result of the function is either True (1) or False (0),
depending on whether UNIT points to an open binary table or
not.
Opt. Outputs: None.
Keywords : None.
Calls : FXBFINDLUN
Common : Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions: None.
Side effects: If UNIT is an undefined variable, then False (0) is returned.
If UNIT points to a FITS binary table file that is opened for
write, then False (0) is returned.
Category : Data Handling, I/O, FITS, Generic.
Prev. Hist. : None.
Written : William Thompson, GSFC, 1 July 1993.
Modified : Version 1, William Thompson, GSFC, 1 July 1993.
Version : Version 1, 1 July 1993.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbisopen.pro)
FXBOPEN
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NAME:
FXBOPEN
Purpose :
Open binary table extension in a disk FITS file for reading or updating
Explanation :
Opens a binary table extension in a disk FITS file for reading. The
columns are then read using FXBREAD, and the file is closed when done
with FXBCLOSE.
Use :
FXBOPEN, UNIT, FILENAME, EXTENSION [, HEADER ]
Inputs :
FILENAME = Name of FITS file to be opened. Optional
extension *number* may be specified, in either of
the following formats (using the FTOOLS
convention): FILENAME[EXT] or FILENAME+EXT, where
EXT is 1 or higher. Such an extension
specification takes priority over EXTENSION.
EXTENSION = Either the number of the FITS extension, starting with the
first extension after the primary data unit being one; or a
character string containing the value of EXTNAME to search
for.
Opt. Inputs :
None.
Outputs :
UNIT = Logical unit number of the opened file.
Opt. Outputs:
HEADER = String array containing the FITS binary table extension
header.
Keywords :
NO_TDIM = If set, then any TDIMn keywords found in the header are
ignored.
ACCESS = A scalar string describing access privileges as
one of READ ('R') or UPDATE ('RW').
DEFAULT: 'R'
REOPEN = If set, UNIT must be an already-opened file unit.
FXBOPEN will treat the file as a FITS file.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBOPEN, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
FXBFINDLUN, FXBPARSE, FXHREAD, FXPAR
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The file must be a valid FITS file.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Feb 1992, based on READFITS by J. Woffard and W. Landsman.
W. Thompson, Feb 1992, changed from function to procedure.
W. Thompson, June 1992, fixed up error handling.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 27 May 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 21 June 1994
Extended ERRMSG to call to FXBPARSE
Version 4, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 4, 23 June 1994
Added ACCESS, REOPEN keywords, and FXFILTER package, CM 1999 Feb 03
Added FILENAME[EXT] and FILENAME+EXT extension parsing, CM 1999 Jun 28
Some general tidying, CM 1999 Nov 18
Allow for possible 64bit integer number of bytes W. Landsman Nov 2007
Make Ndata a 64bit integer to deal with larger files, E. Hivon, Mar 2008
(See astrolib/pro/fxbopen.pro)
FXBPARSE
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NAME:
FXBPARSE
Purpose :
Parse the binary table extension header.
Explanation :
Parses the binary table extension header, and store the information
about the format of the binary table in the FXBINTABLE common
block--called from FXBCREATE and FXBOPEN.
Use :
FXBPARSE, ILUN, UNIT, HEADER
Inputs :
ILUN = Index into the arrays in the FXBINTABLE common block.
HEADER = FITS binary table extension header.
Opt. Inputs :
None.
Outputs :
None.
Opt. Outputs:
None.
Keywords :
NO_TDIM = If set, then any TDIMn keywords found in the header are
ignored.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBPARSE, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
FXBFIND, FXBTDIM, FXBTFORM, FXPAR
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
None.
Side effects:
Any TDIMn keywords found for bit arrays (format 'X') are ignored, since
the dimensions would refer to bits, not bytes.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Feb. 1992.
William Thompson, Jan. 1993, modified for renamed FXBTFORM and FXBTDIM.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 June 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 4, Michael Schubnell, University of Michigan, 22 May 1996
Change N_DIMS from short to long integer.
Version 5, W. Landsman, GSFC, 12 Aug 1997
Use double complex datatype, if needed
Version 6, W. Landsman GSFC 30 Aug 1997
Optimized FXPAR; call FXBFIND for speed, CM 1999 Nov 18
Modify DHEAP(ILUN) when opening table now, CM 2000 Feb 22
Default the TZERO/TSCAL tables to double instead of single
precision floating point, CM 2003 Nov 23
Make NAXIS1 and NAXIS2 64-bit integers to deal with large files,
E. Hivon Mar 2008
Remove use of Obsolete !ERR system variable
Version
Version 8 April 2010
(See astrolib/pro/fxbparse.pro)
FXBREAD
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NAME:
FXBREAD
Purpose :
Read a data array from a disk FITS binary table file.
Explanation :
Each call to FXBREAD will read the data from one column and one row
from the FITS data file, which should already have been opened by
FXBOPEN. One needs to call this routine for every column and every row
in the binary table. FXBCLOSE will then close the FITS data file.
Use :
FXBREAD, UNIT, DATA, COL [, ROW ]
Inputs :
UNIT = Logical unit number corresponding to the file containing the
binary table.
COL = Column in the binary table to read data from, either as a
character string containing a column label (TTYPE), or as a
numerical column index starting from column one.
Opt. Inputs :
ROW = Either row number in the binary table to read data from,
starting from row one, or a two element array containing a
range of row numbers to read. If not passed, then the entire
column is read in.
Row must be passed for variable length arrays.
Outputs :
DATA = IDL data array to be read from the file.
Opt. Outputs:
None.
Keywords :
NOSCALE = If set, then the output data will not be scaled using the
optional TSCAL and TZERO keywords in the FITS header.
Default is to scale.
NOIEEE = If set, then the output data is not byte-swapped to
machine order. NOIEEE implies NOSCALE.
Default is to perform the byte-swap.
VIRTUAL = If set, and COL is passed as a name rather than a number,
then if the program can't find a column with that name, it
will then look for a keyword with that name in the header.
Such a keyword would then act as a "virtual column", with the
same value for every row.
DIMENSIONS = Vector array containing the dimensions to be used to read
in the data. Bypasses any dimensioning information stored in
the header. Ignored for bit arrays. If the data type is
double-precision complex, then an extra dimension of 2 is
prepended to the dimensions passed by the user.
NANVALUE= Value signalling data dropout. All points corresponding to
IEEE NaN (not-a-number) are converted to this number.
Ignored unless DATA is of type float, double-precision or
complex.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBREAD, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
FXPAR, WHERE_NEGZERO, WHERENAN
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The binary table file must have been opened with FXBOPEN.
The data must be consistent with the column definition in the binary
table header.
The row number must be consistent with the number of rows stored in the
binary table header.
The number of elements implied by the dimensions keyword must not
exceed the number of elements stored in the file.
Side effects:
If the DIMENSIONS keyword is used, then the number of data points read
in may be less than the number of points stored in the table.
If there are no elements to read in (the number of elements is zero),
then the program sets !ERR to -1, and DATA is unmodified.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Jan 1992.
W. Thompson, Feb 1992, modified to support variable length arrays.
W. Thompson, Jun 1992, modified way that row ranges are read in. No
longer works reiteratively.
W. Thompson, Jun 1992, fixed bug where NANVALUE would be modified by
TSCAL and TZERO keywords.
W. Thompson, Jun 1992, fixed bug when reading character strings.
Treats dimensions better when reading multiple
rows.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 30 June 1993.
Added overwrite keyword to REFORM call to speed up.
Version 3, William Thompson, GSFC, 21 July 1993.
Fixed bug with variable length arrays.
Version 4, William Thompson, GSFC, 29 October 1993.
Added error message for not finding column by name.
Version 5, William Thompson, GSFC, 31 May 1994
Added ERRMSG keyword.
Version 6, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 7, William Thompson, GSFC, 29 December 1994
Fixed bug where single element dimensions were lost.
Version 8, William Thompson, GSFC, 20 March 1995
Fixed bug introduced in version 7.
Version 9, Wayne Landsman, GSFC, 3 July 1996
Fixed bug involving use of virtual keyword.
Version 10, William Thompson, GSFC, 31-Jan-1997
Added call to WHERE_NEGZERO.
Version 11, Wayne Landsman, GSFC, 12 Aug, 1997
Use IDL dcomplex datatype if needed
Version 12, Wayne Landmsan, GSFC, 20 Feb, 1998
Remove call to WHERE_NEGZERO (now part of IEEE_TO_HOST)
Version 13, 18 Nov 1999, CM, Add NOIEEE keyword
Version 14, 21 Aug 2000, William Thompson, GSFC
Catch I/O errors
Version 15, W. Landsman GSFC 10 Dec 2009
Fix Dimension keyword, remove IEEE_TO_HOST
Version :
Version 15, 10 Dec 2009
(See astrolib/pro/fxbread.pro)
FXBREADM
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NAME:
FXBREADM
PURPOSE:
Read multiple columns/rows from a disk FITS binary table file.
EXPLANATION :
A call to FXBREADM will read data from multiple rows and
multiple columns in a single procedure call. Up to forty-nine
columns may be read in a single pass; the number of rows is
limited essentially by available memory. The file should have
already been opened with FXBOPEN. FXBREADM optimizes reading
multiple columns by first reading a large chunk of data from
the FITS file directly, and then slicing the data into columns
within memory. FXBREADM can read variable-length arrays (see
below).
The number of columns is limited to 49 if data are passed by
positional argument. However, this limitation can be overcome
by having FXBREADM return the data in an array of pointers.
The user should set the PASS_METHOD keyword to 'POINTER', and an
array of pointers to the data will be returned in the POINTERS keyword.
The user is responsible for freeing the pointers; however,
FXBREADM will reuse any pointers passed into the procedure, and
hence any pointed-to data will be destroyed.
FXBREADM can also read variable-length columns from FITS
binary tables. Since such data is not of a fixed size, it is
returned as a structure. The structure has the following
elements:
VARICOL: ;; Flag: variable length column (= 1)
N_ELEMENTS: ;; Total number of elements returned
TYPE: ;; IDL data type code (integer)
N_ROWS: ;; Number of rows read from table (integer)
INDICES: ;; Indices of each row's data (integer array)
DATA: ;; Raw data elements (variable type array)
In order to gain access to the Ith row's data, one should
examine DATA(INDICES(I):INDICES(I+1)-1), which is similar in
construct to the REVERSE_INDICES keyword of the HISTOGRAM
function.
CALLING SEQUENCE:
FXBREADM, UNIT, COL, DATA1, [ DATA2, ... DATA48, ROW=, BUFFERSIZE = ]
/NOIEEE, /NOSCALE, /VIRTUAL, NANVALUE=, PASS_METHOD = POINTERS=,
ERRMSG = , WARNMSG = , STATUS = , /DEFAULT_FLOAT]
INPUT PARAMETERS :
UNIT = Logical unit number corresponding to the file containing the
binary table.
COL = An array of columns in the binary table to read data
from, either as character strings containing column
labels (TTYPE), or as numerical column indices
starting from column one.
Outputs :
DATA1, DATA2...DATA48 = A named variable to accept the data values, one
for each column. The columns are stored in order of the
list in COL. If the read operation fails for a
particular column, then the corresponding output Dn
variable is not altered. See the STATUS keyword.
Ignored if PASS_METHOD is 'POINTER'.
OPTIONAL INPUT KEYWORDS:
ROW = Either row number in the binary table to read data from,
starting from row one, or a two element array containing a
range of row numbers to read. If not passed, then the entire
column is read in.
/DEFAULT_FLOAT = If set, then scaling with TSCAL/TZERO is done with
floating point rather than double precision.
/NOIEEE = If set, then then IEEE floating point data will not
be converted to the host floating point format (and
this by definition implies NOSCALE). The user is
responsible for their own floating point conversion.
/NOSCALE = If set, then the output data will not be scaled using the
optional TSCAL and TZERO keywords in the FITS header.
Default is to scale.
VIRTUAL = If set, and COL is passed as a name rather than a number,
then if the program can't find a column with that name, it
will then look for a keyword with that name in the header.
Such a keyword would then act as a "virtual column", with the
same value for every row.
DIMENSIONS = FXBREADM ignores this keyword. It is here for
compatibility only.
NANVALUE= Value signalling data dropout. All points corresponding to
IEEE NaN (not-a-number) are converted to this number.
Ignored unless DATA is of type float, double-precision or
complex.
PASS_METHOD = A scalar string indicating method of passing
data from FXBREADM. Either 'ARGUMENT' (indicating
pass by positional argument), or 'POINTER' (indicating
passing an array of pointers by the POINTERS
keyword).
Default: 'ARGUMENT'
POINTERS = If PASS_METHOD is 'POINTER' then an array of IDL
pointers is returned in this keyword, one for each
requested column. Any pointers passed into FXBREADM will
have their pointed-to data destroyed. Ultimately the
user is responsible for deallocating pointers.
BUFFERSIZE = Raw data are transferred from the file in chunks
to conserve memory. This is the size in bytes of
each chunk. If a value of zero is given, then all
of the data are transferred in one pass. Default is
32768 (32 kB).
OPTIONAL OUTPUT KEYWORDS:
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBREAD, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
WARNMSG = Messages which are considered to be non-fatal
"warnings" are returned in this output string.
Note that if some but not all columns are
unreadable, this is considered to be non-fatal.
STATUS = An output array containing the status for each
column read, 1 meaning success and 0 meaning failure.
Calls :
IEEE_TO_HOST, FXPAR(), WHERENAN()
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The binary table file must have been opened with FXBOPEN.
The data must be consistent with the column definition in the binary
table header.
The row number must be consistent with the number of rows stored in the
binary table header.
Generaly speaking, FXBREADM will be faster than iterative
calls to FXBREAD when (a) a large number of columns is to be
read or (b) the size in bytes of each cell is small, so that
the overhead of the FOR loop in FXBREAD becomes significant.
SIDE EFFECTS:
If there are no elements to read in (the number of elements is zero),
then the program sets !ERR to -1, and DATA is unmodified.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
C. Markwardt, based in concept on FXBREAD version 12 from
IDLASTRO, but with significant and
major changes to accomodate the
multiple row/column technique. Mostly
the parameter checking and general data
flow remain.
C. Markwardt, updated to read variable length arrays, and to
pass columns by handle or pointer.
20 Jun 2001
C. Markwardt, try to conserve memory when creating the arrays
13 Oct 2001
Handle case of GE 50 columns, C. Markwardt, 18 Apr 2002
Handle case where TSCAL/TZERO changes type of column,
C. Markwardt, 23 Feb 2003
Fix bug in handling of FOUND and numeric columns,
C. Markwardt 12 May 2003
Removed pre-V5.0 HANDLE options W. Landsman July 2004
Fix bug when HANDLE options were removed, July 2004
Handle special cases of TSCAL/TZERO which emulate unsigned
integers, Oct 2003
Add DEFAULT_FLOAT keyword to select float values instead of double
for TSCAL'ed, June 2004
Read 64bit integer columns, E. Hivon, Mar 2008
Add support for columns with TNULLn keywords, C. Markwardt, Apr 2010
Add support for files larger than 2 GB, C. Markwardt, 2012-04-17
(See astrolib/pro/fxbreadm.pro)
FXBSTATE()
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NAME:
FXBSTATE()
PURPOSE:
Returns the state of a FITS binary table.
Explanation : This procedure returns the state of a FITS binary table that
was either opened for read with the command FXBOPEN, or for
write with the command FXBCREATE.
Use : Result = FXBSTATE(UNIT)
Inputs : UNIT = Logical unit number returned by FXBOPEN routine.
Must be a scalar integer.
Opt. Inputs : None.
Outputs : The result of the function is the state of the FITS binary
table that UNIT points to. This can be one of three values:
0 = Closed
1 = Open for read
2 = Open for write
Opt. Outputs: None.
Keywords : None.
Calls : FXBFINDLUN
Common : Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions: None.
Side effects: If UNIT is an undefined variable, then 0 (closed) is returned.
Category : Data Handling, I/O, FITS, Generic.
Prev. Hist. : None.
Written : William Thompson, GSFC, 1 July 1993.
Modified : Version 1, William Thompson, GSFC, 1 July 1993.
Version : Version 1, 1 July 1993.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbstate.pro)
FXBTDIM()
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NAME:
FXBTDIM()
Purpose :
Parse TDIM-like kwywords.
Explanation :
Parses the value of a TDIM-like keyword (e.g. TDIMnnn, TDESC, etc.) to
return the separate elements contained within.
Use :
Result = FXBTDIM( TDIM_KEYWORD )
Inputs :
TDIM_KEYWORD = The value of a TDIM-like keyword. Must be a
character string of the form "(value1,value2,...)".
If the parentheses characters are missing, then the
string is simply returned as is, without any further
processing.
Opt. Inputs :
None.
Outputs :
The result of the function is a character string array containing the
values contained within the keyword parameter. If a numerical result
is desired, then simply call, e.g.
Result = FIX( FXBTDIM( TDIM_KEYWORD ))
Opt. Outputs:
None.
Keywords :
None.
Calls :
GETTOK
Common :
None.
Restrictions:
The input parameter must have the proper format. The separate values
must not contain the comma character. TDIM_KEYWORD must not be an
array.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Jan. 1992.
William Thompson, Jan. 1993, renamed to be compatible with DOS
limitations.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version :
Version 1, 12 April 1993.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbtdim.pro)
FXBTFORM
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NAME:
FXBTFORM
PURPOSE :
Returns information about FITS binary table columns.
EXPLANATION :
Procedure to return information about the format of the various columns
in a FITS binary table.
Use :
FXBTFORM,HEADER,TBCOL,IDLTYPE,FORMAT,NUMVAL,MAXVAL
Inputs :
HEADER = Fits binary table header.
Opt. Inputs :
None.
Outputs :
TBCOL = Array of starting column positions in bytes.
IDLTYPE = IDL data types of columns.
FORMAT = Character code defining the data types of the columns.
NUMVAL = Number of elements of the data arrays in the columns.
MAXVAL = Maximum number of elements for columns containing variable
length arrays, or zero otherwise.
Opt. Outputs:
None.
Keywords :
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBTFORM, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
FXPAR
Common :
None.
Restrictions:
None.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Feb. 1992, from TBINFO by D. Lindler.
W. Thompson, Jan. 1993, renamed to be compatible with DOS limitations.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 June 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 4, William Thompson, GSFC, 9 April 1997
Modified so that variable length arrays can be read, even if
the maximum array size is not in the header.
Version 5 Wayne Landsman, GSFC, August 1997
Recognize double complex array type if since IDL version 4.0
Version 6 Optimized FXPAR call, CM 1999 Nov 18
Version 7: Wayne Landsman, GSFC Feb 2006
Added support for 64bit integer K format
Version:
Version 8: Wayne Landsman GSFC Apr 2010
Remove use of obsolete !ERR variable
(See astrolib/pro/fxbtform.pro)
FXBWRITE
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NAME:
FXBWRITE
Purpose :
Write a binary data array to a disk FITS binary table file.
Explanation :
Each call to FXBWRITE will write to the data file, which should already
have been created and opened by FXBCREATE. One needs to call this
routine for every column and every row in the binary table. FXBFINISH
will then close the file.
Use :
FXBWRITE, UNIT, DATA, COL, ROW
Inputs :
UNIT = Logical unit number corresponding to the file containing the
binary table.
DATA = IDL data array to be written to the file.
COL = Column in the binary table to place data in, starting from
column one.
ROW = Row in the binary table to place data in, starting from row
one.
Opt. Inputs :
None.
Outputs :
None.
Opt. Outputs:
None.
Keywords :
BIT = Number of bits in bit mask arrays (type "X"). Only used if
the column is of variable size.
NANVALUE= Value signalling data dropout. All points corresponding to
this value are set to be IEEE NaN (not-a-number). Ignored
unless DATA is of type float, double-precision or complex.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBWRITE, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
HOST_TO_IEEE
Common :
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
Restrictions:
The binary table file must have been opened with FXBCREATE.
The data must be consistent with the column definition in the binary
table header.
The row number must be consistent with the number of rows stored in the
binary table header.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Jan 1992, based on WRITEFITS by J. Woffard and W. Landsman.
W. Thompson, Feb 1992, modified to support variable length arrays.
W. Thompson, Feb 1992, removed all references to temporary files.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 July 1993.
Fixed bug with variable length arrays.
Version 3, William Thompson, GSFC, 31 May 1994
Added ERRMSG keyword.
Version 4, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 5, Wayne Landsman, GSFC, 12 Aug 1997
Recognize IDL double complex data type
Version :
Version 5, 12 August 1997
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxbwrite.pro)
FXBWRITM
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NAME:
FXBWRITM
PURPOSE:
Write multiple columns/rows to a disk FITS binary table file.
EXPLANATION :
A call to FXBWRITM will write multiple rows and multiple
columns to a binary table in a single procedure call. Up to
fifty columns may be read in a single pass. The file should
have already been opened with FXBOPEN (with write access) or
FXBCREATE. FXBWRITM optimizes writing multiple columns by
first writing a large chunk of data to the FITS file all at
once. FXBWRITM cannot write variable-length arrays; use
FXBWRITE instead.
The number of columns is limited to 50 if data are passed by
positional argument. However, this limitation can be overcome
by passing pointers to FXBWRITM. The user should set the PASS_METHOD
keyword to 'POINTER' as appropriate, and an array of pointers to
the data in the POINTERS keyword. The user is responsible for freeing
the pointers.
CALLING SEQUENCE:
FXBWRITM, UNIT, COL, D0, D1, D2, ..., [ ROW= , PASS_METHOD, NANVALUE=
POINTERS=, BUFFERSIZE= ]
INPUT PARAMETERS:
UNIT = Logical unit number corresponding to the file containing the
binary table.
D0,..D49= An IDL data array to be written to the file, one for
each column. These parameters will be igonred if data
is passed through the POINTERS keyword.
COL = Column in the binary table to place data in. May be either
a list of column numbers where the first column is one, or
a string list of column names.
OPTIONAL INPUT KEYWORDS:
ROW = Either row number in the binary table to write data to,
starting from row one, or a two element array containing a
range of row numbers to write. If not passed, then
the entire column is written.
NANVALUE= Value signalling data dropout. All points corresponding to
this value are set to be IEEE NaN (not-a-number). Ignored
unless DATA is of type float, double-precision or complex.
NOSCALE = If set, then TSCAL/TZERO values are ignored, and data is
written exactly as supplied.
PASS_METHOD = A scalar string indicating method of passing
data to FXBWRITM. One of 'ARGUMENT' (indicating
pass by positional argument), or'POINTER' (indicating
passing an array of pointers by the POINTERS
keyword).
Default: 'ARGUMENT'
POINTERS = If PASS_METHOD is 'POINTER' then the user must pass
an array of IDL pointers to this keyword, one for
each column. Ultimately the user is responsible for
deallocating pointers.
BUFFERSIZE = Data are transferred in chunks to conserve
memory. This is the size in bytes of each chunk.
If a value of zero is given, then all of the data
are transferred in one pass. Default is 32768 (32
kB).
OPTIONAL OUTPUT KEYWORDS:
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXBWRITE, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
WARNMSG = Messages which are considered to be non-fatal
"warnings" are returned in this output string.
STATUS = An output array containing the status for each
read, 1 meaning success and 0 meaning failure.
PROCEDURE CALLS:
None.
EXAMPLE:
Write a binary table 'sample.fits' giving 43 X,Y positions and a
21 x 21 PSF at each position:
(1) First, create sample values
x = findgen(43) & y = findgen(43)+1 & psf = randomn(seed,21,21,43)
(2) Create primary header, write it to disk, and make extension header
fxhmake,header,/initialize,/extend,/date
fxwrite,'sample.fits',header
fxbhmake,header,43,'TESTEXT','Test binary table extension'
(3) Fill extension header with desired column names
fxbaddcol,1,header,x[0],'X' ;Use first element in each array
fxbaddcol,2,header,y[0],'Y' ;to determine column properties
fxbaddcol,3,header,psf[*,*,0],'PSF'
(4) Write extension header to FITS file
fxbcreate,unit,'sample.fits',header
(5) Use FXBWRITM to write all data to the extension in a single call
fxbwritm,unit,['X','Y','PSF'], x, y, psf
fxbfinish,unit ;Close the file
COMMON BLOCKS:
Uses common block FXBINTABLE--see "fxbintable.pro" for more
information.
RESTRICTIONS:
The binary table file must have been opened with FXBCREATE or
FXBOPEN (with write access).
The data must be consistent with the column definition in the binary
table header.
The row number must be consistent with the number of rows stored in the
binary table header.
A PASS_METHOD of POINTER does not use the EXECUTE() statement and can be
used with the IDL Virtual Machine. However, the EXECUTE() statement is
used when the PASS_METHOD is by arguments.
CATEGORY:
Data Handling, I/O, FITS, Generic.
PREVIOUS HISTORY:
C. Markwardt, based on FXBWRITE and FXBREADM (ver 1), Jan 1999
WRITTEN:
Craig Markwardt, GSFC, January 1999.
MODIFIED:
Version 1, Craig Markwardt, GSFC 18 January 1999.
Documented this routine, 18 January 1999.
C. Markwardt, added ability to pass by handle or pointer.
Some bug fixes, 20 July 2001
W. Landsman/B.Schulz Allow more than 50 arguments when using pointers
W. Landsman Remove pre-V5.0 HANDLE options July 2004
W. Landsman Remove EXECUTE() call with POINTERS May 2005
C. Markwardt Allow the output table to have TSCAL/TZERO
keyword values; if that is the case, then the passed values
will be quantized to match those scale factors before being
written. Sep 2007
E. Hivon: write 64bit integer and double precison columns, Mar 2008
C. Markwardt Allow unsigned integers, which have special
TSCAL/TZERO values. Feb 2009
C. Markwardt Add support for files larger than 2 GB, 2012-04-17
(See astrolib/pro/fxbwritm.pro)
FXFINDEND
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NAME:
FXFINDEND
Purpose :
Find the end of a FITS file.
Explanation :
This routine finds the end of the last logical record in a FITS file,
which may be different from that of the physical end of the file. Each
FITS header is read in and parsed, and the file pointer is moved to
where the next FITS extension header would be if there is one, or to
the end of the file if not.
Use :
FXFINDEND, UNIT [, EXTENSION]
Inputs :
UNIT = Logical unit number for the opened file.
Opt. Inputs :
None.
Outputs :
None.
Opt. Outputs:
EXTENSION = The extension number that a new extension would
have if placed at the end of the file.
Keywords :
None.
Calls :
FXHREAD, FXPAR
Common :
None.
Restrictions:
The file must have been opened for block I/O. There must not be any
FITS "special records" at the end of the file.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Feb. 1992.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version :
Version 1, 12 April 1993.
Converted to IDL V5.0 W. Landsman September 1997
Added EXTENSION parameter, CM 1999 Nov 18
Allow for possible 64bit integer number of bytes W. Landsman Nov 2007
make Ndata a long64 to deal with large files. E. Hivon Mar 2008
(See astrolib/pro/fxfindend.pro)
FXHCLEAN
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NAME:
FXHCLEAN
Purpose :
Removes required keywords from FITS header.
Explanation :
Removes any keywords relevant to array structure from a FITS header,
preparatory to recreating it with the proper values.
Use :
FXHCLEAN, HEADER
Inputs :
HEADER = FITS header to be cleaned.
Opt. Inputs :
None.
Outputs :
HEADER = The cleaned FITS header is returned in place of the input
array.
Opt. Outputs:
None.
Keywords :
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXHCLEAN, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
SXDELPAR, FXPAR
Common :
None.
Restrictions:
HEADER must be a string array containing a properly formatted FITS
header.
Side effects:
Warning: when cleaning a binary table extension header, not all of the
keywords pertaining to columns in the table may be removed.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Jan 1992.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 31 May 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 4, William Thompson, GSFC, 30 December 1994
Added TCUNIn to list of column keywords to be removed.
Version :
Version 4, 30 December 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxhclean.pro)
FXHMAKE
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NAME:
FXHMAKE
Purpose :
Create a basic FITS header array.
Explanation :
Creates a basic header array with all the required keywords. This
defines a basic structure which can then be added to or modified by
other routines.
Use :
FXHMAKE, HEADER [, DATA ]
Inputs :
None required.
Opt. Inputs :
DATA = IDL data array to be written to file. It must be in the
primary data unit unless the XTENSION keyword is supplied.
This array is used to determine the values of the BITPIX and
NAXIS, etc. keywords.
If not passed, then BITPIX is set to eight, NAXIS is set to
zero, and no NAXISnnn keywords are included in this
preliminary header.
Outputs :
HEADER = String array containing FITS header.
Opt. Outputs:
None.
Keywords :
INITIALIZE = If set, then the header is completely initialized, and any
previous entries are lost.
EXTEND = If set, then the keyword EXTEND is inserted into the file,
with the value of "T" (true).
DATE = If set, then the DATE keyword is added to the header.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXHMAKE, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
XTENSION - If set, then the header is appropriate for an image
extension, rather than the primary data unit.
Calls :
GET_DATE, FXADDPAR, FXHCLEAN
Common :
None.
Restrictions:
Groups are not currently supported.
Side effects:
BITPIX, NAXIS, etc. are defined such that complex arrays are stored as
floating point, with an extra first dimension of two elements (real and
imaginary parts).
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Jan 1992, from SXHMAKE by D. Lindler and M. Greason.
Differences include:
* Use of FITS standard (negative BITPIX) to signal floating
point numbers instead of (SDAS/Geis) DATATYPE keyword.
* Storage of complex numbers as pairs of real numbers.
* Support for EXTEND keyword, and for cases where there is no
primary data array.
* Insertion of DATE record made optional. Only required FITS
keywords are inserted automatically.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 21 June 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 4, Wayne Landsman, GSFC, 12 August 1997
Recognize double complex data type
Converted to IDL V5.0 W. Landsman September 1997
Version 6, William Thompson, GSFC, 22 September 2004
Recognize unsigned integer types.
Version 6.1, C. Markwardt, GSFC, 19 Jun 2005
Add the XTENSION keyword, which writes an XTENSION
keyword instead of SIMPLE.
Version :
Version 6.1, 19 June 2005
(See astrolib/pro/fxhmake.pro)
FXHMODIFY
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NAME:
FXHMODIFY
PURPOSE :
Modify a FITS header in a file on disk.
Explanation :
Opens a FITS file, and adds or modifies a parameter in the FITS header.
Can be used for either the main header, or for an extension header.
The modification is performed directly on the disk file.
Use :
FXHMODIFY, FILENAME, NAME, VALUE, COMMENT
Inputs :
FILENAME = String containing the name of the file to be read.
NAME = Name of parameter, scalar string If NAME is already in the
header the value and possibly comment fields are modified.
Otherwise a new record is added to the header. If NAME is
equal to either "COMMENT" or "HISTORY" then the value will be
added to the record without replacement. In this case the
comment parameter is ignored.
VALUE = Value for parameter. The value expression must be of the
correct type, e.g. integer, floating or string. String
values of 'T' or 'F' are considered logical values.
Opt. Inputs :
COMMENT = String field. The '/' is added by this routine. Added
starting in position 31. If not supplied, or set equal to ''
(the null string), then any previous comment field in the
header for that keyword is retained (when found).
Outputs :
None.
Opt. Outputs:
None.
Keywords :
EXTENSION = Either the number of the FITS extension, starting with the
first extension after the primary data unit being one; or a
character string containing the value of EXTNAME to search
for. If not passed, then the primary FITS header is
modified.
BEFORE = Keyword string name. The parameter will be placed before the
location of this keyword. For example, if BEFORE='HISTORY'
then the parameter will be placed before the first history
location. This applies only when adding a new keyword;
keywords already in the header are kept in the same position.
AFTER = Same as BEFORE, but the parameter will be placed after the
location of this keyword. This keyword takes precedence over
BEFORE.
FORMAT = Specifies FORTRAN-like format for parameter, e.g. "F7.3". A
scalar string should be used. For complex numbers the format
should be defined so that it can be applied separately to the
real and imaginary parts.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXHMODIFY, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
FXHREAD, FXPAR, FXADDPAR, BLKSHIFT
Restrictions:
This routine can not be used to modify any of the keywords that control
the structure of the FITS file, e.g. BITPIX, NAXIS, PCOUNT, etc. Doing
so could corrupt the readability of the FITS file.
Example:
Modify the name 'OBJECT' keyword in the primary FITS header of a FITS
file 'spec98.ccd' to contain the value 'test domeflat'
IDL> fxhmodify, 'spec98.ccd', 'OBJECT', 'test domeflat'
Side effects:
If adding a record to the FITS header would increase the
number of 2880 byte records stored on disk, then the file is
enlarged before modification, unless the NOGROW keyword is passed.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
None.
Written :
William Thompson, GSFC, 3 March 1994.
Modified :
Version 1, William Thompson, GSFC, 3 March 1994.
Version 2, William Thompson, GSFC, 31 May 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 3.1 Wayne Landsman GSFC 17 March 2006
Fix problem in BLKSHIFT call if primary header extended
Version 3.2 W. Landsman 14 November 204
Allow for need for 64bit number of bytes
; Version :
Version 3.2, 14 Nov 2007
(See astrolib/pro/fxhmodify.pro)
FXHREAD
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NAME:
FXHREAD
Purpose :
Reads a FITS header from an opened disk file.
Explanation :
Reads a FITS header from an opened disk file.
Use :
FXHREAD, UNIT, HEADER [, STATUS ]
Inputs :
UNIT = Logical unit number.
Opt. Inputs :
Outputs :
HEADER = String array containing the FITS header.
Opt. Outputs:
STATUS = Condition code giving the status of the read. Normally, this
is zero, but is set to !ERR if an error occurs, or if the
first byte of the header is zero (ASCII null).
Keywords :
None.
Calls :
None.
Common :
None.
Restrictions:
The file must already be positioned at the start of the header. It
must be a proper FITS file.
Side effects:
The file ends by being positioned at the end of the FITS header, unless
an error occurs.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Feb 1992, from READFITS by J. Woffard and W. Landsman.
W. Thompson, Aug 1992, added test for SIMPLE keyword.
Written :
William Thompson, GSFC, February 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version :
Version 1, 12 April 1993.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxhread.pro)
FXMOVE
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NAME:
FXMOVE
PURPOSE:
Skip to a specified extension number or name in a FITS file
CALLING SEQUENCE:
STATUS=FXMOVE(UNIT, EXT, /Silent)
STATUS=FXMOVE(UNIT, EXTNAME, /Silent, EXT_NO=, ERRMSG= )
INPUT PARAMETERS:
UNIT = An open unit descriptor for a FITS data stream.
EXTEN = Number of extensions to skip.
or
Scalar string giving extension name (in the EXTNAME keyword)
OPTIONAL INPUT PARAMETER:
/SILENT - If set, then any messages about invalid characters in the
FITS file are suppressed.
OPTIONAL OUTPUT PARAMETER:
ERRMSG = If this keyword is present, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned.
EXT_NO - Extension number, scalar integer, useful if the user supplied
an extension name in the EXTEN parameter
RETURNS:
0 if successful.
-1 if an error is encountered.
COMMON BLOCKS:
None.
SIDE EFFECTS:
Repositions the file pointer.
PROCEDURE:
Each FITS header is read in and parsed, and the file pointer is moved
to where the next FITS extension header until the desired
extension is reached.
PROCEDURE CALLS:
FXPAR(), MRD_HREAD, MRD_SKIP
MODIFICATION HISTORY:
Extracted from FXPOSIT 8-March-2000 by T. McGlynn
Added /SILENT keyword 14-Dec-2000 by W. Landsman
Save time by not reading the full header W. Landsman Feb. 2003
Allow extension name to be specified, added EXT_NO, ERRMSG keywords
W. Landsman December 2006
Make search for EXTNAME case-independent W.Landsman March 2007
Avoid round-off error for very large extensions N. Piskunov Dec 2007
Assume since V6.1 (/INTEGER keyword available to PRODUCT() ) Dec 2007
Capture error message from MRD_HREAD (must be used with post-June 2009
version of MRD-HREAD) W. Landsman July 2009
(See astrolib/pro/fxmove.pro)
FXPAR()
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NAME:
FXPAR()
PURPOSE:
Obtain the value of a parameter in a FITS header.
EXPLANATION:
The first 8 chacters of each element of HDR are searched for a match to
NAME. If the keyword is one of those allowed to take multiple values
("HISTORY", "COMMENT", or " " (blank)), then the value is taken
as the next 72 characters. Otherwise, it is assumed that the next
character is "=", and the value (and optional comment) is then parsed
from the last 71 characters. An error occurs if there is no parameter
with the given name.
If the value is too long for one line, it may be continued on to the
the next input card, using the CONTINUE Long String Keyword convention.
For more info, http://fits.gsfc.nasa.gov/registry/continue_keyword.html
Complex numbers are recognized as two numbers separated by one or more
space characters.
If a numeric value has no decimal point (or E or D) it is returned as
type LONG. If it contains more than 8 numerals, or contains the
character 'D', then it is returned as type DOUBLE. Otherwise it is
returned as type FLOAT. If an integer is too large to be stored as
type LONG, then it is returned as DOUBLE.
CALLING SEQUENCE:
Result = FXPAR( HDR, NAME [, ABORT, COUNT=, COMMENT=, /NOCONTINUE ] )
Result = FXPAR(HEADER,'DATE') ;Finds the value of DATE
Result = FXPAR(HEADER,'NAXIS*') ;Returns array dimensions as
;vector
REQUIRED INPUTS:
HDR = FITS header string array (e.g. as returned by FXREAD). Each
element should have a length of 80 characters
NAME = String name of the parameter to return. If NAME is of the
form 'keyword*' then an array is returned containing values
of keywordN where N is an integer. The value of keywordN
will be placed in RESULT(N-1). The data type of RESULT will
be the type of the first valid match of keywordN
found, unless DATATYPE is given.
OPTIONAL INPUT:
ABORT = String specifying that FXPAR should do a RETALL if a
parameter is not found. ABORT should contain a string to be
printed if the keyword parameter is not found. If not
supplied, FXPAR will return with a negative !err if a keyword
is not found.
DATATYPE = A scalar value, indicating the type of vector
data. All keywords will be cast to this type.
Default: based on first keyword.
Example: DATATYPE=0.0D (cast data to double precision)
START = A best-guess starting position of the sought-after
keyword in the header. If specified, then FXPAR
first searches for scalar keywords in the header in
the index range bounded by START-PRECHECK and
START+POSTCHECK. This can speed up keyword searches
in large headers. If the keyword is not found, then
FXPAR searches the entire header.
If not specified then the entire header is searched.
Searches of the form 'keyword*' also search the
entire header and ignore START.
Upon return START is changed to be the position of
the newly found keyword. Thus the best way to
search for a series of keywords is to search for
them in the order they appear in the header like
this:
START = 0L
P1 = FXPAR('P1', START=START)
P2 = FXPAR('P2', START=START)
PRECHECK = If START is specified, then PRECHECK is the number
of keywords preceding START to be searched.
Default: 5
POSTCHECK = If START is specified, then POSTCHECK is the number
of keywords after START to be searched.
Default: 20
OUTPUT:
The returned value of the function is the value(s) associated with the
requested keyword in the header array.
If the parameter is complex, double precision, floating point, long or
string, then the result is of that type. Apostrophes are stripped from
strings. If the parameter is logical, 1 is returned for T, and 0 is
returned for F.
If NAME was of form 'keyword*' then a vector of values are returned.
OPTIONAL INPUT KEYWORDS:
/NOCONTINUE = If set, then continuation lines will not be read, even
if present in the header
OPTIONAL OUTPUT KEYWORD:
COUNT = Optional keyword to return a value equal to the number of
parameters found by FXPAR.
COMMENTS= Array of comments associated with the returned values.
PROCEDURE CALLS:
GETTOK(), VALID_NUM
SIDE EFFECTS:
The system variable !err is set to -1 if parameter not found, 0 for a
scalar value returned. If a vector is returned it is set to the number
of keyword matches found.
If a keyword occurs more than once in a header, a warning is given,
and the first occurence is used. However, if the keyword is "HISTORY",
"COMMENT", or " " (blank), then multiple values are returned.
NOTES:
The functions SXPAR() and FXPAR() are nearly identical, although
FXPAR() has slightly more sophisticated parsing. There is no
particular reason for having two nearly identical procedures, but
both are too widely used to drop either one.
REVISION HISTORY:
Version 1, William Thompson, GSFC, 12 April 1993.
Adapted from SXPAR
Version 2, William Thompson, GSFC, 14 October 1994
Modified to use VALID_NUM instead of STRNUMBER. Inserted
additional call to VALID_NUM to trap cases where character
strings did not contain quotation marks.
Version 3, William Thompson, GSFC, 22 December 1994
Fixed bug with blank keywords, following suggestion by Wayne
Landsman.
Version 4, Mons Morrison, LMSAL, 9-Jan-98
Made non-trailing ' for string tag just be a warning (not
a fatal error). It was needed because "sxaddpar" had an
error which did not write tags properly for long strings
(over 68 characters)
Version 5, Wayne Landsman GSFC, 29 May 1998
Fixed potential problem with overflow of LONG values
Version 6, Craig Markwardt, GSFC, 28 Jan 1998,
Added CONTINUE parsing
Version 7, Craig Markwardt, GSFC, 18 Nov 1999,
Added START, PRE/POSTCHECK keywords for better
performance
Version 8, Craig Markwardt, GSFC, 08 Oct 2003,
Added DATATYPE keyword to cast vector keywords type
Version 9, Paul Hick, 22 Oct 2003, Corrected bug (NHEADER-1)
Version 10, W. Landsman, GSFC 2 May 2012
Keywords of form "name_0" could confuse vector extractions
(See astrolib/pro/fxpar.pro)
FXPARPOS()
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NAME:
FXPARPOS()
Purpose :
Finds position to insert record into FITS header.
Explanation :
Finds the position to insert a record into a FITS header. Called from
FXADDPAR.
Use :
Result = FXPARPOS(KEYWRD, IEND [, BEFORE=BEFORE ] [, AFTER=AFTER ])
Inputs :
KEYWRD = Array of eight-character keywords in header.
IEND = Position of END keyword.
Opt. Inputs :
None.
Outputs :
Result of function is position to insert record.
Opt. Outputs:
None.
Keywords :
BEFORE = Keyword string name. The parameter will be placed before the
location of this keyword. For example, if BEFORE='HISTORY'
then the parameter will be placed before the first history
location. This applies only when adding a new keyword;
keywords already in the header are kept in the same position.
AFTER = Same as BEFORE, but the parameter will be placed after the
location of this keyword. This keyword takes precedence over
BEFORE.
If neither BEFORE or AFTER keywords are passed, then IEND is returned.
Calls :
None.
Common :
None.
Restrictions:
KEYWRD and IEND must be consistent with the relevant FITS header.
Side effects:
None.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
William Thompson, Jan 1992.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version :
Version 1, 12 April 1993.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/fxparpos.pro)
FXPOSIT
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NAME:
FXPOSIT
PURPOSE:
Return the unit number of a FITS file positioned at specified extension
EXPLANATION:
The FITS file will be ready to be read at the beginning of the
specified extension. Either an extension number or extension name
can be specified. Called by headfits.pro, mrdfits.pro
Modified in March 2009 to set the /SWAP_IF_LITTLE_ENDIAN keyword
when opening a file, and **may not be compatible with earlier versions**
CALLING SEQUENCE:
unit=FXPOSIT(FILE, EXT_NO_OR_NAME, /READONLY, COMPRESS=program,
UNIXPIPE=, ERRMSG= , EXTNUM= , UNIT=, /SILENT
/FPACK, /NO_FPACK
INPUT PARAMETERS:
FILE = FITS file name, scalar string. If an empty string is supplied
then the user will be prompted for the file name. The user
will also be prompted if a wild card is supplied, and more than
one file matches the wildcard.
EXT_NO_OR_NAME = Either the extension to be moved to (scalar
nonnegative integer) or the name of the extension to read
(scalar string)
RETURNS:
Unit number of file or -1 if an error is detected.
OPTIONAL INPUT KEYWORD PARAMETER:
COMPRESS - If this keyword is set and non-zero, then then treat
the file as compressed. If 1 assume a gzipped file.
and use IDLs internal decompression facility. For Unix
compressed or bzip2 compressed files spawn off a process to
decompress and use its output as the FITS stream. If the
keyword is not 1, then use its value as a string giving the
command needed for decompression.
/FPACK - Signal that the file is compressed with the FPACK software.
http://heasarc.gsfc.nasa.gov/fitsio/fpack/ ) By default,
(FXPOSIT will assume that if the file name extension ends in
.fz that it is fpack compressed.) The FPACK software must
be installed on the system
/NO_FPACK - The unit will only be used to read the FITS header. In
that case FPACK compressed files need not be uncompressed.
LUNIT - Integer giving the file unit number. Use this keyword if
you want to override the default use of GET_LUN to obtain
a unit number.
/READONLY - If this keyword is set and non-zero, then OPENR rather
than OPENU will be used to open the FITS file. Note that
compressed files are always set to /READONLY
/SILENT If set, then suppress any messages about invalid characters
in the FITS file.
OPTIONAL OUTPUT KEYWORDS:
EXTNUM - Nonnegative integer give the extension number actually read
Useful only if the extension was specified by name.
ERRMSG = If this keyword is present, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned.
UNIXPIPE - If set to 1, then the FITS file was opened with a UNIX pipe
rather than with the OPENR command. This is only required
when reading a FPACK, bzip or Unix compressed file. Note
that automatic byteswapping cannnot be set for a Unix pipe,
since the SWAP_IF_LITTLE_ENDIAN keyword is only available for the
OPEN command, and it is the responsibilty of the calling
routine to perform the byteswapping.
SIDE EFFECTS:
Opens and returns a file unit.
PROCEDURE:
Open the appropriate file, or spawn a command and intercept
the output.
Call FXMOVE to get to the appropriate extension.
PROCEDURE CALLS:
FXMOVE()
MODIFICATION HISTORY:
Derived from William Thompson's FXFINDEND routine.
Modified by T.McGlynn, 5-October-1994.
Modified by T.McGlynn, 25-Feb-1995 to handle compressed
files. Pipes cannot be accessed using FXHREAD so
MRD_HREAD was written.
W. Landsman 23-Apr-1997 Force the /bin/sh shell when uncompressing
T. McGlynn 03-June-1999 Use /noshell option to get rid of processes left by spawn.
Use findfile to retain ability to use wildcards
W. Landsman 03-Aug-1999 Use EXPAND_TILDE under Unix to find file
T. McGlynn 04-Apr-2000 Put reading code into FXMOVE,
additional support for compression from D.Palmer.
W. Landsman/D.Zarro 04-Jul-2000 Added test for !VERSION.OS EQ 'Win32' (WinNT)
W. Landsman 12-Dec-2000 Added /SILENT keyword
W. Landsman April 2002 Use FILE_SEARCH for V5.5 or later
W. Landsman Feb 2004 Assume since V5.3 (OPENR,/COMPRESS available)
W. Landsman,W. Thompson, 2-Mar-2004, Add support for BZIP2
W. Landsman Don't leave open file if an error occurs
W. Landsman Sep 2004 Treat FTZ extension as gzip compressed
W. Landsman Feb 2006 Removed leading spaces (prior to V5.5)
W. Landsman Nov 2006 Allow specification of extension name
Added EXTNUM, ERRMSG keywords
W. Landsman/N.Piskunov Dec 2007 Added LUNIT keyword
W. Landsman Mar 2009 OPEN with /SWAP_IF_LITTLE_ENDIAN
Added UNIXPIPE output keyword
N. Rich May 2009 Check if filename is an empty string
W. Landsman May 2009 Support FPACK compressed files
Added /FPACK, /HEADERONLY keywords
W.Landsman July 2009 Deprecated /HEADERONLY add /NO_FPACK
W.Landsman July 2011 Check for SIMPLE in first 8 chars
Use gunzip to decompress Unix. Z file since compress utility
often not installed anymore)
W. Landsman October 2012 Add .fz extension if /FPACK set
(See astrolib/pro/fxposit.pro)
FXREAD
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NAME:
FXREAD
Purpose :
Read basic FITS files.
Explanation :
Read an image array from a disk FITS file. Optionally allows the
user to read in only a subarray and/or every Nth pixel.
Use :
FXREAD, FILENAME, DATA [, HEADER [, I1, I2 [, J1, J2 ]] [, STEP]]
Inputs :
FILENAME = String containing the name of the file to be read.
Opt. Inputs :
I1,I2 = Data range to read in the first dimension. If passed, then
HEADER must also be passed. If not passed, or set to -1,-1,
then the entire range is read.
J1,J2 = Data range to read in the second dimension. If passed, then
HEADER and I1,J2 must also be passed. If not passed, or set
to -1,-1, then the entire range is read.
STEP = Step size to use in reading the data. If passed, then
HEADER must also be passed. Default value is 1. Ignored if
less than 1.
Outputs :
DATA = Data array to be read from the file.
Opt. Outputs:
HEADER = String array containing the header for the FITS file.
Keywords :
/COMPRESS - If this keyword is set and non-zero, then then treat
the file as gzip compressed. By default FXREAD assumes
the file is gzip compressed if it ends in ".gz"
NANVALUE = Value signalling data dropout. All points corresponding to
IEEE NaN (not-a-number) are set to this value. Ignored
unless DATA is of type float or double-precision.
EXTENSION = FITS extension. It can be a scalar integer,
indicating the extension number (extension number 0
is the primary HDU). It can also be a scalar string,
indicating the extension name (EXTNAME keyword).
Default: 0 (primary HDU)
PROMPT = If set, then the optional parameters are prompted for at the
keyboard.
AVERAGE = If set, then the array size is reduced by averaging pixels
together rather than by subselecting pixels. Ignored unless
STEP is nontrivial. Note: this is much slower.
YSTEP = If passed, then STEP is the step size in the 1st dimension,
and YSTEP is the step size in the 2nd dimension. Otherwise,
STEP applies to both directions.
NOSCALE = If set, then the output data will not be scaled using the
optional BSCALE and BZERO keywords in the FITS header.
Default is to scale, if and only if BSCALE and BZERO are
present and nontrivial.
NOUPDATE = If set, then the optional BSCALE and BZERO keywords in the
optional HEADER array will not be changed. The default is
to reset these keywords to BSCALE=1, BZERO=0. Ignored if
NOSCALE is set.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXREAD, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
NODATA = If set, then the array is not read in, but the
primary header is read.
Calls :
GET_DATE, IEEE_TO_HOST, FXADDPAR, FXHREAD, FXPAR, WHERENAN
Common :
None.
Restrictions:
Groups are not supported.
The optional parameters I1, I2, and STEP only work with one or
two-dimensional arrays. J1 and J2 only work with two-dimensional
arrays.
Use of the AVERAGE keyword is not compatible with arrays with missing
pixels.
Side effects:
If the keywords BSCALE and BZERO are present in the FITS header, and
have non-trivial values, then the returned array DATA is formed by the
equation
DATA = BSCALE*original + BZERO
However, this behavior can overridden by using the /NOSCALE keyword.
If the data is scaled, then the optional HEADER array is changed so
that BSCALE=1 and BZERO=0. This is so that these scaling parameters
are not applied to the data a second time by another routine. Also,
history records are added storing the original values of these
constants. Note that only the returned array is modified--the header
in the FITS file itself is untouched.
If the /NOUPDATE keyword is set, however, then the BSCALE and BZERO
keywords are not changed. It is then the user's responsibility to
ensure that these parameters are not reapplied to the data. In
particular, these keywords should not be present in any header when
writing another FITS file, unless the user wants their values to be
applied when the file is read back in. Otherwise, FITS readers will
read in the wrong values for the data array.
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, May 1992, based in part on READFITS by W. Landsman, and
STSUB by M. Greason and K. Venkatakrishna.
W. Thompson, Jun 1992, added code to interpret BSCALE and BZERO
records, and added NOSCALE and NOUPDATE
keywords.
W. Thompson, Aug 1992, changed to call FXHREAD, and to add history
records for BZERO, BSCALE.
Minimium IDL Version:
V5.3 (uses COMPRESS keyword to OPEN)
Written :
William Thompson, GSFC, May 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 17 November 1993.
Corrected bug with AVERAGE keyword on non-IEEE compatible
machines.
Corrected bug with subsampling on VAX machines.
Version 3, William Thompson, GSFC, 31 May 1994
Added ERRMSG keyword.
Version 4, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 5, Zarro (SAC/GSFC), 14 Feb 1997
Added I/O error checking
Version 6, 20-May-1998, David Schlegel/W. Thompson
Allow a single pixel to be read in.
Change the signal to read in the entire array to be -1
Version 7 C. Markwardt 22 Sep 2003
If the image is empty (NAXIS EQ 0), or NODATA is set, then
return only the header.
Version 8 W. Landsman 29 June 2004
Added COMPRESS keyword, check for .gz extension
Version 9, William Thompson, 19-Aug-2004
Make sure COMPRESS is treated as a scalar
Version 10, Craig Markwardt, 01 Mar 2004
Add EXTENSION keyword and ability to read different
extensions than the primary one.
Version 11, W. Landsamn September 2006
Assume since V5.5, remove VMS support
Version 11.1, W. Landsamn November 2007
Allow for possibility number of bytes requires 64 bit integer
Version 12, William Thompson, 18-Jun-2010, update BLANK value.
(See astrolib/pro/fxread.pro)
FXWRITE
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NAME:
FXWRITE
Purpose :
Write a disk FITS file.
Explanation :
Creates or appends to a disk FITS file and writes a FITS
header, and optionally an image data array.
Use :
FXWRITE, FILENAME, HEADER [, DATA ]
Inputs :
FILENAME = String containing the name of the file to be written.
HEADER = String array containing the header for the FITS file.
Opt. Inputs :
DATA = IDL data array to be written to the file. If not passed,
then it is assumed that extensions will be added to the
file.
Outputs :
None.
Opt. Outputs:
None.
Keywords :
NANVALUE = Value signalling data dropout. All points corresponding to
this value are set to be IEEE NaN (not-a-number). Ignored
unless DATA is of type float, double-precision or complex.
NOUPDATE = If set, then the optional BSCALE and BZERO keywords in the
HEADER array will not be changed. The default is to reset
these keywords to BSCALE=1, BZERO=0.
APPEND = If set, then an existing file will be appended to.
Appending to a non-existent file will create it. If
a primary HDU already exists then it will be modified
to have EXTEND = T.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned. In order to
use this feature, ERRMSG must be defined first, e.g.
ERRMSG = ''
FXWRITE, ERRMSG=ERRMSG, ...
IF ERRMSG NE '' THEN ...
Calls :
CHECK_FITS, GET_DATE, HOST_TO_IEEE, FXADDPAR, FXPAR
Common :
None.
Restrictions:
If DATA is passed, then HEADER must be consistent with it. If no data
array is being written to the file, then HEADER must also be consistent
with that. The routine FXHMAKE can be used to create a FITS header.
If found, then the optional keywords BSCALE and BZERO in the HEADER
array is changed so that BSCALE=1 and BZERO=0. This is so that these
scaling parameters are not applied to the data a second time by another
routine. Also, history records are added storing the original values
of these constants. (Other values of BZERO are used for unsigned
integers.)
If the /NOUPDATE keyword is set, however, then the BSCALE and BZERO
keywords are not changed. The user should then be aware that FITS
readers will apply these numbers to the data, even if the data is
already converted to floating point form.
Groups are not supported.
Side effects:
HEADER may be modified. One way it may be modified is describe
above under NOUPDATE. The first header card may also be
modified to conform to the FITS standard if it does not
already agree (i.e. use of either the SIMPLE or XTENSION
keyword depending on whether the image is the primary HDU or
not).
Category :
Data Handling, I/O, FITS, Generic.
Prev. Hist. :
W. Thompson, Jan 1992, from WRITEFITS by J. Woffard and W. Landsman.
Differences include:
* Made DATA array optional, and HEADER array mandatory.
* Changed order of HEADER and DATA parameters.
* No attempt made to fix HEADER array.
W. Thompson, May 1992, changed open statement to force 2880 byte fixed
length records (VMS). The software here does not
depend on this file configuration, but other
FITS readers might.
W. Thompson, Aug 1992, added code to reset BSCALE and BZERO records,
and added the NOUPDATE keyword.
Written :
William Thompson, GSFC, January 1992.
Modified :
Version 1, William Thompson, GSFC, 12 April 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 31 May 1994
Added ERRMSG keyword.
Version 3, William Thompson, GSFC, 23 June 1994
Modified so that ERRMSG is not touched if not defined.
Version 4, William Thompson, GSFC, 12 August 1999
Catch error if unable to open file.
Version 4.1 Wayne Landsman, GSFC, 02 May 2000
Remove !ERR in call to CHECK_FITS, Use ARG_PRESENT()
Version 5, William Thompson, GSFC, 22 September 2004
Recognize unsigned integer types
Version 5.1 W. Landsman 14 November 204
Allow for need for 64bit number of bytes
Version 6, Craig Markwardt, GSFC, 30 May 2005
Ability to append to existing files
Version :
Version 6, 30 May 2005
(See astrolib/pro/fxwrite.pro)
F_FORMAT
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NAME:
F_FORMAT
PURPOSE:
Choose a nice floating format for displaying an array of REAL data.
EXPLANATION:
Called by TVLIST, IMLIST.
CALLING SEQUENCE:
fmt = F_FORMAT( minval, maxval, factor, [ length ] )
INPUTS:
MINVAL - REAL scalar giving the minimum value of an array of numbers
for which one desires a nice format.
MAXVAL - REAL scalar giving maximum value in array of numbers
OPTIONAL INPUT:
LENGTH - length of the output F format (default = 5)
must be an integer scalar > 2
OUTPUT:
FMT - an F or I format string, e.g. 'F5.1'
FACTOR - factor of 10 by which to multiply array of numbers to achieve
a pretty display using format FMT.
EXAMPLE:
Find a nice format to print an array of numbers with a minimum of 5.2e-3
and a maximum of 4.2e-2.
IDL> fmt = F_FORMAT( 5.2e-3, 4.2e-2, factor )
yields fmt = '(F5.2)' and factor = .01, i.e. the array can be displayed
with a F5.2 format after multiplication by 100.
REVISION HISTORY:
Written W. Landsman December 1988
Deal with factors < 1. August 1991
Deal with factors < 1. *and* a large range October 1992
Now returns In format rather than Fn.0 February, 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/f_format.pro)
GALAGE
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NAME:
GALAGE
PURPOSE:
Determine the age of a galaxy given its redshift and a formation redshift.
CALLING SEQUENCE:
age = galage(z, [zform, H0 =, k=, lambda0 =, Omega_m= , q0 =, /SILENT])'
INPUTS:
z - positive numeric vector or scalar of measured redshifts
zform - redshift of galaxy formation (> z), numeric positive scalar
To determine the age of the universe at a given redshift, set zform
to a large number (e.g. ~1000).
OPTIONAL KEYWORD INPUTS:
H0 - Hubble constant in km/s/Mpc, positive scalar, default is 70
/SILENT - If set, then the adopted cosmological parameters are not
displayed at the terminal.
No more than two of the following four parameters should be
specified. None of them need be specified -- the adopted defaults
are given.
k - curvature constant, normalized to the closure density. Default is
0, (indicating a flat universe)
Omega_m - Matter density, normalized to the closure density, default
is 0.3. Must be non-negative
Lambda0 - Cosmological constant, normalized to the closure density,
default is 0.7
q0 - Deceleration parameter, numeric scalar = -R*(R'')/(R')^2, default
is -0.55
OUTPUTS:
age - age of galaxy in years, will have the same number of elements
as the input Z vector
EXAMPLE:
(1) Determine the age of a galaxy observed at z = 1.5 in a cosmology with
Omega_matter = 0.3 and Lambda = 0.0. Assume the formation redshift was
at z = 25, and use the default Hubble constant (=70 km/s/Mpc)
IDL> print,galage(1.5,25,Omega_m=0.3, Lambda = 0)
===> 3.35 Gyr
(2) Plot the age of a galaxy in Gyr out to a redshift of z = 5, assuming
the default cosmology (omega_m=0.3, lambda=0.7), and zform = 100
IDL> z = findgen(50)/10.
IDL> plot,z,galage(z,100)/1e9,xtit='z',ytit = 'Age (Gyr)'
PROCEDURE:
For a given formation time zform and a measured z, integrate dt/dz from
zform to z. Analytic formula of dt/dz in Gardner, PASP 110:291-305, 1998
March (eq. 7)
COMMENTS:
(1) Integrates using the IDL Astronomy Library procedure QSIMP. (The
intrinsic IDL QSIMP() function is not called because of its ridiculous
restriction that only scalar arguments can be passed to the integrating
function.) The function 'dtdz' is defined at the beginning of the
routine (so it can compile first).
(2) Should probably be fixed to use a different integrator from QSIMP when
computing age from an "infinite" redshift of formation. But using a
large value of zform seems to work adequately.
(3) An alternative set of IDL procedures for computing cosmological
parameters is available at
http://cerebus.as.arizona.edu/~ioannis/research/red/
PROCEDURES CALLED:
COSMO_PARAM, QSIMP
HISTORY:
STIS version by P. Plait (ACC) June 1999
IDL Astro Version W. Landsman (Raytheon ITSS) April 2000
Avoid integer overflow for more than 32767 redshifts July 2001
(See astrolib/pro/galage.pro)
GAL_FLAT
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NAME:
GAL_FLAT
PURPOSE:
Transforms the image of a galaxy so that the galaxy appears face-on
EXPLANATION:
Either a nearest-neighbor approximations or a bilinear interpolation
may be used.
CALLING SEQUENCE:
RESULT = GAL_FLAT( image, ang, inc, [, cen, /INTERP ] )
INPUTS:
IMAGE - Image to be transformed
ANG - Angle of major axis, counterclockwise from Y-axis, degrees
For an image in standard orientation (North up, East left)
this is the Position Angle
INC - Angle of inclination of galaxy, degrees
OPTIONAL INPUTS:
CEN - Two element vector giving the X and Y position of galaxy center
If not supplied, then the galaxy center is assumed to coincide
with the image center
INPUT KEYWORDS:
INTERP - If present, and non-zero, then bilinear interpolation will be
performed. Otherwise a nearest neighbor approximation is used.
OUTPUTS:
RESULT - the transformed image, same dimensions and type as IMAGE
METHOD:
A set of 4 equal spaced control points are corrected for inclination
using the procedure POLYWARP. These control points are used by
POLY_2D to correct the whole image.
REVISION HISTORY:
Written by R. S. Hill, SASC Technologies Inc., 4 December 1985
Code cleaned up a bit W. Landsman December 1992
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/gal_flat.pro)
GAL_UVW
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NAME:
GAL_UVW
PURPOSE:
Calculate the Galactic space velocity (U,V,W) of star
EXPLANATION:
Calculates the Galactic space velocity U, V, W of star given its
(1) coordinates, (2) proper motion, (3) distance (or parallax), and
(4) radial velocity.
CALLING SEQUENCE:
GAL_UVW, U, V, W, [/LSR, RA=, DEC=, PMRA= ,PMDEC=, VRAD= , DISTANCE=
PLX= ]
OUTPUT PARAMETERS:
U - Velocity (km/s) positive toward the Galactic *anti*center
V - Velocity (km/s) positive in the direction of Galactic rotation
W - Velocity (km/s) positive toward the North Galactic Pole
REQUIRED INPUT KEYWORDS:
User must supply a position, proper motion,radial velocity and distance
(or parallax). Either scalars or vectors can be supplied.
(1) Position:
RA - Right Ascension in *Degrees*
Dec - Declination in *Degrees*
(2) Proper Motion
PMRA = Proper motion in RA in arc units (typically milli-arcseconds/yr)
If given mu_alpha --proper motion in seconds of time/year - then
this is equal to 15*mu_alpha*cos(dec)
PMDEC = Proper motion in Declination (typically mas/yr)
(3) Radial Velocity
VRAD = radial velocity in km/s
(4) Distance or Parallax
DISTANCE - distance in parsecs
or
PLX - parallax with same distance units as proper motion measurements
typically milliarcseconds (mas)
OPTIONAL INPUT KEYWORD:
/LSR - If this keyword is set, then the output velocities will be
corrected for the solar motion (U,V,W)_Sun = (-8.5, 13.38, 6.49)
(Coskunoglu et al. 2011 MNRAS) to the local standard of rest.
Note that the value of the solar motion through the LSR remains
poorly determined.
EXAMPLE:
(1) Compute the U,V,W coordinates for the halo star HD 6755.
Use values from Hipparcos catalog, and correct to the LSR
ra = ten(1,9,42.3)*15. & dec = ten(61,32,49.5)
pmra = 628.42 & pmdec = 76.65 ;mas/yr
dis = 139 & vrad = -321.4
gal_uvw,u,v,w,ra=ra,dec=dec,pmra=pmra,pmdec=pmdec,vrad=vrad,dis=dis,/lsr
===> u=141.2 v = -491.7 w = 93.9 ;km/s
(2) Use the Hipparcos Input and Output Catalog IDL databases (see
http://idlastro.gsfc.nasa.gov/ftp/zdbase/) to obtain space velocities
for all stars within 10 pc with radial velocities > 10 km/s
dbopen,'hipp_new,hic' ;Need Hipparcos output and input catalogs
list = dbfind('plx>100,vrad>10') ;Plx > 100 mas, Vrad > 10 km/s
dbext,list,'pmra,pmdec,vrad,ra,dec,plx',pmra,pmdec,vrad,ra,dec,plx
ra = ra*15. ;Need right ascension in degrees
GAL_UVW,u,v,w,ra=ra,dec=dec,pmra=pmra,pmdec=pmdec,vrad=vrad,plx = plx
forprint,u,v,w ;Display results
METHOD:
Follows the general outline of Johnson & Soderblom (1987, AJ, 93,864)
except that U is positive outward toward the Galactic *anti*center, and
the J2000 transformation matrix to Galactic coordinates is taken from
the introduction to the Hipparcos catalog.
REVISION HISTORY:
Written, W. Landsman December 2000
fix the bug occuring if the input arrays are longer than 32767
and update the Sun velocity Sergey Koposov June 2008
vectorization of the loop -- performance on large arrays
is now 10 times higher Sergey Koposov December 2008
More recent value of solar motion WL/SK Jan 2011
(See astrolib/pro/gal_uvw.pro)
GAUSSIAN
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NAME:
GAUSSIAN
PURPOSE:
Compute the 1-d Gaussian function and optionally the derivative
EXPLANATION:
Compute the 1-D Gaussian function and optionally the derivative
at an array of points.
CALLING SEQUENCE:
y = gaussian( xi, parms,[ pderiv ])
INPUTS:
xi = array, independent variable of Gaussian function.
parms = parameters of Gaussian, 2, 3 or 4 element array:
parms[0] = maximum value (factor) of Gaussian,
parms[1] = mean value (center) of Gaussian,
parms[2] = standard deviation (sigma) of Gaussian.
(if parms has only 2 elements then sigma taken from previous
call to gaussian(), which is stored in a common block).
parms[3] = optional, constant offset added to Gaussian.
OUTPUT:
y - Function returns array of Gaussian evaluated at xi. Values will
be floating pt. (even if xi is double) unless the /DOUBLE keyword
is set.
OPTIONAL INPUT:
/DOUBLE - set this keyword to return double precision for both
the function values and (optionally) the partial derivatives.
OPTIONAL OUTPUT:
pderiv = [N,3] or [N,4] output array of partial derivatives,
computed only if parameter is present in call.
pderiv[*,i] = partial derivative at all xi absisca values
with respect to parms[i], i=0,1,2,[3].
EXAMPLE:
Evaulate a Gaussian centered at x=0, with sigma=1, and a peak value
of 10 at the points 0.5 and 1.5. Also compute the derivative
IDL> f = gaussian( [0.5,1.5], [10,0,1], DERIV )
==> f= [8.825,3.25]. DERIV will be a 2 x 3 array containing the
numerical derivative at the two points with respect to the 3 parameters.
COMMON BLOCKS:
None
HISTORY:
Written, Frank Varosi NASA/GSFC 1992.
Converted to IDL V5.0 W. Landsman September 1997
Use machar() for machine precision, added /DOUBLE keyword,
add optional constant 4th parameter W. Landsman November 2001
(See astrolib/pro/gaussian.pro)
GCIRC
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NAME:
GCIRC
PURPOSE:
Computes rigorous great circle arc distances.
EXPLANATION:
Input position can either be either radians, sexagesimal RA, Dec or
degrees. All computations are double precision.
CALLING SEQUENCE:
GCIRC, U, RA1, DC1, RA2, DC2, DIS
INPUTS:
U -- integer = 0,1, or 2: Describes units of inputs and output:
0: everything radians
1: RAx in decimal hours, DCx in decimal
degrees, DIS in arc seconds
2: RAx and DCx in degrees, DIS in arc seconds
RA1 -- Right ascension or longitude of point 1
DC1 -- Declination or latitude of point 1
RA2 -- Right ascension or longitude of point 2
DC2 -- Declination or latitude of point 2
OUTPUTS:
DIS -- Angular distance on the sky between points 1 and 2
See U above for units; double precision
PROCEDURE:
"Haversine formula" see
http://en.wikipedia.org/wiki/Great-circle_distance
NOTES:
(1) If RA1,DC1 are scalars, and RA2,DC2 are vectors, then DIS is a
vector giving the distance of each element of RA2,DC2 to RA1,DC1.
Similarly, if RA1,DC1 are vectors, and RA2, DC2 are scalars, then DIS
is a vector giving the distance of each element of RA1, DC1 to
RA2, DC2. If both RA1,DC1 and RA2,DC2 are vectors then DIS is a
vector giving the distance of each element of RA1,DC1 to the
corresponding element of RA2,DC2. If the input vectors are not the
same length, then excess elements of the longer ones will be ignored.
(2) The function SPHDIST provides an alternate method of computing
a spherical distance.
(3) The haversine formula can give rounding errors for antipodal
points.
PROCEDURE CALLS:
None
MODIFICATION HISTORY:
Written in Fortran by R. Hill -- SASC Technologies -- January 3, 1986
Translated from FORTRAN to IDL, RSH, STX, 2/6/87
Vector arguments allowed W. Landsman April 1989
Prints result if last argument not given. RSH, RSTX, 3 Apr. 1998
Remove ISARRAY(), V5.1 version W. Landsman August 2000
Added option U=2 W. Landsman October 2006
Use double precision for U=0 as advertised R. McMahon/W.L. April 2007
Use havesine formula, which has less roundoff error in the
milliarcsecond regime W.L. Mar 2009
(See astrolib/pro/gcirc.pro)
GCNTRD
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NAME:
GCNTRD
PURPOSE:
Compute the stellar centroid by Gaussian fits to marginal X,Y, sums
EXPLANATION:
GCNTRD uses the DAOPHOT "FIND" centroid algorithm by fitting Gaussians
to the marginal X,Y distributions. User can specify bad pixels
(either by using the MAXGOOD keyword or setting them to NaN) to be
ignored in the fit. Pixel values are weighted toward the center to
avoid contamination by neighboring stars.
CALLING SEQUENCE:
GCNTRD, img, x, y, xcen, ycen, [ fwhm , /SILENT, /DEBUG, MAXGOOD = ,
/KEEPCENTER ]
INPUTS:
IMG - Two dimensional image array
X,Y - Scalar or vector integers giving approximate stellar center
OPTIONAL INPUT:
FWHM - floating scalar; Centroid is computed using a box of half
width equal to 1.5 sigma = 0.637* FWHM. GCNTRD will prompt
for FWHM if not supplied
OUTPUTS:
XCEN - the computed X centroid position, same number of points as X
YCEN - computed Y centroid position, same number of points as Y
Values for XCEN and YCEN will not be computed if the computed
centroid falls outside of the box, or if there are too many bad pixels,
or if the best-fit Gaussian has a negative height. If the centroid
cannot be computed, then a message is displayed (unless /SILENT is
set) and XCEN and YCEN are set to -1.
OPTIONAL OUTPUT KEYWORDS:
MAXGOOD= Only pixels with values less than MAXGOOD are used to in
Gaussian fits to determine the centroid. For non-integer
data, one can also flag bad pixels using NaN values.
/SILENT - Normally GCNTRD prints an error message if it is unable
to compute the centroid. Set /SILENT to suppress this.
/DEBUG - If this keyword is set, then GCNTRD will display the subarray
it is using to compute the centroid.
/KeepCenter By default, GCNTRD first convolves a small region around
the supplied position with a lowered Gaussian filter, and then
finds the maximum pixel in a box centered on the input X,Y
coordinates, and then extracts a new box about this maximum
pixel. Set the /KeepCenter keyword to skip the convolution
and finding the maximum pixel, and instead use a box
centered on the input X,Y coordinates.
PROCEDURE:
Unless /KEEPCENTER is set, a small area around the initial X,Y is
convolved with a Gaussian kernel, and the maximum pixel is found.
This pixel is used as the center of a square, within
which the centroid is computed as the Gaussian least-squares fit
to the marginal sums in the X and Y directions.
EXAMPLE:
Find the centroid of a star in an image im, with approximate center
631, 48. Assume that bad (saturated) pixels have a value of 4096 or
or higher, and that the approximate FWHM is 3 pixels.
IDL> GCNTRD, IM, 631, 48, XCEN, YCEN, 3, MAXGOOD = 4096
MODIFICATION HISTORY:
Written June 2004, W. Landsman following algorithm used by P. Stetson
in DAOPHOT2.
Modified centroid computation (as in IRAF/DAOFIND) to allow shifts of
more than 1 pixel from initial guess. March 2008
First perform Gaussian convolution prior to finding maximum pixel
to smooth out noise W. Landsman Jan 2009
(See astrolib/pro/gcntrd.pro)
GEO2ECI
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NAME:
GEO2ECI
PURPOSE:
Convert geographic spherical coordinates to Earth-centered inertial coords
EXPLANATION:
Converts from geographic spherical coordinates [latitude, longitude,
altitude] to ECI (Earth-Centered Inertial) [X,Y,Z] rectangular
coordinates. JD time is also needed.
Geographic coordinates are in degrees/degrees/km
Geographic coordinates assume the Earth is a perfect sphere, with radius
equal to its equatorial radius.
ECI coordinates are in km from Earth center.
CALLING SEQUENCE:
ECIcoord=geo2eci(gcoord,JDtime)
INPUT:
gcoord: geographic [latitude,longitude,altitude], or a an array [3,n]
of n such coordinates
JDtime: Julian Day time, double precision. Can be a 1-D array of n
such times.
KEYWORD INPUTS:
None
OUTPUT:
a 3-element array of ECI [X,Y,Z] coordinates, or an array [3,n] of
n such coordinates, double precision
COMMON BLOCKS:
None
PROCEDURES USED:
CT2LST - Convert Local Civil Time to Local Mean Sidereal Time
EXAMPLES:
IDL> ECIcoord=geo2eci([0,0,0], 2452343.38982663D)
IDL> print,ECIcoord
-3902.9606 5044.5548 0.0000000
(The above is the ECI coordinates of the intersection of the equator and
Greenwich's meridian on 2002/03/09 21:21:21.021)
MODIFICATION HISTORY:
Written by Pascal Saint-Hilaire ([email protected])
on 2002/05/14
(See astrolib/pro/geo2eci.pro)
GEO2GEODETIC
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NAME:
GEO2GEODETIC
PURPOSE:
Convert from geographic/planetographic to geodetic coordinates
EXPLANATION:
Converts from geographic (latitude, longitude, altitude) to geodetic
(latitude, longitude, altitude). In geographic coordinates, the
Earth is assumed a perfect sphere with a radius equal to its equatorial
radius. The geodetic (or ellipsoidal) coordinate system takes into
account the Earth's oblateness.
Geographic and geodetic longitudes are identical.
Geodetic latitude is the angle between local zenith and the equatorial plane.
Geographic and geodetic altitudes are both the closest distance between
the satellite and the ground.
The PLANET keyword allows a similar transformation for the other
planets (planetographic to planetodetic coordinates).
The EQUATORIAL_RADIUS and POLAR_RADIUS keywords allow the
transformation for any ellipsoid.
Latitudes and longitudes are expressed in degrees, altitudes in km.
REF: Stephen P. Keeler and Yves Nievergelt, "Computing geodetic
coordinates", SIAM Rev. Vol. 40, No. 2, pp. 300-309, June 1998
Planetary constants from "Allen's Astrophysical Quantities",
Fourth Ed., (2000)
CALLING SEQUENCE:
ecoord=geo2geodetic(gcoord,[ PLANET=,EQUATORIAL_RADIUS=, POLAR_RADIUS=])
INPUT:
gcoord = a 3-element array of geographic [latitude,longitude,altitude],
or an array [3,n] of n such coordinates.
OPTIONAL KEYWORD INPUT:
PLANET = keyword specifying planet (default is Earth). The planet
may be specified either as an integer (1-9) or as one of the
(case-independent) strings 'mercury','venus','earth','mars',
'jupiter','saturn','uranus','neptune', or 'pluto'
EQUATORIAL_RADIUS : Self-explanatory. In km. If not set, PLANET's
value is used.
POLAR_RADIUS : Self-explanatory. In km. If not set, PLANET's value is
used.
OUTPUT:
a 3-element array of geodetic/planetodetic [latitude,longitude,altitude],
or an array [3,n] of n such coordinates, double precision.
COMMON BLOCKS:
None
RESTRICTIONS:
Whereas the conversion from geodetic to geographic coordinates is given
by an exact, analytical formula, the conversion from geographic to
geodetic isn't. Approximative iterations (as used here) exist, but tend
to become less good with increasing eccentricity and altitude.
The formula used in this routine should give correct results within
six digits for all spatial locations, for an ellipsoid (planet) with
an eccentricity similar to or less than Earth's.
More accurate results can be obtained via calculus, needing a
non-determined amount of iterations.
In any case,
IDL> PRINT,geodetic2geo(geo2geodetic(gcoord)) - gcoord
is a pretty good way to evaluate the accuracy of geo2geodetic.pro.
EXAMPLES:
Locate the geographic North pole, altitude 0., in geodetic coordinates
IDL> geo=[90.d0,0.d0,0.d0]
IDL> geod=geo2geodetic(geo); convert to equivalent geodetic coordinates
IDL> PRINT,geod
90.000000 0.0000000 21.385000
As above, but for the case of Mars
IDL> geod=geo2geodetic(geo,PLANET='Mars')
IDL> PRINT,geod
90.000000 0.0000000 18.235500
MODIFICATION HISTORY:
Written by Pascal Saint-Hilaire ([email protected]), May 2002
Generalized for all solar system planets by Robert L. Marcialis
([email protected]), May 2002
Modified 2002/05/18, PSH: added keywords EQUATORIAL_RADIUS and
POLAR_RADIUS
(See astrolib/pro/geo2geodetic.pro)
GEO2MAG()
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NAME:
GEO2MAG()
PURPOSE:
Convert from geographic to geomagnetic coordinates
EXPLANATION:
Converts from GEOGRAPHIC (latitude,longitude) to GEOMAGNETIC (latitude,
longitude). (Altitude remains the same)
Latitudes and longitudes are expressed in degrees.
CALLING SEQUENCE:
mcoord=geo2mag(gcoord)
INPUT:
gcoord = a 2-element array of geographic [latitude,longitude], or an
array [2,n] of n such coordinates.
KEYWORD INPUTS:
None
OUTPUT:
a 2-element array of magnetic [latitude,longitude], or an array [2,n]
of n such coordinates
COMMON BLOCKS:
None
EXAMPLES:
geographic coordinates of magnetic south pole
IDL> mcoord=geo2mag([79.3,288.59])
IDL> print,mcoord
89.999992 -173.02325
MODIFICATION HISTORY:
Written by Pascal Saint-Hilaire ([email protected]),
May 2002
(See astrolib/pro/geo2mag.pro)
GEODETIC2GEO
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NAME:
GEODETIC2GEO
PURPOSE:
Convert from geodetic (or planetodetic) to geographic coordinates
EXPLANATION:
Converts from geodetic (latitude, longitude, altitude) to geographic
(latitude, longitude, altitude). In geographic coordinates, the
Earth is assumed a perfect sphere with a radius equal to its equatorial
radius. The geodetic (or ellipsoidal) coordinate system takes into
account the Earth's oblateness.
Geographic and geodetic longitudes are identical.
Geodetic latitude is the angle between local zenith and the equatorial
plane. Geographic and geodetic altitudes are both the closest distance
between the satellite and the ground.
The PLANET keyword allows a similar transformation for the other
planets (planetodetic to planetographic coordinates).
The EQUATORIAL_RADIUS and POLAR_RADIUS keywords allow the
transformation for any ellipsoid.
Latitudes and longitudes are expressed in degrees, altitudes in km.
REF: Stephen P. Keeler and Yves Nievergelt, "Computing geodetic
coordinates", SIAM Rev. Vol. 40, No. 2, pp. 300-309, June 1998
Planetary constants from "Allen's Astrophysical Quantities",
Fourth Ed., (2000)
CALLING SEQUENCE:
gcoord = geodetic2geo(ecoord, [ PLANET= ] )
INPUT:
ecoord = a 3-element array of geodetic [latitude,longitude,altitude],
or an array [3,n] of n such coordinates.
OPTIONAL KEYWORD INPUT:
PLANET = keyword specifying planet (default is Earth). The planet
may be specified either as an integer (1-9) or as one of the
(case-independent) strings 'mercury','venus','earth','mars',
'jupiter','saturn','uranus','neptune', or 'pluto'
EQUATORIAL_RADIUS : Self-explanatory. In km. If not set, PLANET's value
is used. Numeric scalar
POLAR_RADIUS : Self-explanatory. In km. If not set, PLANET's value is
used. Numeric scalar
OUTPUT:
a 3-element array of geographic [latitude,longitude,altitude], or an
array [3,n] of n such coordinates, double precision
The geographic and geodetic longitudes will be identical.
COMMON BLOCKS:
None
EXAMPLES:
IDL> geod=[90,0,0] ; North pole, altitude 0., in geodetic coordinates
IDL> geo=geodetic2geo(geod)
IDL> PRINT,geo
90.000000 0.0000000 -21.385000
As above, but the equivalent planetographic coordinates for Mars
IDL> geod=geodetic2geo(geod,PLANET='Mars');
IDL> PRINT,geod
90.000000 0.0000000 -18.235500
MODIFICATION HISTORY:
Written by Pascal Saint-Hilaire ([email protected]),
May 2002
Generalized for all solar system planets by Robert L. Marcialis
([email protected]), May 2002
Modified 2002/05/18, PSH: added keywords EQUATORIAL_RADIUS and
POLAR_RADIUS
(See astrolib/pro/geodetic2geo.pro)
GETOPT
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NAME:
GETOPT
PURPOSE:
Convert a string supplied by the user into a valid scalar or vector
EXPLANATION:
Distinct elements in the string may be
separated by either a comma or a space. The output scalar
or vector can be specified to be either integer or floating
point. A null string is converted to a zero.
CALLING SEQUENCE:
option = GETOPT( input, [ type, numopt, COUNT = ])
INPUTS:
input - string that was input by user in response to a prompt
Arithmetic operations can be included in the string (see
examples)
OPTIONAL INPUTS:
type - Either an "I" (integer) or an "F" (floating point) specifying
the datatype of the output vector. Default is floating point
numopt - number of values expected by calling procedure
If less than NUMOPT values are supplied the output
vector will be padded with zeros.
OUTPUTS:
option - scalar or vector containing the numeric conversion of
the fields in the string INPUT. If NUMOPT is not
supplied, the number of elements in OPTION will
equal the number of distinct fields in INPUT.
OPTIONAL INPUT KEYWORD:
Count - integer giving the number of values actually returned by
GETOPT. If the input is invalid then COUNT is set to -1
NOTES:
(1) If an input is invalid, Count is set to -1 and the result is set
to 999.
(2) GETOPT uses the execute function to interpret the user string.
Therefore GETOPT itself cannot be called with the EXECUTE
function.
(3) GETOPT has a hard limit of 10 tokens in the input string.
EXAMPLES:
(1) a = getopt( '3.4,5*4 ', 'I' ) yields a = [ 3, 20]
(2) a = getopt( '5/2.', 'F', 5) yields a = [2.5,0.,0.,0.,0.]
(3) a = getopt( '2*3,5,6') yields a = [6.,5.,6.]
REVISON HISTORY:
written by B. Pfarr, STX, 5/6/87
change value of !ERR W. Landsman STX, 6/30/88
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/getopt.pro)
GETPRO
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NAME:
GETPRO
PURPOSE:
Search !PATH for a procedure, and copy into user's working directory
EXPLANATION:
Extract a procedure from an IDL Library or directory given in the
!PATH system variable and place it in the current default directory
(presumably to be edited by the user).
CALLING SEQUENCE:
GETPRO, [ proc_name ] ;Find PROC_NAME in !PATH and copy
OPTIONAL INPUT:
proc_name - Character string giving the name of the IDL procedure or
function. Do not give an extension. If omitted,
the program will prompt for PROC_NAME.
OUTPUTS:
None.
SIDE EFFECTS:
A file with the extension .pro and a name given by PROC_NAME will
be created on the user's directory.
PROCEDURE:
The FILE_WHICH() function is used to locate the procedure in the IDL
!PATH. When found, FILE_COPY is used to
copy the procedure into the user's current default directory. If not
found in !PATH, then the ROUTINE_INFO() function is used to determine
if it is an intrinsic IDL procedure.
EXAMPLE:
Put a copy of the USER library procedure CURVEFIT on the current
directory
IDL> getpro, 'CURVEFIT'
RESTRICTIONS:
User will be unable to obain source code for a native IDL function
or procedure, or for a FORTRAN or C routine added with CALL_EXTERNAL.
User must have write privilege to the current directory
PROCEDURE CALLS:
ZPARCHECK
REVISION HISTORY:
Written W. Landsman, STX Corp. June 1990
Now use intrinsic EXPAND_PATH() command W. Landsman November 1994
Use ROUTINE_NAMES() to check for intrinsic procs W. Landsman July 95
Update for Windows/IDL W. Landsman September 95
Check if procedure is in current directory W. Landsman June 1997
Use ROUTINE_INFO instead of undocumented ROUTINE_NAMES W.L. October 1998
Use FILE_WHICH() to locate procedure W. Landsman May 2006
Assume since V5.5, remove VMS support W. Landsman Sep 2006
Assume since V6.0, use file_basename() W.Landsman Feb 2009
Test for .sav file, more robust test for write privilege W.L. Jul 2010
(See astrolib/pro/getpro.pro)
GETPSF
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NAME:
GETPSF
PURPOSE:
To generate a point-spread function (PSF) from observed stars.
EXPLANATION:
The PSF is represented as a 2-dimensional Gaussian
(integrated over each pixel) and a lookup table of residuals.
The lookup table and Gaussian parameters are output in a FITS
image file. The PSF FITS file created by GETPSF can be
read with the procedure RDPSF. Adapted from the 1986 STSDAS
version of DAOPHOT
CALLING SEQUENCE:
GETPSF, image, xc, yc, apmag, sky, [ronois, phpadu, gauss, psf,
idpsf, psfrad, fitrad, psfname, /DEBUG ]
INPUTS:
IMAGE - input image array
XC - input vector of x coordinates (from FIND), these should be
IDL (first pixel is (0,0)) convention.
YC - input vector of y coordinates (from FIND)
APMAG - vector of magnitudes (from APER), used for initial estimate
of gaussian intensity. If APMAG is multidimensional, (more
than 1 aperture was used in APER) then the first aperture
is used.
SKY - vector of sky values (from APER)
OPTIONAL INPUTS:
The user will be prompted for the following parameters if not supplied.
RONOIS - readout noise per pixel, (in electrons, or equivalent photons)
PHPADU - photons per analog digital unit, used to scale the data
numbers in IMAGE into photon units
IDPSF - subscripts of the list of stars created by
APER which will be used to define the PSF. Stars whose
centroid does not fall within PSFRAD of the edge of the frame,
or for which a Gaussian fit requires more than 25 iterations,
will be ignored when creating the final PSF.
PSFRAD - the scalar radius, in pixels, of the circular area within
which the PSF will be defined. This should be slightly larger
than the radius of the brightest star that one will be
interested in.
FITRAD - the scalar radius, in pixels of the circular area used in the
least-square star fits. Stetson suggest that FITRAD should
approximately equal to the FWHM, slightly less for crowded
fields. (FITRAD must be smaller than PSFRAD.)
PSFNAME- Name of the FITS file that will contain the table of residuals,
and the best-fit Gaussian parameters. This file is
subsequently required for use by NSTAR.
OPTIONAL OUTPUTS:
GAUSS - 5 element vector giving parameters of gaussian fit to the
first PSF star
GAUSS(0) - height of the gaussian (above sky)
GAUSS(1) - the offset (in pixels) of the best fitting gaussian
and the original X centroid
GAUSS(2) - similiar offset from the Y centroid
GAUSS(3) - Gaussian sigma in X
GAUSS(4) - Gaussian sigma in Y
PSF - 2-d array of PSF residuals after a Gaussian fit.
PROCEDURE:
GETPSF fits a Gaussian profile to the core of the first PSF star
and generates a look-up table of the residuals of the
actual image data from the Gaussian fit. If desired, it will then
fit this PSF to another star (using PKFIT) to determine its precise
centroid, scale the same Gaussian to the new star's core, and add the
differences between the actual data and the scaled Gaussian to the
table of residuals. (In other words, the Gaussian fit is performed
only on the first star.)
OPTIONAL KEYWORD INPUT:
DEBUG - if this keyword is set and non-zero, then the result of each
fitting iteration will be displayed.
PROCEDURES CALLED
DAOERF, MAKE_2D, MKHDR, RINTER(), PKFIT, STRNUMBER(), STRN(), WRITEFITS
REVISON HISTORY:
Adapted from the 1986 version of DAOPHOT in STSDAS
IDL Version 2 W Landsman November 1988
Use DEBUG keyword instead of !DEBUG W. Landsman May 1996
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/getpsf.pro)
GETROT
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NAME:
GETROT
PURPOSE:
Return the rotation and plate scale of an image from its FITS header
EXPLANATION:
Derive the counterclockwise rotation angle, and the X and Y scale
factors of an image, from a FITS image header. The input parameter
may be either a FITS image header or an astrometry structure (as
obtained by extast.pro)
CALLING SEQUENCE:
GETROT, Hdr, [ Rot, CDelt, /SILENT, DEBUG = ]
or
GETROT, Astr, Rot, CDelt, /SILENT, DEBUG = ]
INPUT PARAMETERS:
HDR - FITS Image header (string array). Program will extract the
astrometry structure
or
ASTR - ASTROMETRY structure, of the type returned by EXTAST.
See the documentation for EXTAST.PRO for details.
OPTIONAL OUTPUT PARAMETERS:
ROT - Scalar giving the counterclockwise rotation of NORTH in DEGREES
from the +Y axis of the image.
CDELT- 2 element vector giving the scale factors in DEGREES/PIXEL in
the X and Y directions. CDELT[1] is always positive, whereas
CDELT[0] is negative for a normal left-handed coordinate system,
and positive for a right-handed system.
If no output variables are supplied (or /DEBUG is set), then GETROT
will display the rotation and plate scale at the terminal.
OPTIONAL INPUT KEYWORD
ALT - single character 'A' through 'Z' or ' ' specifying an alternate
astrometry system present in the FITS header. See extast.pro
for more information on the ALT keyword. Ignored if an
astrometry structure rather than FITS header is supplied.
DEBUG - if DEBUG is set, GETROT will print the rotation for both the
X and Y axis when these values are unequal. If DEBUG is set to 2,
then the output parameter ROT will contain both X and Y rotations.
/SILENT - if set, then do not provide a warning about a right-handed
coordinate system
PROCEDURE:
If the FITS header already contains CDELT (and CD or CROTA) keyword,
(as suggested by the Calabretta & Greisen (2002, A&A, 395, 1077) FITS
standard) then this is used for the scale factor.
If the header contains CD keywords but no CDELT keywords (as in IRAF
headers) then the scale factor is derived from the CD matrix.
In case of skew (different rotations of the X and Y axes), the rotations
are averaged together if they are less than 2 degrees. Otherwise,
a warning is given and the X rotation is used.
PROCEDURES USED:
EXTAST, GSSS_EXTAST
REVISION HISTORY:
Written W. Landsman STX January 1987
Option to return both rotations added. J. D. Offenberg, STX, Aug 1991
Use new astrometry structure W. Landsman Mar 1994
Recognize a GSSS header W. Landsman June 1994
Correct rotation determination with unequal CDELT values WL October 1998
Consistent conversion between CROTA and CD matrix WL October 2000
Correct CDELT computations for rotations near 90 deg WL November 2002
Preserve sign in the CDELT output WL June 2003
Check if latitude/longitude reversed in CTYPE WL February 2004
Fix problem in latitude check M.Lombardi/W.Landsman Sep 2004
Added ALT keyword W. Landsman May 2005
Account for any rotation of the native system by examining the value
of LONGPOLE H. Taylor/W. Landsman
Account for case where X,Y rotations differ by 2*!pi WL. Aug 2011
(See astrolib/pro/getrot.pro)
GETTOK
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NAME:
GETTOK
PURPOSE:
Retrieve the first part of a (vector) string up to a specified character
EXPLANATION:
GET TOKen - Retrieve first part of string until the character char
is encountered.
CALLING SEQUENCE:
token = gettok( st, char, [ /EXACT, /NOTRIM ] )
INPUT:
char - character separating tokens, scalar string
INPUT-OUTPUT:
st - string to get token from (on output token is removed unless
/NOTRIM is set), scalar or vector
OUTPUT:
token - extracted string value is returned, same dimensions as st
OPTIONAL INPUT KEYWORD:
/EXACT - The default behaviour of GETTOK is to remove any leading
blanks and (if the token is a blank) convert tabs to blanks.
Set the /EXACT keyword to skip these steps and leave the
input string unchanged before searching for the character
tokens.
/NOTRIM - if set, then the input string is left unaltered
EXAMPLE:
If ST is ['abc=999','x=3.4234'] then gettok(ST,'=') would return
['abc','x'] and ST would be left as ['999','3.4234']
PROCEDURE CALLS:
REPCHR()
HISTORY
version 1 by D. Lindler APR,86
Remove leading blanks W. Landsman (from JKF) Aug. 1991
V5.3 version, accept vector input W. Landsman February 2000
Slightly faster implementation W. Landsman February 2001
Added EXACT keyword W. Landsman March 2004
Assume since V5.4, Use COMPLEMENT keyword to WHERE W. Landsman Apr 2006
Added NOTRIM keyword W. L. March 2011
(See astrolib/pro/gettok.pro)
GET_COORDS
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NAME:
GET_COORDS
PURPOSE:
Converts a string with angular coordinates to floating point values.
EXPLANATION:
Although called by ASTRO.PRO, this is a general purpose routine.
The user may input as floating point or sexagesimal. If user inputs
calling procedure's job to convert hours to degrees if needed.
Since the input string is parsed character-by-character, ANY character
that is not a digit, minus sign or decimal point may be used as a
delimiter, i.e. acceptable examples of user input are:
1:03:55 -10:15:31
1 3 55.0 -10 15 31
1*3 55 -10abcd15efghij31
1.065278 hello -10.25861
CALLING SEQUENCE:
GET_COORDS, Coords, [ PromptString, NumVals, INSTRING =, /QUIET ]
OPTIONAL INPUT:
PromptString - A string to inform the user what data are to be entered
OPTIONAL KEYWORD INPUT:
InString - a keyword that, if set, is assumed to already contain the
input data string to be parsed. If this keyword is set, then
the user is not prompted for any input.
/Quiet - if set the program won't printout any error messages, but bad
input is still flagged by Coords=[-999,-999].
OUTPUT:
Coords - a 2 element floating array containing the coordinates. The
vector [-999,-999] is returned if there has been an error.
OPTIONAL OUTPUT:
NumVals - the number of separate values entered by the user: 2 if the
user entered the coordinates as floating point numbers, 6 if
the user entered the coordinates as sexagesimal numbers. Some
calling procedures might find this information useful (e.g., to
to print some output in the same format as the user's input).
REVISION HISTORY:
Written by Joel Parker, 5 MAR 90
Included InString and Quiet keywords. Cleaned up some of the code and
comments. JWmP, 16 Jun 94
*******************************************************************************
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/get_coords.pro)
GET_DATE
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NAME:
GET_DATE
PURPOSE:
Return the (current) UTC date in CCYY-MM-DD format for FITS headers
EXPLANATION:
This is the format required by the DATE and DATE-OBS keywords in a
FITS header.
CALLING SEQUENCE:
GET_DATE, FITS_date, [ in_date, /OLD, /TIMETAG ]
OPTIONAL INPUTS:
in_date - string (scalar or vector) containing dates in IDL
systime() format (e.g. 'Tue Sep 25 14:56:14 2001')
OUTPUTS:
FITS_date = A scalar character string giving the current date. Actual
appearance of dte depends on which keywords are supplied.
No Keywords supplied - dte is a 10 character string with the format
CCYY-MM-DD where represents a calendar year, the
ordinal number of a calendar month within the calendar year,
and the ordinal number of a day within the calendar month.
/TIMETAG set - dte is a 19 character string with the format
CCYY-MM-DDThh:mm:ss where represents the hour in the day,
the minutes, the seconds, and the literal 'T' the
ISO 8601 time designator
/OLD set - dte is an 8 character string in DD/MM/YY format
INPUT KEYWORDS:
/TIMETAG - Specify the time to the nearest second in the DATE format
/OLD - Return the DATE format formerly (pre-1997) recommended for FITS
Note that this format is now deprecated because it uses only
a 2 digit representation of the year.
EXAMPLE:
Add the current date to the DATE keyword in a FITS header,h
IDL> GET_DATE,dte
IDL> sxaddpar, h, 'DATE', dte, 'Date header was created'
NOTES:
(1) A discussion of the DATExxx syntax in FITS headers can be found in
http://www.cv.nrao.edu/fits/documents/standards/year2000.txt
(2) Those who wish to use need further flexibility in their date
formats (e.g. to use TAI time) should look at Bill Thompson's time
routines in http://sohowww.nascom.nasa.gov/solarsoft/gen/idl/time
PROCEDURES USED:
DAYCNV - Convert Julian date to Gregorian calendar date
REVISION HISTORY:
Written W. Landsman March 1991
Major rewrite to write new DATExxx syntax W. Landsman August 1997
Converted to IDL V5.0 W. Landsman September 1997
Work after year 2000 even with /OLD keyword W. Landsman January 2000
Don't need to worry about TIME_DIFF since V5.4 W. Landsman July 2001
Assume since V5.4, remove LOCAL_DIFF keyword W. Landsman April 2006
(See astrolib/pro/get_date.pro)
GET_EQUINOX
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NAME:
GET_EQUINOX
PURPOSE:
Return the equinox value from a FITS header.
EXPLANATION:
Checks for 4 possibilities:
(1) If the EQUINOX keyword is found and has a numeric value, then this
value is returned
(2) If the EQUINOX keyword has the values 'J2000' or 'B1950', then
either 2000. or 1950. is returned.
(3) If the EQUINOX keyword is not found, then GET_EQUINOX will return
the EPOCH keyword value. This usage of EPOCH is disparaged.
(4) If neither EQUINOX no EPOCH is found, then the RADESYS keyword
(or the deprecated RADECSYS keyword) is checked. If the value
is 'ICRS' or 'FK5' then 2000 is is returned, if it is 'FK4' then
1950 is returned.
According Calabretta & Greisen (2002, A&A, 395, 1077) the EQUINOX should
be written as a numeric value, as in format (1). However, in older
FITS headers, the EQUINOX might have been written using formats (2) or
(3).
CALLING SEQUENCE:
Year = GET_EQUINOX( Hdr, [ Code ] )
INPUTS:
Hdr - FITS Header, string array, will be searched for the EQUINOX
(or EPOCH) keyword.
OUTPUT:
Year - Year of equinox in FITS header, numeric scalar
OPTIONAL OUTPUT:
Code - Result of header search, scalar
-1 - EQUINOX, EPOCH or RADECSYS keyword not found in header
0 - EQUINOX found as a numeric value
1 - EPOCH keyword used for equinox (not recommended)
2 - EQUINOX found as 'B1950'
3 - EQUINOX found as 'J2000'
4 - EQUINOX derived from value of RADESYS or RADECSYS keyword
'ICRS', 'FK5' ==> 2000, 'FK4' ==> 1950
OPTIONAL KEYWORD INPUT:
ALT - single character 'A' through 'Z' or ' ' specifying which
astrometry system to use in the FITS header. The default is
to use the primary astrometry or ALT = ''. If /ALT is set,
then this is equivalent to ALT = 'A'. See Section 3.3 of
Greisen & Calabretta (2002, A&A, 395, 1061) for information about
alternate astrometry keywords.
PROCEDURES USED:
ZPARCHECK, SXPAR()
NOTES:
Technically, RADESYS = 'ICRS' does not specify any equinox, but can be
assumed to be equivalent to J2000 for all but highest-precision work.
REVISION HISTORY:
Written W. Landsman STX March, 1991
Don't use !ERR W. Landsman February 2000
N = 1 for check of EPOCH keyword, not 0 S. Ott July 2000
Added ALT keyword, recognize RADESYS along with deprecated RADECSYS
W. Landsman Sep 2011
(See astrolib/pro/get_equinox.pro)
GET_JULDATE
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NAME:
GET_JULDATE
PURPOSE:
Return the current Julian Date
EXPLANATION:
In V5.4, GET_JULDATE became completely obsolete with the introduction
of the /UTC keyword to SYSTIME(). So GET_JULDATE,jd is equivalent to
jd = SYSTIME(/JULIAN,/UTC).
CALLING SEQUENCE:
GET_JULDATE,jd
INPUTS:
None
OUTPUTS:
jd = Current Julian Date, double precision scalar
EXAMPLE:
Return the current hour, day, month and year as integers
IDL> GET_JULDATE, JD ;Get current Julian date
IDL> DAYCNV, JD, YR, MON, DAY, HOURS ;Convert to hour,day month & year
METHOD:
A call is made to SYSTIME(/JULIAN,/UTC).
REVISION HISTORY:
Written Wayne Landsman March, 1991
Converted to IDL V5.0 W. Landsman September 1997
Assume since V5.4 Use /UTC keyword to SYSTIME() W. Landsman April 2006
(See astrolib/pro/get_juldate.pro)
GLACTC
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NAME:
GLACTC
PURPOSE:
Convert between celestial and Galactic (or Supergalactic) coordinates.
EXPLANATION:
Program to convert right ascension (ra) and declination (dec) to
Galactic longitude (gl) and latitude (gb) (j=1) or vice versa (j=2).
CALLING SEQUENCE:
GLACTC, ra, dec, year, gl, gb, j, [ /DEGREE, /FK4, /SuperGalactic ]
INPUT PARAMETERS:
year equinox of ra and dec, scalar (input)
j direction of conversion (input)
1: ra,dec --> gl,gb
2: gl,gb --> ra,dec
INPUTS OR OUTPUT PARAMETERS: ( depending on argument J )
ra Right ascension, hours (or degrees if /DEGREES is set),
scalar or vector
dec Declination, degrees,scalar or vector
gl Galactic longitude, degrees, scalar or vector
gb Galactic latitude, degrees, scalar or vector
All results forced double precision floating.
OPTIONAL INPUT KEYWORD PARAMETERS:
/DEGREE - If set, then the RA parameter (both input and output) is
given in degrees rather than hours.
/FK4 - If set, then the celestial (RA, Dec) coordinates are assumed
to be input/output in the FK4 system. By default, coordinates
are assumed to be in the FK5 system. For B1950 coordinates,
set the /FK4 keyword *and* set the year to 1950.
/SuperGalactic - If set, the GLACTC returns SuperGalactic coordinates
as defined by deVaucouleurs et al. (1976) to account for the
local supercluster. The North pole in SuperGalactic coordinates
has Galactic coordinates l = 47.47, b = 6.32, and the origin is
at Galactic coordinates l = 137.37, b= 0
EXAMPLES:
Find the Galactic coordinates of Altair (RA (J2000): 19 50 47
Dec (J2000): 08 52 06)
IDL> glactc, ten(19,50,47),ten(8,52,6),2000,gl,gb,1
==> gl = 47.74, gb = -8.91
PROCEDURE CALLS:
BPRECESS, JPRECESS, PRECESS
HISTORY:
FORTRAN subroutine by T. A. Nagy, 21-MAR-78.
Conversion to IDL, R. S. Hill, STX, 19-OCT-87.
Modified to handle vector input, E. P. Smith, GSFC, 14-OCT-94
Converted to IDL V5.0 W. Landsman September 1997
Added DEGREE keyword, C. Markwardt, Nov 1999
Major rewrite, default now FK5 coordinates, added /FK4 keyword
use external precession routines W. Landsman April 2002
Add /Supergalactic keyword W. Landsman September 2002
Fix major bug when year not 2000 and /FK4 not set W. Landsman July 2003
(See astrolib/pro/glactc.pro)
GLACTC_PM
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NAME:
GLACTC_PM
PURPOSE:
Convert between celestial and Galactic (or Supergalactic) proper
motion (also converts coordinates).
EXPLANATION:
Program to convert proper motion in equatorial coordinates (ra,dec)
to proper motion in Galactic coordinates (gl, gb) or Supergalacic
Coordinates (sgl,sgb) or back to equatorial coordinates (j=2).
The proper motion unit is arbitrary, but be sure to set /MUSTAR if
units are the projection of the proper motion on the RA, Dec axis.
It does precession on the coordinates but does not
take care of precession of the proper motions which is usually a
very small effect.
CALLING SEQUENCE:
GLACTC_PM, ra, dec, mu_ra,mu_dec,year, gl, gb, mu_gl, mu_gb, j,
[ /DEGREE, /FK4, /SuperGalactic, /mustar ]
INPUT PARAMETERS:
year equinox of ra and dec, scalar (input)
j direction of conversion (input)
1: ra,dec,mu_ra,mu_dec --> gl,gb,mu_gl,mu_gb
2: gl,gb,mu_gl,mu_gb --> ra,dec,mu_ra,mu_dec
INPUTS OR OUTPUT PARAMETERS: ( depending on argument J )
ra Right ascension, hours (or degrees if /DEGREES is set),
scalar or vector.
dec Declination, degrees,scalar or vector
mu_ra right ascension proper motion any proper motion unit
(angle/time)
mu_dec declination proper motion in any proper motion unit
(angle/time)
gl Galactic longitude, degrees, scalar or vector
gb Galactic latitude, degrees, scalar or vector
mu_gl galactic longitude proper motion in any time unit
mu_gb galactic latitude proper motion in any time unit
All results forced double precision floating.
OPTIONAL INPUT KEYWORD PARAMETERS:
/DEGREE - If set, then the RA parameter (both input and output) is
given in degrees rather than hours.
/FK4 - If set, then the celestial (RA, Dec) coordinates are assumed
to be input/output in the FK4 system. By default, coordinates
are assumed to be in the FK5 system. For B1950 coordinates,
set the /FK4 keyword *and* set the year to 1950.
/SuperGalactic - If set, the GLACTC returns SuperGalactic coordinates
as defined by deVaucouleurs et al. (1976) to account for the
local supercluster. The North pole in SuperGalactic coordinates
has Galactic coordinates l = 47.47, b = 6.32, and the origin is
at Galactic coordinates l = 137.37, b= 0
/mustar - if set then input and output of mu_ra and mu_dec are the
projections of mu in the ra or dec direction rather than
the d(ra)/dt or d(mu)/dt. So mu_ra becomes mu_ra*cos(dec)
and mu_gl becomes mu_gl*cos(gb).
EXAMPLES:
Find the SuperGalactic proper motion of M33 given its
equatorial proper motion mu* =(-29.3, 45.2) microas/yr.
Where the (*) indicates ra component is actual mu_ra*cos(dec)
(Position: RA (J2000): 01 33 50.9, Dec (J2000): 30 39 36.8)
IDL> glactc_pm, ten(1,33,50.9),ten(30,39,36.8),-29.3,45.2, 2000,$
sgl,sgb,mu_sgl,mu_sgb,1,/Supergalactic,/mustar
==> SGL = 328.46732 deg, SGB = -0.089896901 deg,
mu_sgl = 33.732 muas/yr, mu_gb = 41.996 muas/yr.
And for the roundtrip:
IDL> glactc_pm, ra,dec,mu_ra,mu_dec,2000,$
IDL> sgl,sgb,mu_sgl,mu_sgb,2,/Supergalactic,/mustar
==> ra=1.5641376 hrs., dec= 30.660277 deg,
mu_ra= -29.300000 muas/yr, mu_dec=i 45.200000 muas/yr
PROCEDURE CALLS:
BPRECESS, JPRECESS, PRECESS
HISTORY:
Written Ed Shaya, U of MD, Oct 2009.
Adapted from GLACTC to make proper motion transformations,
Correct occasional sign error in galactic longitude E. Shaya Nov 2011
(See astrolib/pro/glactc_pm.pro)
GROUP
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NAME:
GROUP
PURPOSE:
Assign stars with non-overlapping PSF profiles into distinct groups
EXPLANATION:
Part of the IDL-DAOPHOT sequence
CALLING SEQUENCE:
GROUP, X, Y, RCRIT, NGROUP
INPUTS:
X - vector, giving X coordinates of a set of stars.
Y - vector, giving Y coordinates of a set of stars.
If X and Y are input as integers, then they will be converted to
floating point
RCRIT - scalar, giving minimum distance between stars of two
distinct groups. Stars less than this distance from
each other are always in the same group. Stetson suggests
setting the critical distance equal to the PSF radius +
the Fitting radius.
OUTPUTS:
NGROUP - integer vector, same number of elements as X and Y,
giving a group number for each star position. Group
numbering begins with 0.
METHOD:
Each position is initially given a unique group number. The distance
of each star is computed against every other star. Those distances
less than RCRIT are assigned the minimum group number of the set. A
check is then made to see if any groups have merged together.
PROCEDURES USED:
REM_DUP()
REVISION HISTORY:
Written W. Landsman STX April, 1988
Major revision to properly merge groups together W. Landsman Sep 1991
Work for more than 32767 points W. Landsman March 1997
Converted to IDL V5.0 W. Landsman September 1997
Avoid overflow if X and Y are integers W. Landsman Feb. 1999
(See astrolib/pro/group.pro)
GSSSADXY
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NAME:
GSSSADXY
PURPOSE:
Converts RA and DEC (J2000) to (X,Y) for an STScI GuideStar image.
EXPLANATION:
The sky coordinates may be printed and/or returned in variables.
CALLING SEQUENCE:
GSSSADXY, GSA, Ra,Dec, [ X, Y, /Print ]
INPUT:
GSA - the GSSS Astrometry structure created by GSSSEXTAST
RA - the RA coordinate(s) in *degrees*, scalar or vector
DEC - the DEC coordinate(s) in *degrees*, scalar or vector
OPTIONAL KEYWORD INPUT:
/PRINT - If this keyword is set and non-zero, then coordinates will be
displayed at the terminal
OUTPUT:
X - the corresponding X pixel coordinate(s), double precision
Y - the corresponding Y pixel coordinate(s), double precision
X and Y will be in IDL convention (first pixel 0,0)
EXAMPLE:
Given a FITS header, hdr, from the STScI Guidestar Survey, determine
the X,Y coordinates of 3C 273 (RA = 12 29 6.7 +02 03 08)
IDL> GSSSEXTAST, hdr, gsa ;Extract astrometry structure
IDL> GSSSADXY, gsa, ten(12,29,6.7)*15,ten(2,3,8),/print
NOTES:
For most purpose users can simply use ADXY, which will call GSSSADXY
if it is passed a GSSS header.
PROCEDURES CALLED:
ASTDISP - Print RA, Dec in standard format
HISTORY:
10-JUL-90 Version 1 written by Eric W. Deutsch
Derived from procedures written by Brian McLean
Vectorized code W. Landsman March, 1991
14-AUG-91 Fixed error which caused returned X and Y to be .5 pixels too
large. Now X,Y follows same protocol as ADXY.
June 1994 - Dropped PRFLAG parameter, added /PRINT W. Landsman (HSTX)
Converted to IDL V5.0 W. Landsman September 1997
29-JUN-99 Added support for AMD[X,Y]1[2-3] for DSS images by E. Deutsch
Reduce memory requirements for large arrays D. Finkbeiner April 2004
(See astrolib/pro/gsssadxy.pro)
GSSSEXTAST
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NAME:
GSSSEXTAST
PURPOSE:
Extract IDL astrometry structure from a ST Guide Star Survey FITS header
EXPLANATION:
This procedure extracts the astrometry information from a ST Guide
Star Survey FITS header and places it in an IDL structure for
subsequent use with GSSSxyad and GSSSadxy.
CALLING SEQUENCE:
GSSSExtast, hdr, astr, noparams
INPUT:
h - the GSSS FITS header
OUTPUT:
astr - Structure containing the GSSS Astrometry information
.CTYPE = ['RA---GSS','DEC--GSS']
.CRVAL = plate center Ra, Dec (from PLTRAH, PLTRAM etc.)
.XLL,.YLL = offsets lower lefthand corner
.AMDX, .AMDY = 12 transformation coefficients
.XSZ,.YSZ = X and Y pixel size in microns
.PLTSCL = plate scale in arc sec/mm
.PPO3, .PPO6 - orientation coefficients
NOTES:
Most users should use EXTAST rather than this procedure. EXTAST will
call GSSSEXTAST if supplied with GSSS FITS header.
PROCEDURES CALLED:
SXPAR() - Extract parameter values from a FITS header
HISTORY:
01-JUL-90 Version 1 written by Eric W. Deutsch
Code derived from Software by Brian McLean
20-AUG-91 Modified to Double Precision Variables. E. Deutsch
June 94 Change astrometry tags to better agree with EXTAST W. Landsman
Converted to IDL V5.0 W. Landsman September 1997
29-JUN-99 Added support for AMD[X,Y]1[2-3] for DSS images by E. Deutsch
Eliminate use of obsolete !ERR W. Landsman February 2000
(See astrolib/pro/gsssextast.pro)
GSSSXYAD
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NAME:
GSSSXYAD
PURPOSE:
Convert (X,Y) coordinates in a STScI Guide Star image to RA and Dec
EXPLANATION:
The sky coordinates may be printed and/or returned in variables.
CALLING SEQUENCE:
GSSSxyad, gsa, x, y, ra, dec, [ /PRINT ]
INPUT:
GSA - The GSSS Astrometry structure extracted from a FITS header
by GSSSEXTAST
X - The X pixel coordinate(s) of the image, scalar or vector
Y - The Y pixel coordinate(s) of the image, scalar or vector
OUTPUT:
RA - The RA coordinate of the given pixel(s) in *degrees*
DEC - The DEC coordinate of the given pixel(s) in *degrees*
Both RA and Dec will be returned as double precision
OPTIONAL KEYWORD INPUT:
/PRINT - If this keyword is set and non-zero, then coordinates will be
displayed at the terminal
EXAMPLE:
Given a FITS header,hdr, from a GSSS image, print the astronomical
coordinates of (X,Y) = (200.23, 100.16) at the terminal
IDL> GSSSExtast, hdr, gsa ;Extract astrometry structure
IDL> GSSSxyad, gsa, 200.23, 100.16, /print
NOTES:
For most purpose users can simply use XYAD, which will call GSSSXYAD
if it is passed a GSSS header.
PROCEDURES CALLED:
ASTDISP - print RA, Dec in a standard format
HISTORY:
01-JUL-90 Version 1 written by Eric W. Deutsch
Vectorized Code W. Landsman March, 1991
14-AUG-91 Fixed error which caused returned RA and DEC to be off by
-.5 pixels in both X,Y. Now X,Y follows same protocol as ADXY.
20-AUG-91 Modified to use AstDisp procedure.
June 94 Added /PRINT keyword instead of PRFLAG W. Landsman June 94
Converted to IDL V5.0 W. Landsman September 1997
29-JUN-99 Added support for AMD[X,Y]1[2-3] for DSS images by E. Deutsch
(See astrolib/pro/gsssxyad.pro)
GSSS_STDAST
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NAME:
GSSS_STDAST
PURPOSE:
Insert the closest tangent projection astrometry into an GSSS Image
DESCRIPTION:
This procedure takes a header with GSSS (ST Guide Star Survey)
astrometry and writes a roughly equivalent tangent projection
astrometry into the header. One might want to do this if (1)
one needs to use software which does not recognize the GSSS astrometric
parameters or (2) if the the image to be transformed, since the
highly nonlinear GSSS solution does not transform easily.
CALLING SEQUENCE:
GSSS_STDAST, H, [Xpts, Ypts]
INPUT - OUTPUT:
H - FITS header (string array) containing GSSS astrometry.
GSSS_STDAST will write the roughly equivalent tangent projection
astrometry solution into H.
OPTIONAL INPUTS:
xpts, ypts -- Vectors giving the X and Y positions of the three
reference points used to find approximate tangent projection.
Default is Xpts = [0.2,0.8,0.5], Ypts = [0.2, 0.4, 0.8]
METHOD:
The procedures GSSSXYAD is used to exactly determine the RA and Dec
at 3 reference points. STARAST is then used to find the tangent
projection astrometry that best matches these reference points.
NOTES:
Images from the STScI server (http://archive.stsci.edu/dss/) contain
both a GSSS polynomial plate solution and an approximate WCS tangent
projection. The value of the WCSNAME keyword in the FITS header
is 'DSS'. If WCSNAME = "DSS' then the more accurate DSS astrometry
is extracted by EXTAST This procedure changes the value of WCSNAME
to 'DSS_TANGENT' to indicate that the tangent solution should be used.
Some early GSSS images (before the 1994 CD-Rom) used keywords CRPIXx
rather than CNPIXx. The GSSS astrometry in these images could be
corrupted by this procedure as the CRPIXx values will be altered.
The tangent is only a approximation of the nonlinear GSSS astrometry,
but is generally accurate to about 0.1 pixels on a 1024 x 1024 image.
PROCEDURES USED:
GSSSEXTAST, GSSSXYAD, STARAST, PUTAST, SXADDHIST, SXDELPAR
HISTORY:
13-AUG-91 Version 2 written from MAKEASTGSSS Eric Deutsch (STScI)
Delete CDELT* keywords from header W. Landsman May 1994
Remove call to BUILDAST W. Landsman Jan, 1995
Added optional Xpts, Ypts parameters E. Deutsch Oct, 1995
Add WCSNAME W. Landsman Nov 2006
(See astrolib/pro/gsss_stdast.pro)
HADEC2ALTAZ
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NAME:
HADEC2ALTAZ
PURPOSE:
Converts Hour Angle and Declination to Horizon (alt-az) coordinates.
EXPLANATION:
Can deal with NCP/SCP singularity. Intended mainly to be used by
program EQ2HOR
CALLING SEQUENCE:
HADEC2ALTAZ, ha, dec, lat ,alt ,az [ /WS ]
INPUTS
ha - the local apparent hour angle, in DEGREES, scalar or vector
dec - the local apparent declination, in DEGREES, scalar or vector
lat - the local latitude, in DEGREES, scalar or vector
OUTPUTS
alt - the local apparent altitude, in DEGREES.
az - the local apparent azimuth, in DEGREES, all results in double
precision
OPTIONAL KEYWORD INPUT:
/WS - Set this keyword for the output azimuth to be measured West from
South. The default is to measure azimuth East from North.
EXAMPLE:
What were the apparent altitude and azimuth of the sun when it transited
the local meridian at Pine Bluff Observatory (Lat=+43.07833 degrees) on
April 21, 2002? An object transits the local meridian at 0 hour angle.
Assume this will happen at roughly 1 PM local time (18:00 UTC).
IDL> jdcnv, 2002, 4, 21, 18., jd ; get rough Julian date to determine
;Sun ra, dec.
IDL> sunpos, jd, ra, dec
IDL> hadec2altaz, 0., dec, 43.078333, alt, az
===> Altitude alt = 58.90
Azimuth az = 180.0
REVISION HISTORY:
Written Chris O'Dell Univ. of Wisconsin-Madison May 2002
(See astrolib/pro/hadec2altaz.pro)
HASTROM
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NAME:
HASTROM
PURPOSE:
Transformation of an image to align it with a reference image
EXPLANATION:
A transformation is applied (using POLY_2D) to an image so that
its astrometry is identical with that in a reference header. This
procedure can be used to align two images.
CALLING SEQUENCE:
HASTROM, oldim, oldhd, newim, newhd, refhd, [MISSING =, INTERP = ]
or
HASTROM, oldim, oldhd, refhd, [MISSING =, INTERP ={0,1,2}, NGRID =,
CUBIC =, DEGREE = ]
INPUTS:
OLDIM - Image array to be manipulated. If only 3 parameters are
supplied then OLDIM and OLDHD will be modified to contain
the output image array and header
OLDHD - FITS header array for OLDIM, containing astrometry parameters
REFHD - Reference header, containing astrometry parameters. OLDIM
will be rotated, shifted, and compressed or expanded until
its astrometry matches that in REFHD.
OUTPUTS:
NEWIM - Image array after transformation has been performed.
The dimensions of NEWIM will be identical to the NAXIS1 and
NAXIS2 keywords specified in REFHD. Regions on the reference
image that do not exist in OLDIM can be assigned a value with
the MISSING keyword.
NEWHD - Updated FITS image header associated with NEWIM
OPTIONAL INPUT KEYWORDS:
MISSING - Set this keyword to a scalar value which will be assigned
to pixels in the output image which are out of range of the
supplied imput image. If not supplied, then linear
extrapolation is used. See the IDL manual on POLY_2D.
***NOTE: A bug was introduced into the POLY_2D function in IDL
V5.5 (fixed in V6.1) such that the MISSING keyword
may not work properly with floating point data***
INTERP - Scalar, one of 0, 1, or 2 determining type of interpolation
0 nearest neighbor, 1 (default) bilinear interpolation,
2 cubic interpolation.
CUBIC - a scalar value between -1 and 0 specifying cubic interpolation
with the specified value as the cubic interpolation parameter.
(see poly_2d for info). Setting CUBIC to a value greater
than zero is equivalent to setting CUBIC = -1.
NGRID - Integer scalar specifying the number of equally spaced grid
points on each axis to use to specify the transformation.
The value of NGRID must always be greater than DEGREE + 1.
The default is DEGREE + 2 which equals 3 (9 total points) for
DEGREE=1 (linear warping).
DEGREE - Integer scalar specifying the degree of the transformation.
See the routine POLYWARP for more info. Default =
1 (linear transformation) unless polynomial ('SIP') distortion
parameters are present in either the input or reference FITS
header. In that case, the default degree is equal to the
degree of the distortion polynomial.
OPTIONAL OUTPUT KEYWORD:
ERRMSG - If this keyword is supplied, then any error messages will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
NOTES:
(1) The 3 parameter calling sequence is less demanding on virtual
memory.
(2) The astrometry in OLDHD will be precessed to match the equinox
given in REFHD.
(3) If an ST Guidestar image is used for the reference header, then the
output header will be converted to standard astrometry.
EXAMPLE:
Suppose one has an image array, IM, and an associated FITS header H.
One desires to warp the image array so that it is aligned with another
image with a FITS header, HREF. Both headers contain astrometry info.
Set pixel values to 0 where there is no overlap between the input and
reference image, and use linear interpolation (default)
IDL> hastrom, IM, H, HREF, MISSING = 0
PROCEDURES USED:
ad2xy, check_FITS, extast, get_EQUINOX(), gsssextast, hprecess,
putast, sxaddpar, sxaddhist, sxpar(), xy2ad, zparcheck
REVISION HISTORY:
Written W. Landsman, STX Co. Feb, 1989
Updated to CHECK_FITS Dec, 1991
New astrometry keywords Mar, 1994
Recognize GSSS header W. Landsman June, 1994
Added CUBIC keyword W. Landsman March, 1997
Accept INTERP=0, Convert output GSS header to standard astrometry
W. Landsman June 1998
Remove calls to obsolete !ERR system variable March 2000
Added ERRMSG output keyword W. Landsman April 2000
Need to re-extract astrometry after precession W. Landsman Nov. 2000
Check for distortion parameters in headers, add more FITS HISTORY
information W. Landsman February 2005
Use different coefficient for nearest neighbor to avoid half-pixel
shift with POLY_2D W. Landsman Aug 2006
Return ERRMSG if no overlap between images W. Landsman Nov 2007
Use V6.0 notation W. Landsman Jan 2012
(See astrolib/pro/hastrom.pro)
HBOXAVE
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NAME:
HBOXAVE
PURPOSE:
Box average an image array and update the FITS header array
EXPLANATION:
The function BOXAVE() is used. This procedure is recommended for
integer images when photometric precision is desired, because it
performs intermediate steps using REAL*4 arithmetic. Otherwise, the
procedure HREBIN is much faster.
CALLING SEQUENCE:
HBOXAVE, Oldim, Oldhd, Newim, Hewhd, box
or
HBOXAVE, Oldim, Oldhd, box
INPUTS:
Oldim - the original image array
Oldhd - the original image FITS header, string array
OPTIONAL INPUTS:
box - the box size to be used, integer scalar. If omitted, then
HBOXAVE will prompt for this parameter.
OPTIONAL OUTPUTS:
Newim - the image after boxaveraging
Newhd - header for newim containing updated astrometry info
If output parameters are not supplied, the program
will modify the input parameters OLDIM and OLDHD
to contain the new array and updated header.
OPTIONAL KEYWORD OUTPUT:
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
PROCEDURE:
The parameters BSCALE, NAXIS1, NAXIS2, CRPIX1, and CRPIX2 and
the CD (or CDELT) parameters are updated for the new FITS header.
EXAMPLE:
Compress the image in a FITS file 'image.fits' by a factor of 4 and
update the astrometry in the FITS header
IDL> im = readfits('image.fits',hdr) ;Read FITS file into IDL arrays
IDL> hboxave, im, hdr, 4 ;Boxaverage by 4
IDL> writefits,'image.fits',im,hdr ;Write a new FITS file
CALLED PROCEDURES:
CHECK_FITS - Check that the FITS header is appropriate to the image
BOXAVE() - Performs box averaging of an image
SXPAR(), SXADDPAR - Read and write FITS keyword values
MODIFICATION HISTORY:
Written, Aug. 1986 W. Landsman, STI Corp.
IDLV2 changes, sxaddpar format keyword added, J. Isensee, July,1990
Fix 0.5 pixel offset in new CRPIX computation W. Landsman, Dec, 1991
Update BSCALE even if no astrometry present W. Landsman, May 1997
Added ERRMSG keyword, Use double formatting W. Landsman April 2000
Recognize PC matrix astrometry format W. Landsman December 2001
Use V6.0 notation W. Landsman October 2012
(See astrolib/pro/hboxave.pro)
HCONGRID
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NAME:
HCONGRID
PURPOSE:
CONGRID an image and update astrometry in a FITS header
EXPLANATION:
Expand or contract an image using CONGRID and update the
associated FITS header array.
CALLING SEQUENCE:
HCONGRID, oldhd ;Update FITS header only
HCONGRID, oldim, oldhd, [ newim, newhd, newx, newy, /HALF_HALF
CUBIC = , INTERP=, OUTSIZE=, ERRMSG=, ALT= ]
INPUTS:
OLDIM - the original image array
OLDHD - the original image FITS header, string array
OPTIONAL INPUTS:
NEWX - size of the new image in the X direction
NEWY - size of the new image in the Y direction
The OUTSIZE keyword can be used instead of the
NEWX, NEWY parameters
OPTIONAL OUTPUTS:
NEWIM - the image after expansion or contraction with CONGRID
NEWHD - header for newim containing updated astrometry info
If output parameters are not supplied, the program
will modify the input parameters OLDIM and OLDHD
to contain the new array and updated header.
OPTIONAL KEYWORD INPUTS:
ALT - Single character 'A' through 'Z' or ' ' specifying which astrometry
system to modify in the FITS header. The default is to use the
primary astrometry of ALT = ' '. See Greisen and Calabretta (2002)
for information about alternate astrometry keywords.
CUBIC - If set and non-zero, then cubic interpolation is used. Valid
ranges are -1 <= Cubic < 0. Setting /CUBIC is equivalent to
CUBIC = -1 and also equivalent to INTERP = 2. See INTERPOLATE
for more info. Setting CUBIC = -0.5 is recommended.
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
/HALF_HALF - Due to edge effects, the default behaviour of CONGRID is
to introduce a slight shift in the image center. Craig Markwardt
(http://cow.physics.wisc.edu/~craigm/idl/misc.html) has written
a modified version of CONGRID called CMCONGRID that when used with
the /HALF_HALF keyword eliminates any shift. The use of the
/HALF keyword emulates CMCONGRID and eliminates any shift in the
image centroid.
INTERP - 0 for nearest neighbor, 1 for bilinear interpolation
(default), 2 for cubic (=-1) interpolation.
OUTSIZE - Two element integer vector which can be used instead of the
NEWX and NEWY parameters to specify the output image dimensions
OPTIONAL KEYWORD OUTPUT:
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
PROCEDURE:
Expansion or contraction is done using the CONGRID function, unless
HALF_HALF is set.
The parameters BSCALE, NAXIS1, NAXIS2, CRPIX1, and CRPIX2 and
the CD (or CDELT) parameters are updated for the new header.
NOTES:
A FITS header can be supplied as the first parameter without having
to supply an image array. The astrometry in the FITS header will be
updated to be appropriate to the specified image size.
If the FITS header contains astrometry from a ST Guide Star image,
then the astrometry will be converted to an approximately equivalent
tangent projection before applying CONGRID.
EXAMPLE:
Congrid an 512 x 512 image array IM and FITS header H to size 300 x 300
using cubic interpolation. Use the HALF_HALF keyword to avoid
a shift of the image centroid
IDL> hcongrid, IM ,H, OUT = [300, 300], CUBIC = -0.5, /HALF
The variables IM and H will be modified to the new image size.
PROCEDURES CALLED:
CHECK_FITS, CONGRID(), EXTAST, GSSS_STDAST, SXADDHIST,
SXADDPAR, SXPAR(), ZPARCHECK
MODIFICATION HISTORY:
Written, Aug. 1986 W. Landsman, STI Corp.
Added interp keywords, J. Isensee, July, 1990
Add cubic interpolation W. Landsman HSTX January 1994
Recognize a GSSS FITS header W. Landsman June 1994
Fix case where header but not image supplied W. Landsman May 1995
Remove call to SINCE_VERSION() W. Landsman March 1996
Assume since IDL V3.5, add CUBIC keyword W. Landsman March 1997
Update BSCALE even if no astrometry present W. Landsman May 1997
Converted to IDL V5.0 W. Landsman September 1997
Added HALF_HALF keyword W. Landsman February 2000
Added ERRMSG keyword, use double precision formatting W.L. April 2000
Recognize PC00n00m astrometry format W. Landsman December 2001
Now works when both /INTERP and /HALF are set W. Landsman January 2002
Fix output astrometry for non-equal plate scales for PC matrix or
CROTA2 keyword, added ALT keyword. W. Landsman May 2005
Update distortion parameters if present W. Landsman January 2008
Don't update BSCALE/BZERO for unsigned integer W.Landsman Mar 2008
Write CRPIX as Double precision if necessary W. Landsman Oct 2012
(See astrolib/pro/hcongrid.pro)
HEADFITS
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NAME:
HEADFITS
PURPOSE:
Read a FITS (primary or extension) header into a string array.
EXPLANATION:
HEADFITS() supports several types of compressed files including
gzip (.gz), Unix compressed (.Z), Bzip2 (.bz2) or FPACK (.fz
http://heasarc.gsfc.nasa.gov/fitsio/fpack/ )
CALLING SEQUENCE:
Result = HEADFITS(Filename/Fileunit ,[ ERRMSG =, EXTEN= , COMPRESS=,
/SILENT ])
INPUTS:
Filename = String containing the name of the FITS file to be read.
If set to an empty string, then user will be prompted for name.
File names ending in '.gz' are assumed to be gzip'ed compressed
and under Unix file names ending in '.Z' are assumed to be
Unix compressed, and file names ending in .bz2 are assumed to
be bzip2 compressed. If this default behaviour is not
sufficient then use the COMPRESS keyword.
or
Fileunit - A scalar integer specifying the unit of an already opened
FITS file. The unit will remain open after exiting
HEADFITS(). There are two possible reasons for choosing
to specify a unit number rather than a file name:
(1) For a FITS file with many extensions, one can move to the
desired extensions with FXPOSIT() and then use HEADFITS(). This
is more efficient that repeatedly starting at the beginning of
the file.
(2) For reading a FITS file across a Web http: address after opening
the unit with the SOCKET procedure.
OPTIONAL INPUT KEYWORDS:
EXTEN = Either an integer scalar, specifying which FITS extension to
read, or a scalar string specifying the extension name (stored
in the EXTNAME keyword). For example, to read the header of
the first extension set EXTEN = 1. Default is to read the
primary FITS header (EXTEN = 0). The EXTEN keyword cannot
be used when a unit number is supplied instead of a file name.
COMPRESS - If this keyword is set and non-zero, then treat the file
as compressed. If 1 assume a gzipped file. Use IDL's
internal decompression facilities for gzip files, while for
Unix or bzip2 compression spawn off a process to decompress and
use its output as the FITS stream. If the keyword is not 1,
then use its value as a string giving the command needed for
decompression. See FXPOSIT for more info.
/SILENT - If set, then suppress any warning messages about invalid
characters in the FITS file.
OPTIONAL KEYWORD OUTPUT:
ERRMSG = If this keyword is present, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned.
OUTPUTS:
Result of function = FITS header, string array
EXAMPLE:
Print the main FITS header of a file 'test.fits' into a string
variable, h
IDL> print, headfits( 'test.fits')
Print the second extension header of a gzip compressed FITS file
'test.fits.gz'. Use HPRINT for pretty format
IDL> hprint, headfits( 'test.fits.gz', ext=2)
Read the extension named CALSPEC
IDL> hprint,headfits('test.fits.gz',ext='CALSPEC')
PROCEDURES CALLED
FXPOSIT(), MRD_HREAD
The version of fxposit.pro must be post- May 2009.
MODIFICATION HISTORY:
adapted by Frank Varosi from READFITS by Jim Wofford, January, 24 1989
Keyword EXTEN added, K.Venkatakrishna, May 1992
Make sure first 8 characters are 'SIMPLE' W. Landsman October 1993
Check PCOUNT and GCOUNT W. Landsman December 1994
Major rewrite, work for Unix gzip files, W. Landsman April 1996
Added COMPRESS keyword W. Landsman April 2000
Added ERRMSG keyword W. Landsman July 2000
Added /SILENT keyword W. Landsman December 2000
Option to read a unit number rather than file name W.L October 2001
Test output status of MRD_HREAD call October 2003 W. Landsman
Allow extension to be specified by name Dec 2006 W. Landsman
No need to uncompress FPACK compressed files May 2009 W. Landsman
Use V6.0 notation W.L. Feb. 2011
(See astrolib/pro/headfits.pro)
HELIO
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NAME:
HELIO
PURPOSE:
Compute (low-precision) heliocentric coordinates for the planets.
EXPLANATION:
The mean orbital elements for epoch J2000 are used. These are derived
from a 250 yr least squares fit of the DE 200 planetary ephemeris to a
Keplerian orbit where each element is allowed to vary linearly with
time. For dates between 1800 and 2050, this solution fits the
terrestrial planet orbits to ~25" or better, but achieves only ~600"
for Saturn.
Use PLANET_COORDS (which calls HELIO) to get celestial (RA, Dec)
coordinates of the planets
CALLING SEQUENCE:
HELIO, JD, LIST, HRAD, HLONG, HLAT, [/RADIAN]
INPUTS:
JD = Julian date, double precision scalar or vector
LIST = List of planets array. May be a single number.
1 = merc, 2 = venus, ... 9 = pluto.
OUTPUTS:
HRAD = array of Heliocentric radii (A.U).
HLONG = array of Heliocentric (ecliptic) longitudes (degrees).
HLAT = array of Heliocentric latitudes (degrees).
These output parameters will be dimensioned Nplanet by Ndate,
where Nplanet is the number of elements of list, and Ndate is
the number of elements of JD.
OPTIONAL INPUT KEYWORD:
/RADIAN - If set, then the output longitude and latitude are given in
radians.
EXAMPLE:
(1) Find the current heliocentric positions of all the planets
IDL> GET_JULDATE, jd ;Get current Julian date
IDL> HELIO,jd,indgen(9)+1,hrad,hlong,hlat ;Get radius, long, and lat
(2) Find heliocentric position of Mars on August 23, 2000
IDL> JDCNV, 2000,08,23,0,jd
IDL> HELIO,JD,2,HRAD,HLONG,HLAT
===> hrad = 1.6407 AU hlong = 124.3197 hlat = 1.7853
For comparison, the JPL ephemeris gives
hrad = 1.6407 AU hlong = 124.2985 hlat = 1.7845
(3) Find the heliocentric positions of Mars and Venus for every day in
November 2000
IDL> JDCNV, 2000, 11, 1, 0, jd ;Julian date of November 1, 2000
IDL> helio, jd+indgen(30), [4,2], hrad,hlong,hlat ;Mars=4, Venus=2
hrad, hlong, and hlat will be dimensioned [2,30]
first column contains Mars data, second column Venus
COMMON BLOCKS:
None
ROUTINES USED:
CIRRANGE - force angle between 0 and 2*!PI
NOTES:
(1) The calling sequence for this procedure was changed in August 2000
(2) This program is based on the two-body model and thus neglects
interactions between the planets. This is why the worst results
are for Saturn. Use the procedure JPLEPHINTERp for more accurate
positions using the JPL ephemeris. Also see
http://ssd.jpl.nasa.gov/cgi-bin/eph for a more accurate ephemeris
generator online.
(3) The coordinates are given for equinox 2000 and *not* the equinox
of the supplied date(s)
MODIFICATION HISTORY:
R. Sterner. 20 Aug, 1986.
Code cleaned up a bit W. Landsman December 1992
Major rewrite, use modern orbital elements, vectorize, more accurate
solution to Kepler's equation W. Landsman August 2000
Wasn't working for planet vectors W. Landsman August 2000
Work for more than 32767 positions S. Leach Jan 2009
(See astrolib/pro/helio.pro)
HELIO_JD
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NAME:
HELIO_JD
PURPOSE:
Convert geocentric (reduced) Julian date to heliocentric Julian date
EXPLANATION:
This procedure correct for the extra light travel time between the Earth
and the Sun.
An online calculator for this quantity is available at
http://www.physics.sfasu.edu/astro/javascript/hjd.html
Users requiring more precise calculations and documentation should
look at the IDL code available at
http://astroutils.astronomy.ohio-state.edu/time/
CALLING SEQUENCE:
jdhelio = HELIO_JD( date, ra, dec, /B1950, /TIME_DIFF)
INPUTS
date - reduced Julian date (= JD - 2400000), scalar or vector, MUST
be double precision
ra,dec - scalars giving right ascension and declination in DEGREES
Equinox is J2000 unless the /B1950 keyword is set
OUTPUTS:
jdhelio - heliocentric reduced Julian date. If /TIME_DIFF is set, then
HELIO_JD() instead returns the time difference in seconds
between the geocentric and heliocentric Julian date.
OPTIONAL INPUT KEYWORDS
/B1950 - if set, then input coordinates are assumed to be in equinox
B1950 coordinates.
/TIME_DIFF - if set, then HELIO_JD() returns the time difference
(heliocentric JD - geocentric JD ) in seconds
EXAMPLE:
What is the heliocentric Julian date of an observation of V402 Cygni
(J2000: RA = 20 9 7.8, Dec = 37 09 07) taken June 15, 1973 at 11:40 UT?
IDL> juldate, [1973,6,15,11,40], jd ;Get geocentric Julian date
IDL> hjd = helio_jd( jd, ten(20,9,7.8)*15., ten(37,9,7) )
==> hjd = 41848.9881
Wayne Warren (Raytheon ITSS) has compared the results of HELIO_JD with the
FORTRAN subroutines in the STARLINK SLALIB library (see
http://star-www.rl.ac.uk/).
Time Diff (sec)
Date RA(2000) Dec(2000) STARLINK IDL
1999-10-29T00:00:00.0 21 08 25. -67 22 00. -59.0 -59.0
1999-10-29T00:00:00.0 02 56 33.4 +00 26 55. 474.1 474.1
1940-12-11T06:55:00.0 07 34 41.9 -00 30 42. 366.3 370.2
1992-02-29T03:15:56.2 12 56 27.4 +42 10 17. 350.8 350.9
2000-03-01T10:26:31.8 14 28 36.7 -20 42 11. 243.7 243.7
2100-02-26T09:18:24.2 08 26 51.7 +85 47 28. 104.0 108.8
PROCEDURES CALLED:
bprecess, xyz, zparcheck
REVISION HISTORY:
Algorithm from the book Astronomical Photometry by Henden, p. 114
Written, W. Landsman STX June, 1989
Make J2000 default equinox, add B1950, /TIME_DIFF keywords, compute
variation of the obliquity W. Landsman November 1999
(See astrolib/pro/helio_jd.pro)
HELIO_RV
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NAME:
HELIO_RV
PURPOSE:
Return the heliocentric radial velocity of a spectroscopic binary
EXPLANATION:
This function will return the heliocentric radial velocity of a
spectroscopic binary star at a given heliocentric date
given its orbit.
CALLING SEQUENCE:
Result = HELIO_RV ( JD ,T ,Period ,Gamma , K, [,e ,Omega ] )
INPUT:
JD - Time of observation
T - Time of periastron passage (max. +ve velocity
for circular orbits), same time system as JD
Period - the period in same units as JD
Gamma - systemic velocity
K - velocity semi-amplitude in the same units as Gamma.
e - eccentricity of the orbit, default is 0.
Omega - longitude of periastron in degrees. Must be specified for
eccentric orbits.
OUTPUT:
The predicted heliocentric radial velocity in the same units as Gamma
for the date(s) specified by Reduced_HJD.
RESTRICTIONS:
The user should ensure consistency with all time systems being
used (i.e. JD and T should be in the same units and time system).
Generally, users should reduce large time values by subtracting
a large constant offset, which may improve numerical accuracy.
If using the the routines JULDATE and HELIO_JD, the reduced HJD
time system must be used throughtout.
EXAMPLES:
Example 1
What was the heliocentric radial velocity of the primary component of HU Tau
at 1730 UT 25 Oct 1994?
IDL> juldate ,[94,10,25,17,30],JD ;Get Geocentric julian date
IDL> hjd = helio_jd(jd,ten(04,38,16)*15.,ten(20,41,05)) ; Convert to HJD
IDL> print, helio_rv(hjd,46487.5303D,2.0563056D,-6.0,59.3)
-62.965569
NB. 1. The routines JULDATE and HELIO_JD return a reduced HJD (HJD - 2400000)
and so T and P must be specified in the same fashion.
2. The user should be careful to use double precision format to specify
T and P to sufficient precision where necessary.
Example 2
Plot two cycles of an eccentric orbit, e=0.6, omega=45 for both
components of a binary star
IDL> phi=findgen(100)/50.0 ; Generates 100 phase points
IDL> plot, phi,helio_rv(phi,0,1,0,100,0.6,45),yrange=[-100,150]
IDL> oplot, phi,helio_rv(phi,0,1,0,50,0.6,45+180)
This illustrates both the use of arrays to perform multiple calculations
and generating radial velocities for a given phase by setting T=0 and P=1.
Note also that omega has been changed by 180 degrees for the orbit of the
second component (the same 'trick' can be used for circular orbits).
MODIFICATION HISTORY:
Written by: Pierre Maxted CUOBS, October, 1994
Circular orbits handled by setting e=0 and omega=0 to allow
binary orbits to be handled using omega and omega+180.
Pierre Maxted,Feb 95
BUG - omega was altered by the routine - corrected Feb 95,Pierre Maxted
Iteration for E changed to that given by Reidel , Feb 95,Pierre Maxted
/SINGLE keyword removed. May 96,Pierre Maxted
;
Removed limitation of time system on HJD, C. Markwardt, 2011-04-15
Change convergence test from relative to absolute precision on E
Pierre Maxted, Apr 12
(See astrolib/pro/helio_rv.pro)
HERMITE
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NAME:
HERMITE
PURPOSE:
To compute Hermite spline interpolation of a tabulated function.
EXPLANATION:
Hermite interpolation computes the cubic polynomial that agrees with
the tabulated function and its derivative at the two nearest
tabulated points. It may be preferable to Lagrangian interpolation
(QUADTERP) when either (1) the first derivatives are known, or (2)
one desires continuity of the first derivative of the interpolated
values. HERMITE() will numerically compute the necessary
derivatives, if they are not supplied.
CALLING SEQUENCE:
F = HERMITE( XX, FF, X, [ FDERIV = ])
INPUT PARAMETERS:
XX - Vector giving tabulated X values of function to be interpolated
Must be either monotonic increasing or decreasing
FF - Tabuluated values of function, same number of elements as X
X - Scalar or vector giving the X values at which to interpolate
OPTIONAL INPUT KEYWORD:
FDERIV - function derivative values computed at XX. If not supplied,
then HERMITE() will compute the derivatives numerically.
The FDERIV keyword is useful either when (1) the derivative
values are (somehow) known to better accuracy than can be
computed numerically, or (2) when HERMITE() is called repeatedly
with the same tabulated function, so that the derivatives
need be computed only once.
OUTPUT PARAMETER:
F - Interpolated values of function, same number of points as X
EXAMPLE:
Interpolate the function 1/x at x = 0.45 using tabulated values
with a spacing of 0.1
IDL> x = findgen(20)*0.1 + 0.1
IDL> y = 1/x
IDL> print,hermite(x,y,0.45)
This gives 2.2188 compared to the true value 1/0.45 = 2.2222
IDL> yprime = -1/x^2 ;But in this case we know the first derivatives
IDL> print,hermite(x,y,0.45,fderiv = yprime)
== 2.2219 ;and so can get a more accurate interpolation
NOTES:
The algorithm here is based on the FORTRAN code discussed by
Hill, G. 1982, Publ Dom. Astrophys. Obs., 16, 67. The original
FORTRAN source is U.S. Airforce. Surveys in Geophysics No 272.
HERMITE() will return an error if one tries to interpolate any values
outside of the range of the input table XX
PROCEDURES CALLED:
None
REVISION HISTORY:
Written, B. Dorman (GSFC) Oct 1993, revised April 1996
Added FDERIV keyword, W. Landsman (HSTX) April 1996
Test for out of range values W. Landsman (HSTX) May 1996
Converted to IDL V5.0 W. Landsman September 1997
Use VALUE_LOCATE instead of TABINV W. Landsman February 2001
(See astrolib/pro/hermite.pro)
HEULER
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NAME:
HEULER
PURPOSE:
Change the coordinate system of a FITS header or astrometry structure
EXPLANATION:
Converts a FITS header or a astrometry structure containing WCS (world
coordinate system) information between celestial, ecliptic, and
Galactic coordinates
CALLING SEQUENCE:
HEULER, hdr, [/GALACTIC, /CELESTIAL, /ECLIPTIC, ALT_IN = , ALT_OUT=]
or
HEULER, astr, /GALACTIC, /CELESTIAL, /ECLIPTIC
INPUT/OUTPUT PARAMETERS:
hdr - FITS header (string array) containing WCS information
or
Astr - Astrometry structure as extracted from a FITS header
by extast.pro (See EXTAST for more info).
Header or astrometry structure will be modified by the program to
contain astrometry in the new coordinates system.
REQUIRED INPUT KEYWORDS:
One of the following exclusive keywords is *required*
/GALACTIC - Convert the header to Galactic coordinates
/CELESTIAL - Convert the header to celestial (RA & Dec) coordinates
/ECLIPTIC - Convert the header to ecliptic coordinates
OPTIONAL INPUT KEYWORDS:
The following two keywords apply if the FITS header contains multiple
WCS keywords. See Section 3.3 of Greisen & Calabretta (2002, A&A, 395,
1061) for information about alternate astrometry keywords.
ALT_IN - single character 'A' through 'Z' or ' ' specifying an
alternate astrometry system present in the input FITS header. The
default isto use the primary astrometry or ALT = ' '. If /ALT_IN
is set, then this is equivalent to ALT_IN = 'A'.
ALT_OUT - single character specifying the alternate WCS keywords
to write the *output* astrometry. If not specified, then ALT_OUT
is set equal to ALT_IN.
RESTRICTIONS:
Currently assumes that celestial and ecliptic coordinates are in
J2000. Use HPRECESS if this is not the case.
ST Guide Star (DSS) image headers are first converted to a standard
tangent projection, prior to the coordinate conversion
METHOD:
The algorithm used is described in Section 2.7 of Calabretta & Greisen
(2002, A&A, 395, 1077). The CRVAL coordinates are transformed
directly using EULER. The new LONPOLE and LATPOLE values are then
determined by transforming the pole of the new system to the old, and
converted to native coordinates using WCS_ROTATE.
EXAMPLE:
A FITS header, hdr, has a standard tangent projection WCS information.
Add an alternate 'G' Galactic projection. Note that the original
WCS information will be left unchanged
IDL> heuler, hdr, /Galactic, alt='G'
PROCEDURES USED:
EULER, EXTAST, GSSS_STDAST, PUTAST, SXADDHIST, WCS_ROTATE
REVISION HISTORY:
Written W. Landsman June 2003
Use PV2 tag in astrometry structure rather than PROJP1 W. L. May 2004
Use double precision to compute new North pole W.L. Aug 2005
(See astrolib/pro/heuler.pro)
HEXTRACT
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NAME:
HEXTRACT
PURPOSE:
Extract a subimage from an array and update astrometry in FITS header
EXPLANATION:
Extract a subimage from an array and create a new FITS header with
updated astrometry for the subarray
CALLING SEQUENCE:
HEXTRACT, Oldim, Oldhd, [ Newim, Newhd, x0, x1, y0, y1, /SILENT ]
or
HEXTRACT, Oldim, Oldhd, [x0, x1, y0, y1, /SILENT, ERRMSG = ]
INPUTS:
Oldim - the original image array
Oldhd - the original image header
OPTIONAL INPUTS:
x0, x1, y0, y1 - respectively, first and last X pixel, and first and
last Y pixel to be extracted from the original image, integer scalars.
HEXTRACT will convert these values to long integers.
If omitted, HEXTRACT will prompt for these parameters
OPTIONAL OUTPUTS:
Newim - the new subarray extracted from the original image
Newhd - header for newim containing updated astrometry info
If output parameters are not supplied or set equal to
-1, then the HEXTRACT will modify the input parameters
OLDIM and OLDHD to contain the subarray and updated header.
OPTIONAL INPUT KEYWORD:
ALT - Single character 'A' through 'Z' or ' ' specifying which astrometry
system to modify in the FITS header. The default is to use the
primary astrometry or ALT = ' '. See Greisen and Calabretta (2002)
for information about alternate astrometry keywords.
/SILENT - If set and non-zero, then a message describing the extraction
is not printed at the terminal. This message can also be
suppressed by setting !QUIET.
OPTIONAL KEYWORD OUTPUT:
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
PROCEDURE:
The FITS header parameters NAXIS1, NAXIS2, CRPIX1, and CRPIX2 are
updated for the extracted image.
EXAMPLE:
Read an image from a FITS file 'IMAGE', extract a 512 x 512 subimage
with the same origin, and write to a new FITS file 'IMAGENEW'
IDL> im = READFITS( 'IMAGE', hdr ) ;Read FITS files into IDL arrays
IDL> hextract, im, h, 0, 511, 0, 511 ;Extract 512 x 512 subimage
IDL> writefits, 'IMAGENEW', im ,h ;Write subimage to a FITS file
PROCEDURES CALLED
CHECK_FITS, STRN(), SXPAR(), SXADDPAR, SXADDHIST
MODIFICATION HISTORY:
Written, Aug. 1986 W. Landsman, STX Corp.
Use astrometry structure, W. Landsman Jan, 1994
Minor fix if bad Y range supplied W. Landsman Feb, 1996
Added /SILENT keyword W. Landsman March, 1997
Added ERRMSG keyword W. Landsman May 2000
Work for dimensions larger than 32767 W.L., M.Symeonidis Mar 2007
Added ALT keyword W.L. April 2007
Use V6.0 notation W.L. October 2012
(See astrolib/pro/hextract.pro)
HGREP
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NAME:
HGREP
PURPOSE:
Find a substring in a FITS header (or any other string array)
CALLING SEQUENCE:
HGREP, header, substring, [/KEEPCASE, /LINENUM ]
INPUTS:
header - FITS header or other string array
substring - scalar string to find in header; if a numeric value is
supplied, it will be converted to type string
OPTIONAL INPUT KEYWORDS:
/KEEPCASE: if set, then look for an exact match of the input substring
Default is to ignore case .
/LINENUM: if set, prints line number of header in which
substring appears
OUTPUTS:
None, results are printed to screen
EXAMPLE:
Find every place in a FITS header that the word 'aperture'
appears in lower case letters and print the element number
of the header array:
IDL> hgrep, header, 'aperture', /keepcase, /linenum
HISTORY:
Written, Wayne Landsman (Raytheon ITSS) August 1998
Adapted from STIS version by Phil Plait/ ACC November 14, 1997
Remove trailing spaces if a non-string is supplied W. Landsman Jun 2002
(See astrolib/pro/hgrep.pro)
HISTOGAUSS
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NAME:
HISTOGAUSS
PURPOSE:
Histograms data and overlays it with a Gaussian. Draws the mean, sigma,
and number of points on the plot.
CALLING SEQUENCE:
HISTOGAUSS, Sample, A, [XX, YY, GX, GY, /NOPLOT, /NOFIT, FONT=,
CHARSIZE = ]
INPUT:
SAMPLE = Vector to be histogrammed
OUTPUT ARGUMENTS:
A = coefficients of the Gaussian fit: Height, mean, sigma
A[0]= the height of the Gaussian
A[1]= the mean
A[2]= the standard deviation
A[3]= the half-width of the 95% conf. interval of the standard
mean
A[4]= 1/(N-1)*total( (y-mean)/sigma)^2 ) = a measure of
normality
Below: superceded. The formula is not entirely reliable.
A[4]= measure of the normality of the distribution. =1.0, perfectly
normal. If no more than a few hundred points are input, there are
formulae for the 90 and 95% confidence intervals of this quantity:
M=ALOG10(N-1) ; N = number of points
T90=ABS(.6376-1.1535*M+.1266*M^2) ; = 90% confidence interval
IF N LT 50 THEN T95=ABS(-1.9065-2.5465*M+.5652*M^2) $
ELSE T95=ABS( 0.7824-1.1021*M+.1021*M^2) ;95% conf.
(From Martinez, J. and Iglewicz, I., 1981, Biometrika, 68, 331-333.)
XX = the X coordinates of the histogram bins (CENTER)
YY = the Y coordinates of the histogram bins
GX = the X coordinates of the Gaussian fit
GY = the Y coordinates of the Gaussian fit
OPTIONAL INPUT KEYWORDS:
/NOPLOT - If set, nothing is drawn
/FITIT If set, a Gaussian is actually fitted to the distribution.
By default, a Gaussian with the same mean and sigma is drawn;
the height is the only free parameter.
CHARSIZE Size of the characters in the annotation. Default = 0.82.
FONT - scalar font graphics keyword (-1,0 or 1) for text
/WINDOW - set to plot to a resizeable graphics window
_EXTRA - Any value keywords to the cgPLOT command (e.g. XTITLE) may also
be passed to HISTOGAUSS
SUBROUTINE CALLS:
BIWEIGHT_MEAN, which determines the mean and std. dev.
AUTOHIST, which draws the histogram
GAUSSFIT() (IDL Library) which does just that
REVISION HISTORY:
Written, H. Freudenreich, STX, 12/89
More quantities returned in A, 2/94, HF
Added NOPLOT keyword and print if Gaussian, 3/94
Stopped printing confidence limits on normality 3/31/94 HF
Added CHARSIZE keyword, changed annotation format, 8/94 HF
Simplified calculation of Gaussian height, 5/95 HF
Convert to V5.0, use T_CVF instead of STUDENT_T, GAUSSFIT instead of
FITAGAUSS W. Landsman April 2002
Correct call to T_CVF for calculation of A[3], 95% confidence interval
P. Broos/W. Landsman July 2003
Allow FONT keyword to be passed. T. Robishaw Apr. 2006
Use Coyote Graphics for plotting W.L. Mar 2011
Better formatting of text output W.L. May 2012
(See astrolib/pro/histogauss.pro)
HOR2EQ
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NAME:
HOR2EQ
PURPOSE:
Converts local horizon coords (alt-az) of something to equatorial (ra-dec).
EXPLANATION:
This is a nice code to calculate equatorial (ra,dec) coordinates from
horizon (alt,az) coords. It is typically accurate to about 1 arcsecond
or better (I have checked the output against the publicly available XEPHEM
software). It performs precession, nutation, aberration, and refraction
corrections. The perhaps best thing about it is that it can take arrays
as inputs, in all variables and keywords EXCEPT Lat, lon, and Altitude
(the code assumes these aren't changing), and uses vector arithmetic in
every calculation except when calculating the precession matrices.
CALLING SEQUENCE:
HOR2EQ, alt, az, jd, ra, dec, [ha, LAT= , LON= , /WS, OBSNAME= , $
/B1950 , PRECESS_= 0, NUTATE_= 0, REFRACT_= 0, $
ABERRATION_= 0, ALTITUDE= , /VERBOSE, _EXTRA= ]
INPUT VARIABLES
alt : altitude (in degrees) [scalar or vector]
az : azimuth angle (in degrees, measured EAST from NORTH, but see
keyword WS below.) [scalar or vector]
JD : Julian Date [scalar or vector], double precision
Note: if RA and DEC are arrays, then alt and az will also be arrays.
If RA and DEC are arrays, JD may be a scalar OR an array of
the same dimensionality.
OPTIONAL INPUT KEYWORDS:
lat : north geodetic latitude of location in degrees
lon : EAST longitude of location in degrees
(Specify west longitude with a negative sign.)
/WS : Set this to get the azimuth measured westward from south
(not East of North).
obsname : Set this to a valid observatory name to be used by the
astrolib OBSERVATORY procedure, which will return the latitude
and longitude to be used by this program.
/B1950 : Set this if your ra and dec are specified in B1950,
FK4 coordinates (instead of J2000, FK5)
precess_ : Set this to 1 to force precession [default], 0 for no
precession.
nutate_ : Set this to 1 to force nutation [default], 0 for no nutation.
aberration_ : Set this to 1 to force aberration correction [default],
0 for no correction.
refract_ : Set to 1 to force refraction correction [default], 0 for
no correction.
altitude: The altitude of the observing location, in meters. [default=0].
/verbose: Set this for verbose output. The default is verbose=0.
_extra: This is for setting TEMPERATURE or PRESSURE explicitly, which are
used by CO_REFRACT to calculate the refraction effect of the
atmosphere. If you don't set these, the program will make an
intelligent guess as to what they are (taking into account your
altitude). See CO_REFRACT for more details.
OUTPUT VARIABLES
ra : Right Ascension of object (J2000) in degrees (FK5); scalar or
vector.
dec : Declination of object (J2000) in degrees (FK5), scalar or vector.
ha : hour angle (in degrees) (optional)
DEPENDENCIES:
NUTATE, PRECESS, ADSTRING(), SUNPOS, OBSERVATORY (from the astrolib)
CO_NUTATE, CO_ABERRATION, CO_REFRACT, HADEC2ALTAZ
BASIC STEPS
Precess Ra-Dec to current equinox.
Nutation Correction to Ra-Dec
Aberration correction to Ra-Dec
Calculate Local Mean Sidereal Time
Calculate Local Apparent Sidereal Time
Calculate Hour Angle
Do Spherical Trig to find Apparent Alt-Az
Apply refraction correction to find observed Alt.
CORRECTIONS I DO NOT MAKE:
* Deflection of Light by the sun due to GR. (typically milliarcseconds,
can be arcseconds within one degree of the sun)
* The Effect of Annual Parallax (typically < 1 arcsecond)
* and more (see below)
TO DO
* Better Refraction Correction. Need to put in wavelength dependence,
and integrate through the atmosphere.
* Topocentric Parallax Correction (will take into account elevation of
the observatory)
* Proper Motion (but this will require crazy lookup tables or something).
* Difference between UTC and UT1 in determining LAST -- is this important?
* Effect of Annual Parallax (is this the same as topocentric Parallax?)
* Polar Motion
* Better connection to Julian Date Calculator.
EXAMPLE:
You are at Kitt Peak National Observatory, looking at a star at azimuth
angle 264d 55m 06s and elevation 37d 54m 41s (in the visible). Today is
Dec 25, 2041 and the local time is 10 PM precisely. What is the ra and dec
(J2000) of the star you're looking at? The temperature here is about 0
Celsius, and the pressure is 781 millibars. The Julian date for this
time is 2466879.7083333
IDL> hor2eq, ten(37,54,41), ten(264,55,06), 2466879.7083333d, ra, dec, $
/verb, obs='kpno', pres=781.0, temp=273.0
The program produces this output (because the VERBOSE keyword was set):
Latitude = +31 57 48.0 Longitude = *** 36 0.0 ; longitude prints weirdly b/c of negative input to ADSTRING!!
Julian Date = 2466879.708333
Az, El = 17 39 40.4 +37 54 41.0 (Observer Coords)
Az, El = 17 39 40.4 +37 53 39.6 (Apparent Coords)
LMST = +03 53 54.1
LAST = +03 53 53.6
Hour Angle = +03 38 30.1 (hh:mm:ss)
Ra, Dec: 00 15 23.5 +15 25 1.9 (Apparent Coords)
Ra, Dec: 00 15 24.2 +15 25 0.1 (J2041.9841)
Ra, Dec: 00 13 14.1 +15 11 0.3 (J2000)
The star is therefore Algenib! Compare the derived Ra, Dec with what XEPHEM
got:
Ra, Dec: 00 13 14.2 +15 11 1.0 (J2000)
AUTHOR:
Chris O'Dell
Univ. of Wisconsin-Madison
Observational Cosmology Laboratory
Email: [email protected]
REVISION HISTORY:
Made all integers type LONG W. Landsman September 2007
Fixed for case of scalar Julian date but vector positions W L June 2009
(See astrolib/pro/hor2eq.pro)
HOST_TO_IEEE
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NAME:
HOST_TO_IEEE
PURPOSE:
Translate an IDL variable from host to IEEE representation
EXPLANATION:
The variable is converted from the format used by the host architecture
into IEEE-754 representation ("big endian" as used, e.g., in FITS data ).
Duplicates most of the functionality of the SWAP_ENDIAN_INPLACE procedure
with the addition of the IDLTYPE keyword.
CALLING SEQUENCE:
HOST_TO_IEEE, data, [ IDLTYPE = ]
INPUT-OUTPUT PARAMETERS:
data - any IDL variable, scalar or vector. It will be modified by
HOST_TO_IEEE to convert from host to IEEE representation. Byte
and string variables are returned by HOST_TO_IEEE unchanged
OPTIONAL KEYWORD INPUTS:
IDLTYPE - scalar integer (1-15) specifying the IDL datatype according
to the code given by the SIZE function. This keyword
will usually be used when supplying a byte array that needs
to be interpreted as another data type (e.g. FLOAT).
EXAMPLE:
Suppose FITARR is a 2880 element byte array to be converted to a FITS
record and interpreted a FLOAT data.
IDL> host_to_ieee, FITARR, IDLTYPE = 4
METHOD:
The BYTEORDER procedure is called with the appropriate keywords
MODIFICATION HISTORY:
Adapted from CONV_UNIX_VAX, W. Landsman Hughes/STX January, 1992
Version for IDL V5.0 August 1997
Converted to IDL V5.0 W. Landsman September 1997
Added new integer datatypes C. Markwardt/W. Landsman July 2000
Use /SWAP_IF_LITTLE_ENDIAN keyword for 64bit types W. Landsman Feb 2003
Do not use XDR keywords to BYTEORDER for much improved speed
W. Landsman April 2006
(See astrolib/pro/host_to_ieee.pro)
HPRECESS
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NAME:
HPRECESS
PURPOSE:
Precess the astrometry in a FITS header to a new equinox
CALLING SEQUENCE:
HPRECESS, HDR, [ yearf ]
INPUT-OUTPUT:
HDR - FITS Header, must contain the CRVAL astrometry keywords,
and either an EPOCH or EQUINOX keyword.
HDR will be modified to contain the precessed astrometry
OPTIONAL INPUT:
YEARF - Scalar, giving the year of the new (Final) equinox.
If not supplied, user will be prompted for this value.
METHOD:
The CRVAL and CD (or CROTA) keywords are extracted from the header
and precessed to the new equinox. The EPOCH or EQUINOX keyword in
the header is updated. A HISTORY record is added
RESTRICTIONS:
The FK5 reference frame is assumed for both equinoxes.
PROCEDURES USED:
EXTAST, GET_EQUINOX(), SXADDPAR, SXADDHIST, PRECESS, PRECESS_CD
PUTAST, ZPARCHECK
REVISION HISTORY:
Written W. Landsman STX July, 1988
CD matrix precessed - February, 1989
Update EQUINOX keyword when CROTA2 present November, 1992
Recognize a GSSS header June, 1994
Additional Noparams value recognize for storing CDs. RSH, 6 Apr 95
Understand reversed X,Y (X-Dec, Y-RA) axes, W. Landsman October 1998
Correct algorithm when CROTA2 is in header W. Landsman April 2006
Correct sign error introduced April 2006, include CDELT values
when computing rotation of pole W. Landsman July 2007
Call hprecess/jprecess for 1950<>2000 W. L. Aug 2009
(See astrolib/pro/hprecess.pro)
HPRINT
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NAME:
HPRINT
PURPOSE:
Display a FITS header (or other string array)
EXPLANATION:
On a GUI terminal, the string array is displayed using XDISPSTR.
If printing at a non-GUI terminal, the string array is printed 1 line
at a time, to make sure that each element of the string array is
displayed on a separate line.
CALLING SEQUENCE:
HPRINT, h, [ firstline ]
INPUTS:
H - FITS header (or any other string array).
OPTIONAL INPUT:
FIRSTLINE - scalar integer specifying the first line to begin
displaying. The default is FIRSTLINE = 1, i.e. display
all the lines. If Firstline is negative, then the first
line to be printed is counted backward from the last line.
NOTES:
When displaying at the terminal, HPRINT has the following differences
from the intrinsic PRINT procedure
(1) Arrays are printed one line at a time to avoid a space between 80
character lines
(2) Lines are trimmed with STRTRIM before being printed to speed up
display
(3) The /more option is used for output.
EXAMPLE:
Read the header from a FITS file named 'test.fits' and display it at the
terminal beginning with line 50
IDL> h = headfits( 'test.fits') ;Read FITS header
IDL> hprint, h, 50 ;Display starting at line 50
To print the last 25 lines of the header
IDL> hprint, h, -25
REVISION HISTORY:
Written W. Landsman July, 1990
Added test for user quit July, 1991
Added optional FIRSTLINE parameter November, 1992
Modified for when STDOUT is not a TTY W. Landsman September 1995
Converted to IDL V5.0 W. Landsman September 1997
Fixed printing in IDLDE, C. Gehman August, 1998
Skip PRINTF if IDL in demo mode W. Landsman October 2004
Fixed bug on non-terminals, William Thompson, 18-Oct-2004
Assume since V5.4 Use BREAK instead of GOTO W. Landsman Apr 2006
Call XDISPSTR on a GUI terminal W. Landsman Jun 2006
(See astrolib/pro/hprint.pro)
HREBIN
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NAME:
HREBIN
PURPOSE:
Expand or contract a FITS image using (F)REBIN and update the header
EXPLANATION:
If the output size is an exact multiple of the input size then REBIN is
used, else FREBIN is used. User can either overwrite the input array,
or write to new variables.
CALLING SEQUENCE:
HREBIN, oldhd ;Special calling sequence to just update header
HREBIN, oldim, oldhd, [ newim, newhd, newx, newy, OUTSIZE = ,/SAMPLE,
ERRMSG = ]
INPUTS:
OLDIM - the original image array
OLDHD - the original image FITS header, string array
OPTIONAL INPUTS:
NEWX - size of the new image in the X direction, integer scalar
NEWY - size of the new image in the Y direction, integer scalar
HREBIN will prompt for NEWX and NEWY if not supplied
OPTIONAL OUTPUTS:
NEWIM - the image after expansion or contraction with REBIN
NEWHD - header for newim containing updated astrometry info
If output parameters are not supplied, the program will modify
the input parameters OLDIM and OLDHD to contain the new array and
updated header.
OPTIONAL INPUT KEYWORDS:
/SAMPLE - Expansion or contraction is done using REBIN which uses
bilinear interpolation when magnifying and boxaveraging when
minifying. If the SAMPLE keyword is supplied and non-zero,
then nearest neighbor sampling is used in both cases. Keyword
has no effect when output size is not a multiple of input size.
OUTSIZE - Two element integer vector which can be used instead of the
NEWX and NEWY parameters to specify the output image dimensions
ALT - Single character 'A' through 'Z' or ' ' specifying which astrometry
system to modify in the FITS header. The default is to use the
primary astrometry of ALT = ' '. See Greisen and Calabretta (2002)
for information about alternate astrometry keywords.
OPTIONAL KEYWORD OUTPUT:
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
PROCEDURE:
The parameters BSCALE, NAXIS1, NAXIS2, CRPIX1, and CRPIX2 and the CD
(or CDELT) parameters are updated for the new FITS header.
EXAMPLE:
Compress a 2048 x 2048 image array IM, with FITS header HDR, to a
724 x 724 array. Overwrite the input variables with the compressed
image and header.
IDL> hrebin, im, hdr, OUT = [724, 724]
PROCEDURES USED:
CHECK_FITS, EXTAST, FREBIN, GSSS_STDAST, STRN(), SXPAR(), SXADDHIST,
SXADDPAR, ZPARCHECK
MODIFICATION HISTORY:
Written, December 1990 W. Landsman, ST System Corp.
Update CD1_1 keywords W. Landsman November 1992
Check for a GSSS header W. Landsman June 1994
Update BSCALE even if no astrometry present W. Landsman May 1997
Converted to IDL V5.0 W. Landsman September 1997
Use FREBIN to accept sizes that are not a integer multiple of the original
size W. Landsman August 1998
Correct for "edge" effects when expanding with REBIN W. Landsman Apr. 1999
Fixed initialization of header only call broken in Apr 98 change May. 1999
Remove reference to obsolete !ERR W. Landsman February 2000
Use double precision formatting for CD matrix W. Landsman April 2000
Recognize PC00n00m astrometry format W. Landsman December 2001
Correct astrometry for integral contraction W. Landsman April 2002
Fix output astrometry for non-equal plate scales for PC matrix or
CROTA2 keyword, added ALT keyword. W. Landsman May 2005
Update distortion parameters if present W. Landsman August 2007
Don't update BSCALE/BZERO for unsigned integer W.Landsman Mar 2008
Use post-V6.0 notation W. Landsman Nov 2011
Write CRPIX values as double precision if necessay W. Landsman Oct. 2012
(See astrolib/pro/hrebin.pro)
HREVERSE
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NAME:
HREVERSE
PURPOSE:
Reverse an image about either dimension and update FITS astrometry
EXPLANATION:
Reverse an image about either the X or Y axis, and create a new
header with updated astrometry for the reversed image.
CALLING SEQUENCE:
HREVERSE,oldim,oldhd, [ subs, /SILENT ] ;Update input image and header
or
HREVERSE, oldim, oldhd, newim, newhd, [ subs, /SILENT ]
INPUTS:
OLDIM - the original image array
OLDHD - the original image header
OPTIONAL INPUTS:
SUBS - Subs equals 1 to reverse the order of the X dimension,
2 to reverse Y order. If omitted, then HREVERSE will
prompt for this scalar parameter.
OPTIONAL OUTPUTS:
NEWIM - the rotated image, with the same dimensions as Oldim
NEWHD - header for newim containing updated astrometry info
If output parameters are not supplied, the program
will modify the input parameters OLDIM and OLDHD
to contain the rotated image and updated header.
OPTIONAL KEYWORD INPUT:
SILENT - if set and non-zero, then informative messages are suppressed.
OPTIONAL KEYWORD OUTPUT:
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
SIDE EFFECTS:
A right-handed coordinate system is converted into a left-
handed one, and vice-versa.
PROCEDURE:
The User's Library procedure REVERSE is used to reverse the image.
The CD and CRPIX header parameters are updated for the new header.
For AIPS type astrometry, the CDELT parameters are also updated.
A history record is also added to the header
PROCEDURES USED:
CHECK_FITS, EXTAST, REVERSE(), STRN(), SXADDPAR
MODIFICATION HISTORY:
Written, Aug. 1986 W. Landsman, STI Corp.
Error modifying CROTA angles corrected 9-23-88
Added format keyword, J. Isensee, July, 1990
Work for ST Guide Star images, W. Landsman HSTX, May 1995
Compute CRPIX1 correctly for X reversal W. Landsman HSTX August 1995
Converted to IDL V5.0 W. Landsman September 1997
Added ERRMSG, Use double precision formatting, W. Landsman April 2000
Recognize PC00n00m astrometry matrix W. Landsman December 2001
Use V6.0 notation W. Landsman October 2012
(See astrolib/pro/hreverse.pro)
HROT
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NAME:
HROT
PURPOSE:
Rotate an image and create new FITS header with updated astrometry.
EXPLANATION:
Cubic, bilinear or nearest neighbor interpolation can be used.
CALLING SEQUENCE:
HROT, oldim, oldhd, [ newim, newhd, angle, xc, yc, int,
MISSING =, INTERP =, CUBIC = , /PIVOT]
INPUTS:
OLDIM - the original image array
OLDHD - the original FITS image header, string array
OPTIONAL INPUTS:
NEWIM - If NEWIM is set to -1, then the old image and header will
be updated
ANGLE - Rotation angle, degrees clockwise, scalar
XC - X Center of rotation (-1 for center of image)
YC - Y Center of rotation (-1 for center of image)
INT - 0 for nearest neighbor, 1 for bilinear interpolation
2 for cubic interpolation.
OPTIONAL OUTPUTS:
NEWIM - the rotated image, with the same dimensions as Oldim
NEWHD - header for newim containing updated astrometry info
If output parameters are not supplied, the program
will modify the input parameters OLDIM and OLDHD
to contain the rotated image and updated header.
OPTIONAL INPUT KEYWORD:
MISSING - Set this keyword to a scalar value which will be assigned
to pixels in the output image which do not correspond to
existing input images (e.g if one rotates off-center).
If not supplied then linear extrapolation is used.
***NOTE: A bug was introduced into the POLY_2D function in IDL
V5.5 (fixed in V6.1) such that the MISSING keyword
may not work properly with floating point data***
INTERP - scalar set to either 0 (nearest neighbor interpolation),
1 (bilinear interpolation), or 2 (cubic interpolation).
The interpolation type can be specified by either the INTERP
keyword or the int parameter
CUBIC - If set and non-zero then cubic interpolation is used (see ROT),
which is equivalent to setting INT = 2. In IDL V5.0 and later,
this keyword can also be set to a value between -1 and 0.
/PIVOT - Setting this keyword causes the image to pivot around the point
XC, YC, so that this point maps into the same point in the
output image. If this keyword is set to 0 or omitted, then the
point XC, YC in the input image is mapped into the center of
the output image.
OPTIONAL OUTPUT KEYWORD:
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
EXAMPLE:
Rotate an image non-interactively 30 degrees clockwise. Use
bilinear interpolation, and set missing values to 0.
IDL> HROT, im_old, h_old, im_new, h_new, 30, -1, -1, 1, MIS = 0
As above but update the input image and header and pivot about (100,120)
IDL> HROT, im_old, h_old, -1, -1, 30, 100, 120, 1, MIS = 0, /PIVOT
RESTRICTIONS:
Unlike the ROT procedure, HROT cannot be used to magnify or
or demagnify an image. Use HCONGRID or HREBIN instead.
PROCEDURE:
The image array is rotated using the ROT procedure.
The CD (or CROTA) and CRPIX parameters, if present in the FITS header,
are updated for the new rotation.
History records are also added to the header
PROCEDURES USED:
CHECK_FITS, EXTAST, GETOPT(), GETROT, ROT(), STRN(), SXADDPAR
MODIFICATION HISTORY:
Written, Aug. 1986 W. Landsman, ST Systems Corp.
Added MISSING keyword, W. Landsman March, 1991
Added cubic interpolation, use astrometry structure Feb 1994
Removed call to SINCE_VERSION() W. Landsman March 1996
Assume at least V3.5, add CUBIC parameter W. Landsman March 1997
Converted to IDL V5.0 W. Landsman September 1997
Fix for CROTA2 defined and CDELT1 NE CDELT2, W. Landsman November 1998
Fix documentation to specify clockwise rotation W. Landsman Dec. 1999
Added /PIVOT keyword W. Landsman January 2000
Added ERRMSG, Use double precision formatting, W. Landsman April 2000
Consistent conversion between CROTA and CD matrix W. Landsman Oct 2000
Work for both CD001001 and CDELT defined W. Landsman March 2001
Recognize PC matrix astrometry W. Landsman December 2001
Update astrometry correctly when /PIVOT applied W. Landsman March 2002
Update CROTA2 astrometry correctly, approximate GSSS W.L. June 2003
Work with CD1_1, PC1_1 and CROTA keywords W. L. July 2003
Work with angle as a 1 element vector W.L. May 2006
(See astrolib/pro/hrot.pro)
HROTATE
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NAME:
HROTATE
PURPOSE:
Apply the IDL ROTATE function and update astrometry in a FITS header
EXPLANATION:
Apply the intrinsic IDL ROTATE function to an image and update
astrometry in the associated FITS header.
CALLING SEQUENCE:
HROTATE, oldim, oldhd, newim, newhd, direction
or
HROTATE, oldim, oldhd, direction
INPUTS:
OLDIM - the original image array
OLDHD - the original FITS image header, string array
DIRECTION - Scalar integer (0-7) specifying rotation direction,
exactly as specified by the IDL ROTATE function.
Direction Transpose? Rot. CCW X1 Y1
----------------------------------------
0 No None X0 Y0 (no change)
1 No 90 -Y0 X0
2 No 180 -X0 -Y0
3 No 270 Y0 -X0
4 Yes None Y0 X0
5 Yes 90 -X0 Y0
6 Yes 180 -Y0 -X0
7 Yes 270 X0 -Y0
OPTIONAL OUTPUTS:
NEWIM - the rotated image, with the same dimensions as Oldim
NEWHD - header for newim containing updated astrometry info
If output parameters are not supplied, the program
will modify the input parameters OLDIM and OLDHD
to contain the rotated image and updated header.
OPTIONAL KEYWORD OUTPUT:
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
EXAMPLE:
Rotate an image exactly 90 degrees counterclockwise and update the
FITS image array and header.
IDL> HROT, im, h, im_new, h_new, 1
PROCEDURE:
The image array is rotated using the ROTATE function.
The CD (or CROTA) and CRPIX parameters, if present in the FITS header,
are updated for the new rotation.
History records are also added to the header
RESTRICTIONS:
Does not work Guide Star Survey (GSS) astrometry. Use GSSS_STDAST to
first convert
PROCEDURES USED:
CHECK_FITS(), SXADDPAR, EXTAST
MODIFICATION HISTORY:
Written, Mar 1997 W. Landsman, Hughes STX
Work for non-square images W. Landsman June 1998 Raytheon STX
Fix for different plate scales, and CROTA2 defined, November 1998
Added ERRMSG, Use double precision formatting, W. Landsman April 2000
Consistent conversion between CROTA and CD matrix W. Landsman Oct 2000
Correct update when CROTA keyword present W. Landsman June 2003
Update CDELT for AIPS-style astrometry headers M. Perrin/WL Jul 2003
Convert GSS astrometry to WCS W. Landsman November 2004
Work even if no astrometry present, just update NAXIS* WL June 2011
(See astrolib/pro/hrotate.pro)
IEEE_TO_HOST
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NAME:
IEEE_TO_HOST
PURPOSE:
Translate an IDL variable from IEEE-754 to host representation
EXPLANATION:
The variable is translated from IEEE-754 ("big-endian" as used, for
example, in FITS data ), into the host machine architecture.
Duplicates most of the functionality of the SWAP_ENDIAN_INPLACE procedure
introduced in V5.6, with the addition of the IDLTYPE keyword.
CALLING SEQUENCE:
IEEE_TO_HOST, data, [ IDLTYPE = , ]
INPUT-OUTPUT PARAMETERS:
data - any IDL variable, scalar or vector. It will be modified by
IEEE_TO_HOST to convert from IEEE to host representation. Byte
and string variables are returned by IEEE_TO_HOST unchanged
OPTIONAL KEYWORD INPUTS:
IDLTYPE - scalar integer (1-15) specifying the IDL datatype according
to the code given by the SIZE function. This keyword
is usually when DATA is a byte array to be interpreted as
another datatype (e.g. FLOAT).
EXAMPLE:
A 2880 byte array (named FITARR) from a FITS record is to be
interpreted as floating and converted to the host representaton:
IDL> IEEE_TO_HOST, fitarr, IDLTYPE = 4
METHOD:
The BYTEORDER procedure is called with the appropriate keyword
MODIFICATION HISTORY:
Written, W. Landsman Hughes/STX May, 1992
Converted to IDL V5.0 W. Landsman September 1997
Under VMS check for IEEE -0.0 values January 1998
VMS now handle -0.0 values under IDL V5.1 July 1998
Added new integer datatypes C. Markwardt/W. Landsman July 2000
Post-V5.1 version, no VMS negative zero check W. Landsman July 2001
Use size(/type) W. Landsman December 2002
Use /SWAP_IF_LITTLE_ENDIAN keyword for 64bit types W. Landsman Feb 2003
Do not use XDR keywords to BYTEORDER for much improved speed
W. Landsman April 2006
Update cosmetic typo for structures W. Landsman October 2006
(See astrolib/pro/ieee_to_host.pro)
IMCONTOUR
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NAME:
IMCONTOUR
PURPOSE:
Make a contour plot labeled with astronomical coordinates.
EXPLANATION:
The type of coordinate display is controlled by the keyword TYPE
Set TYPE=0 (default) to measure distances from the center of the image
(IMCONTOUR will decide whether the plotting units will be in
arc seconds, arc minutes, or degrees depending on image size.)
Set /TYPE for standard RA and Dec labeling
By using the /NODATA keyword, IMCONTOUR can also be used to simply
provide astronomical labeling of a previously displayed image.
CALLING SEQUENCE
IMCONTOUR, im, hdr,[ /TYPE, /PUTINFO, XDELTA = , YDELTA =, _EXTRA =
XMID=, YMID= ]
INPUTS:
IM - 2-dimensional image array
HDR - FITS header associated with IM, string array, must include
astrometry keywords. IMCONTOUR will also look for the
OBJECT and IMAGE keywords, and print these if found and the
PUTINFO keyword is set.
OPTIONAL PLOTTING KEYWORDS:
/TYPE - the type of astronomical labeling to be displayed. Either set
TYPE = 0 (default), distance to center of the image is
marked in units of Arc seconds, arc minutes, or degrees
TYPE = 1 astronomical labeling with Right ascension and
declination.
/PUTINFO - If set, then IMCONTOUR will add information about the image
to the right of the contour plot. Information includes image
name, object, image center, image center, contour levels, and
date plot was made
XDELTA, YDELTA - Integer scalars giving spacing of labels for TYPE=1.
Default is to label every major tick (XDELTA=1) but if
crowding occurs, then the user might wish to label every other
tick (XDELTA=2) or every third tick (XDELTA=3)
XMID, YMID - Scalars giving the X,Y position from which offset distances
will be measured when TYPE=0. By default, offset distances
are measured from the center of the image.
/OVERLAY - If set, then IMCONTOUR is assumed to overlay an image.
This requires 1 extra pixel be included on the X and Y axis,
to account for edge effects in the image display. Setting
OVERLAY provide a better match of the contour and underlying
image but is not as aesthetically pleasing because the contours
will not extend to the axes.
Any keyword accepted by CONTOUR may also be passed through IMCONTOUR
since IMCONTOUR uses the _EXTRA facility. IMCONTOUR uses its own
defaults for the XTITLE, YTITLE XMINOR, YMINOR, and SUBTITLE keywords
but these may be overridden. Note in particular the /NODATA keyword
which can be used if imcontour.pro is to only provide labeling.
NOTES:
(1) The contour plot will have the same dimensional ratio as the input
image array
(2) To contour a subimage, use HEXTRACT before calling IMCONTOUR
(3) Use the /NODATA keyword to simply provide astronomical labeling
of a previously displayed image.
(4) The IMCONTOUR display currently does not indicate the image
rotation in any way, but only specifies coordinates along the
edges of the image
EXAMPLE:
Overlay the contour of an image, im2, with FITS header, h2, on top
of the display of a different image, im1. Use RA, Dec labeling, and
seven equally spaced contour levels. The use of a program like
David Fanning's cgImage http://www.idlcoyote.com/programs/cgimage.pro
is suggested to properly overlay plotting and image coordinates. The
/Keep_aspect_ratio keyword must be used.
IDL> cgimage,im1,/keep_aspect, position = pos
IDL> imcontour,im2,h2,nlevels=7,/Noerase,/TYPE,position = pos
PROCEDURES USED:
CHECK_FITS, EXTAST, GETROT, TICPOS, TICLABEL, TIC_ONE, TICS, XYAD
CONS_RA(), CONS_DEC(), ADSTRING()
REVISION HISTORY:
Written W. Landsman STX May, 1989
Fixed RA,Dec labeling W. Landsman November, 1991
Fix plotting keywords W.Landsman July, 1992
Recognize GSSS headers W. Landsman July, 1994
Removed Channel keyword for V4.0 compatibility June, 1995
Add _EXTRA CONTOUR plotting keywords W. Landsman August, 1995
Add XDELTA, YDELTA keywords W. Landsman November, 1995
Use SYSTIME() instead of !STIME August, 1997
Remove obsolete !ERR system variable W. Landsman May 2000
Added XMID, YMID keywords to specify central position (default is still
center of image) W. Landsman March 2002
Recognize Galactic coordinates, fix Levels display when /PUTINFO set
W. Landsman May 2003
Correct conversion from seconds of RA to arcmin is 4 not 15.
M. Perrin July 2003
Fix integer truncation which appears with tiny images WL July 2004
Changed some keyword_set() to N_elements WL Sep 2006
Work to 1 pixels level when overlaying an image,added /OVERLAY keyword
Use FORMAT_AXIS_VALUES() W. Landsman Jan 2008
Make /OVERLAY always optional W. Landsman Feb 2008
Check if RA crosses 0 hours WL Aug 2008
Use Coyote Graphics WL Feb 2011
(See astrolib/pro/imcontour.pro)
IMDBASE
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NAME:
IMDBASE
PURPOSE:
Find the sources in an IDL database that are located on a given image.
CALLING SEQUENCE:
imdbase, hdr, [catalogue, list, ALT=, XPOS= ,YPOS=, XRANGE= ,YRANGE= ,
SUBLIST =, /SILENT ]
INPUTS:
hdr - FITS image header containing astrometry, and the NAXIS1,
NAXIS2 keywords giving the image size
catalogue - string giving name of catalogue in database. If not supplied
then the currently open database is used. The database must
contain the (preferably indexed) fields RA (in hours) and DEC.
Type DBHELP for a list of the names of available catalogues.
OPTIONAL OUTPUT PARAMETER:
LIST - A longwprd vector containing the entry numbers of sources found
within the image. This vector can then be used with other
database procedures, e.g. to print specified fields (DBPRINT)
or subselect with further criteria (DBFIND)
OPTIONAL OUTPUT KEYWORD PARAMETER:
XPOS - REAL*4 vector giving X positions of catalogue sources found
within the image
YPOS - REAL*4 vector giving Y positions of catalogue sources found
within the image
OPTIONAL INPUT KEYWORD PARAMETERS
ALT - single character 'A' through 'Z' or ' ' specifying an alternate
astrometry system present in the FITS header. The default is
to use the primary astrometry or ALT = ' '. If /ALT is set,
then this is equivalent to ALT = 'A'. See Section 3.3 of
Greisen & Calabretta (2002, A&A, 395, 1061) for information about
alternate astrometry keywords.
SILENT - If set, then informational messages are suppressed
SUBLIST - vector giving entries in the database to consider in the
search. If not supplied, or set equal to -1, then all entries
are considered.
XRANGE - 2 element vector giving the X range of the image to consider.
The default is to search for catalogue sources within the entire
image
YRANGE - 2 element vector giving the Y range of the image to consider.
NOTES:
If an output list vector is not supplied, then the found objects are
diplayed at the terminal.
EXAMPLE:
Find all existing IUE observations within the field of the FITS
file fuv0435fc.fits. Subselect those taken with the SWP camera
H = HEADFITS('fuv0435f.fits') ;Read FITS header
IMDBASE,H,'IUE',list ;Find IUE obs. within image
list2 = DBFIND('CAM_NO=3',list) ;Subselect on SWP images
SIDE EFFECTS:
The IDL database is left open upon exiting IMDBASE.
NOTES:
IMDBASE checks the description of the RA item in the database for the
string '1950'. If found, the database RA and Dec are assumed to be
in equinox B1950. Otherwise they are assumed to be in ICRS or J2000.
SYSTEM VARIABLES:
The non-standard system variable !TEXTOUT is required for use with the
database procedures.
PROCEDURES USED:
AD2XY, DBEXT, DB_ITEM, DB_ITEM_INFO(), DBOPEN, DBFIND(), EXTAST,
GET_EQUINOX(), GSSSADXY, GSSSXYAD, HPRECESS, SXPAR(), XY2AD
REVISION HISTORY:
Written W. Landsman September, 1988
Added SUBLIST keyword September, 1991
Updated to use ASTROMETRY structures J.D. Offenberg, HSTX, Jan 1993
Conversion for precession fixed. R.Hill, HSTX, 22-Apr-93
Check RA description for equinox W. Landsman Aug 96
Call HPRECESS if header equinox does not match DB W. Landsman Oct. 1998
Assume Equinox J2000 if not explicitly B1950 W. Landsman Jan. 2005
Added ALT keyword W. Landsman April 2005
Use open database, if no catalogue name given W.L April 2008
Added /SILENT keyword W.L. Mar 2009
(See astrolib/pro/imdbase.pro)
IMF
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NAME:
IMF
PURPOSE:
Compute an N-component power-law logarithmic initial mass function
EXPLANTION:
The function is normalized so that the total mass distribution
equals one solar mass.
CALLING SEQUENCE:
psi = IMF( mass, expon, mass_range )
INPUTS:
mass - mass in units of solar masses (scalar or vector)
Converted to floating point if necessary
expon - power law exponent, usually negative, scalar or vector
The number of values in expon equals the number of different
power-law components in the IMF
A Saltpeter IMF has a scalar value of expon = -1.35
mass_range - vector containing the mass upper and lower limits of the
IMF and masses where the IMF exponent changes. The number
of values in mass_range should be one more than in expon.
The values in mass_range should be monotonically increasing.
OUTPUTS
psi - mass function, number of stars per unit logarithmic mass interval
evaluated for supplied masses
NOTES:
The mass spectrum f(m) giving the number of stars per unit mass
interval is related to psi(m) by m*f(m) = psi(m). The normalization
condition is that the integral of psi(m) between the upper and lower
mass limit is unity.
EXAMPLE:
(1) Print the number of stars per unit mass interval at 3 Msun
for a Salpeter (expon = -1.35) IMF, with a mass range from
0.1 MSun to 110 Msun.
IDL> print, imf(3, -1.35, [0.1, 110] ) / 3
(2) Lequex et al. (1981, A & A 103, 305) describes an IMF with an
exponent of -0.6 between 0.007 Msun and 1.8 Msun, and an
exponent of -1.7 between 1.8 Msun and 110 Msun. Plot
the mass spectrum f(m)
IDL> m = [0.01,0.1,indgen(110) + 1 ] ;Make a mass vector
IDL> expon = [-0.6, -1.7] ;Exponent Vector
IDL> mass_range = [ 0.007, 1.8, 110] ;Mass range
IDL> plot,/xlog,/ylog, m, imf(m, expon, mass_range ) / m
METHOD
IMF first calculates the constants to multiply the power-law
components such that the IMF is continuous at the intermediate masses,
and that the total mass integral is one solar mass. The IMF is then
calculated for the supplied masses. Also see Scalo (1986, Fund. of
Cosmic Physics, 11, 1)
PROCEDURES CALLED:
None
REVISION HISTORY:
Written W. Landsman August, 1989
Set masses LE mass_u rather than LT mass_u August, 1992
Major rewrite to accept arbitrary power-law components April 1993
Convert EXPON to float if necessary W. Landsman March 1996
Remove call to DATATYPE, V5.3 version W. Landsman August 2000
(See astrolib/pro/imf.pro)
IMLIST
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NAME:
IMLIST
PURPOSE:
Display pixel values on an image surrounding a specified X,Y center.
EXPLANATION:
IMLIST is similar to TVLIST but the center pixel is supplied directly by
the user, rather than being read off of the image display
CALLING SEQUENCE:
IMLIST, Image, Xc, Yc, [ TEXTOUT = , DX = , DY = ,WIDTH = ,DESCRIP = ]
INPUTS:
Image - Two-dimensional array containing the image
Xc - X pixel value at which to center the display, integer scalar
Yc - Y pixel value at which to center the display, integer scalar
OPTIONAL INPUTS KEYWORDS:
TEXTOUT - Scalar number (1-7) or string which determines output device.
(see TEXTOPEN) The following dev/file is opened for output.
textout=1 TERMINAL using /more option
textout=2 TERMINAL without /more option
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file
textout=7 same as 3 but text is appended to .prt
if file already exists
textout = filename (default extension of .prt)
DX -Integer scalar giving the number of pixels inthe X direction
to be displayed. If omitted then DX = 18 for byte images, and
DX = 14 for integer images. IMLIST will display REAL data
with more significant figures if more room is available to
print.
DY - Same as DX, but in Y direction. If omitted, then DY = DX
WIDTH - Integer scalar giving the character width of the output device.
Default is 80 characters.
DESCRIP = Scalar string which will be written as a description over
the output pixel values. If DESCRIP is not supplied, and the
output device specified by TEXTOUT is not a terminal, then the
user will be prompted for a description.
OFFSET - 2 element numeric vector giving an offset to apply to the
display of the X,Y coordinates of the image (e.g. if the
supplied image array is a subarray of a larger image).
OUTPUTS:
None.
PROCEDURE:
Corresponding region of image is then displayed at
the terminal. If necessary, IMLIST will divide all pixel values
in a REAL*4 image by a (displayed) factor of 10 to make a pretty format.
SYSTEM VARIABLES:
If the keyword TEXTOUT is not supplied, then the non-standard system
variable !TEXTOUT will be read. (The procedure ASTROLIB can be
used to add the non-standard system variables.)
RESTRICTIONS:
IMLIST may not be able to correctly format all pixel values if the
dynamic range of the values near the center pixel is very large
EXAMPLE:
Display the pixel values of an image array IM in the vicinity of 254,111
IDL> imlist, IM, 254, 111
PROCEDURES USED
TEXTOPEN, F_FORMAT(), TEXTCLOSE
REVISION HISTORY:
Written, W. Landsman June, 1991
Added DESCRIP keyword W. Landsman December, 1991
Treat LONG image as integer when possible, call TEXTOPEN with /STDOUT
keyword, W. Landsman April, 1996
Use SYSTIME() instead of !STIME August 1997
Converted to IDL V5.0 W. Landsman September 1997
Recognize new integer types, added OFFSET keyword W. Landsman Jan. 2000
Replace DATATYPE() with size(/TNAME) W. Landsman Nov. 2001
Handle NAN values in output display W. Landsman June 2004
Use V6.0 notation W. Landsman April 2011
(See astrolib/pro/imlist.pro)
IRAFDIR
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NAME:
IRAFDIR
PURPOSE:
Provide a brief description of the IRAF images on a directory
CALLING SEQUENCE:
IRAFDIR, [ directory, TEXTOUT = ]
OPTIONAL INPUT PARAMETERS:
DIRECTORY - Scalar string giving file name, disk or directory to
be searched
OPTIONAL INPUT KEYWORD:
TEXTOUT - specifies output device (see TEXTOPEN)
textout=1 TERMINAL using /more option
textout=2 TERMINAL without /more option
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file
textout=7 Append to existing .prt file
textout = 'filename' (default extension of .prt)
OUTPUT PARAMETERS:
None
PROCEDURE:
FINDFILE is used to find all '.imh' files in the directory.
The object name and image size (NAXIS1, NAXIS2) are extracted
from the header. Each header is also searched for the parameters
DATE-OBS (or TDATEOBS), TELESCOP (or OBSERVAT), EXPTIME.
RESTRICTIONS:
(1) Some fields may be truncated since IRAFDIR uses a fixed format
output
(2) No more than 2 dimension sizes are displayed
SYSTEM VARIABLES:
If 'textout' keyword is not specified to select an output device,
!TEXTOUT will be the default. This non-standard system variable
can be added using the procedure ASTROLIB.
PROCEDURE CALLS:
EXPAND_TILDE(), FDECOMP, REMCHAR, TEXTOPEN, TEXTCLOSE
MODIFICATION HISTORY:
Written, K. Venkatakrishna, ST Systems Corp, August 1991
Work for IRAF V2.11 format W. Landsman November 1997
Assume since V5.5 use file_search W. Landsman Sep 2006
(See astrolib/pro/irafdir.pro)
IRAFRD
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NAME:
IRAFRD
PURPOSE:
Read an IRAF (.imh) file into IDL image and header arrays.
EXPLANATION:
The internal IRAF format changed somewhat in IRAF V2.11 to a machine
independent format, with longer filename allocations. This version
of IRAFRD should be able to read either format.
CALLING SEQUENCE:
IRAFRD, im, hdr, filename, [/SILENT ]
OPTIONAL INPUT:
FILENAME - Character string giving the name of the IRAF image
header. If omitted, then program will prompt for the
file name. IRAFRD always assumes the header file has an
extension '.imh'. IRAFRD will automatically locate the
".pix" file containing the data by parsing the contents of
the .imh file. (If the parse is unsuccesful, then IRAFRD looks
in the same directory as the .imh file.)
OUTPUTS:
IM - array containing image data
HDR - string array containing header. Basic information in the
IRAF header is converted to a FITS style header
OPTIONAL INPUT KEYWORDS:
/SILENT - If this keyword is set and non-zero, then messages displayed
while reading the image will be suppressed.
RESTRICTIONS:
(1) Image size and history sections of the IRAF header are copied
into the FITS header HDR. Other information (e.g. astrometry)
might not be included unless it is also in the history section
(2) IRAFRD ignores the node name when deciphering the name of the
IRAF ".pix" file.
(3) Certain FITS keywords ( DATATYPE, IRAFNAME) may appear more than
once in the output name
(4) Does not read the DATE keyword for the new (V2.11) IRAF files
NOTES:
IRAFRD obtains dimensions and type of image from the IRAF header.
PROCEDURES CALLED:
FDECOMP, SXADDPAR, SXPAR()
MODIFICATION HISTORY:
Written W. Landsman, STX January 1989
Converted to IDL Version 2. M. Greason, STX, June 1990
Updated for DecStation compatibility W. Landsman March 1992
Don't leave an open LUN W. Landsman July 1993
Don't overwrite existing OBS-DATE W. Landsman October 1994
Don't bomb on very long FITS headers W. Landsman April 1995
Work on Alpha/OSF and Linux W. Landsman Dec 1995
Remove /VMSIMG keyword, improve efficiency when physical and
image dimensions differ W. Landsman April 1996
Don't use FINDFILE (too slow) W. Landsman Oct 1996
Read V2.11 files, remove some parameter checks W. Landsman Nov. 1997
Fixed problem reading V2.11 files with long headers Jan. 1998
Accept names with multiple extensions W. Landsman April 98
Test for big endian machine under V2.11 format W. Landsman Feb. 1999
Don't read past the end of file for V5.4 compatilibity W.L. Jan. 2001
Convert to square brackets W.L May 2001
Assume since V5.4, remove SPEC_DIR() W. L. April 2006
(See astrolib/pro/irafrd.pro)
IRAFWRT
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NAME:
IRAFWRT
PURPOSE:
Write IDL data in IRAF (OIF) format (.imh and .pix files).
EXPLANATION:
Does the reverse of IRAFRD. IRAFWRT writes the "old" IRAF format
used prior to v2.11. However, this "old" format is still readable by
the current version of IRAF.
CALLING SEQUENCE:
IRAFWRT, image, hdr, filename, [ PIXDIR = ]
INPUTS:
image - array containing data
hdr - The corresponding FITS header. Use MKHDR to create a minimal
FITS header if one does not already exist.
filename - Scalar string giving the name of the file to be written
Should not include the extension name, which will be supplied
by IRAFWRT.
OUTPUTS:
None
OPTIONAL KEYWORD INPUT:
PIXDIR - scalar string specifying the directory into which to write
the IRAF pixel (.pix) file. The default is to write the pixel
file to the same directory as the header (.imh) file
SIDE EFFECTS:
Image array and FITS header are written to IRAF pixel file
'filename'.pix and header file 'filename'.imh
EXAMPLE:
Write an empty 50 x 50 array of all zeros to an IRAF file named 'EMPTY'
IDL> im = intarr( 50, 50) ;Create empty array
IDL> mkhdr, hdr, im ;Create a minimal FITS header
IDL> irafwrt, im, hdr, 'empty' ;Write to a IRAF file named 'empty'
PROCEDURE:
IRAFWRT gets information about the data - image dimensions, size,
datatype, maximum and minimum pixel values - and writes it into
the binary part of the header. The ASCII part of the header
is directly copied after deleting records with certain keywords
A pixel file is created, with a header in the first 1024 bytes
RESTRICTIONS:
(1) The files are not created by IRAFWRT are not identical to those
created by the IRAF routine rfits. However, the files
created by IRAFWRT appear to be compatible with all the IRAF
routines tested so far.
(2) IRAFWRT has been tested on a limited number of data types
(3) IRAFWRT has only been tested on Unix and VMS systems.
PROCEDURES CALLED:
FDECOMP, IS_IEEE_BIG(), ISARRAY(), REPCHR(), STRN(), SXDELPAR, SXPAR()
MODIFICATION HISTORY:
Written K. Venkatakrishna, STX February 1992
VMS compatibility W. Landsman April 1992
Work with headers without DATE-OBS or ORIGIN August 1992
Preserve HISTORY records with other FITS records March 1995
Fix case where a minimal FITS header supplied August 1995
Work under Alpha/OSF and Linux Dec. 1995
Make sureheader has 80 char lines, use IS_IEEE_BIG() May 1997
Don't apply strlowcase to .pix name W. Landsman April 1999
Work with double precision W. Landsman May 1999
Minimize use of obsolete !ERR W. Landsman Feb. 2000
Assume since V5.5, remove VMS support W. Landsman Sep. 2006
(See astrolib/pro/irafwrt.pro)
ISMEUV
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NAME:
ISMEUV
PURPOSE:
Compute the continuum interstellar EUV optical depth
EXPLANATION:
The EUV optical depth is computed from the photoionization of
hydrogen and helium.
CALLING SEQUENCE:
tau = ISMEUV( wave, Hcol, [ HeIcol, HeIIcol, /Fano ]
INPUTS:
wave - Vector of wavelength values (in Angstroms). Useful range is
40 - 912 A; at shorter wavelengths metal opacity should be
considered, at longer wavelengths there is no photoionization.
Hcol - Scalar specifying interstellar hydrogen column density in cm-2.
Typical values are 1E17 to 1E20.
OUTPUT:
tau - Vector giving resulting optical depth, same number of elements
as wave, non-negative values. To obtain the attenuation of
an input spectrum, multiply by exp(-tau).
OPTIONAL INPUTS:
HeIcol - Scalar specifying neutral helium column density in cm-2.
Default is 0.1*Hcol (10% of hydrogen column)
HeIIcol - Scalar specifying ionized helium column density in cm-2
Default is 0 (no HeII)
OPTIONAL INPUT KEYWORDS:
/FANO - If this keyword is set and non-zero, then the 4 strongest
auto-ionizing resonances of He I are included. The shape
of these resonances is given by a Fano profile - see Rumph,
Bowyer, & Vennes 1994, AJ, 107, 2108. If these resonances are
included then the input wavelength vector should have
a fine (>~0.01 A) grid between 190 A and 210 A, since the
resonances are very narrow.
EXAMPLE:
(1) One has a model EUV spectrum with wavelength, w (in Angstroms) and
flux,f . Plot the model flux after attenuation by 1e18 cm-2 of HI,
with N(HeI)/N(HI) = N(HeII)/N(HI) = 0.05
IDL> Hcol = 1e18
IDL> plot, w, f*exp(-ismeuv(w, Hcol, .05*Hcol, .05*Hcol))
(2) Plot the cross-section of HeI from 180 A to 220 A for 1e18 cm-2
of HeI, showing the auto-ionizing resonances. This is
Figure 1 in Rumph et al. (1994)
IDL> w = 180 + findgen(40000)*0.001 ;Need a fine wavelength grid
IDL> plot, w, ismeuv(w, 0, 1e18, /Fano)
NOTES:
(1) The more complete program ismtau.pro at
http://hea-www.harvard.edu/PINTofALE/pro/ extends this work
to shorter wavelengths and includes metal and molecular hydrogen
opacities
(2) This program only compute continuum opacities, and for example,
the He ionization edges at 504 A and 228 A are blurred by
converging line absorptions (Dupuis et al. 1995. ApJ, 455, 574)
HISTORY:
Written, W. Landsman October, 1994
Adapted from ism.c at anonymous ftp site cea-ftp.cea.berkeley.edu
by Pat Jelinsky, Todd Rumph & others.
Converted to IDL V5.0 W. Landsman September 1997
Avoid underflow messages, support double prec. W. Landsman October 2003
(See astrolib/pro/ismeuv.pro)
IS_IEEE_BIG
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NAME:
IS_IEEE_BIG
PURPOSE:
Determine if the current machine uses IEEE, big-endian numbers.
EXPLANATION:
(Big endian implies that byteorder XDR conversions are no-ops).
CALLING SEQUENCE:
flag = is_ieee_big()
INPUT PARAMETERS:
None
RETURNS:
1 if the machine appears to be IEEE-compliant, 0 if not.
COMMON BLOCKS:
None.
SIDE EFFECTS:
None
RESTRICTIONS:
PROCEDURE:
The first byte of the two-byte representation of 1 is examined.
If it is zero, then the data is stored in big-endian order.
MODIFICATION HISTORY:
Written 15-April-1996 by T. McGlynn for use in MRDFITS.
13-jul-1997 jkf/acc - added calls to check_math to avoid
underflow messages in V5.0 on Win32 (NT).
Converted to IDL V5.0 W. Landsman September 1997
Follow RSI and just do a single test W. Landsman April 2003
(See astrolib/pro/is_ieee_big.pro)
JDCNV
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NAME:
JDCNV
PURPOSE:
Converts Gregorian dates to Julian days
EXPLANATION:
For IDL versions V5.1 or greater, this procedure is superceded by
JULDAY() function in the standard IDL distribution. Note, however,
that prior to V5.1 there wasa bug in JULDAY() that gave answers off
by 0.5 days.
CALLING SEQUENCE:
JDCNV, YR, MN, DAY, HR, JULIAN
INPUTS:
YR = Year, integer scalar or vector
MN = Month integer (1-12) scalar or vector
DAY = Day integer 1-31) scalar or vector
HR = Hours and fractions of hours of universal time (U.T.), scalar
or vector
OUTPUTS:
JULIAN = Julian date (double precision)
EXAMPLE:
To find the Julian Date at 1978 January 1, 0h (U.T.)
IDL> JDCNV, 1978, 1, 1, 0., JULIAN
will give JULIAN = 2443509.5
NOTES:
(1) JDCNV will accept vector arguments
(2) JULDATE is an alternate procedure to perform the same function
REVISON HISTORY:
Converted to IDL from Don Yeomans Comet Ephemeris Generator,
B. Pfarr, STX, 6/15/88
Converted to IDL V5.0 W. Landsman September 1997
Added checks on valid month, day ranges W. Landsman July 2008
(See astrolib/pro/jdcnv.pro)
JPLEPHINTERP
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NAME:
JPLEPHINTERP
AUTHOR:
Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
[email protected]
UPDATED VERSIONs can be found on my WEB PAGE:
http://cow.physics.wisc.edu/~craigm/idl/idl.html
PURPOSE:
Interpolate position and motion of planetary bodies (JPL Ephemeris)
MAJOR TOPICS:
Planetary Orbits, Interpolation
CALLING SEQUENCE:
JPLEPHINTERP, INFO, RAWDATA, T, X, Y, Z, [VX, VY, VZ, /EARTH, /SUN,
OBJECTNAME=, CENTER=, TBASE=, POSUNITS=, VELUNITS= ]
DESCRIPTION:
JPLEPHINTERP interpolates the JPL DE200 or DE405 planetary
ephemeris to find the positions and motions of planetary bodies.
This routine is the second stage of a two-stage process to
interpolate the JPL ephemeris. In this first stage, the file is
opened using JPLEPHREAD, and the relevant portions of the table
are read and stored into the two variables INFO and RAWDATA. In
the second stage, the user actually interpolates the ephemeris for
the desired bodies and to the desired ephemeris time using
JPLEPHINTERP.
The only independent variable which must be specified is T, the
ephemeris time. For low to moderate accuracy applications, T is
simply the conventional calendar date, expressed in Julian days.
See below for high precision applications.
Upon output, the position components of the desired body are
returned in parameters X, Y and Z, and if requested velocity
components are returned in parameters VX, VY and VZ. Coordinates
are referred to the ephemeris's coordinate system: FK5 for
JPL-DE200 and ICRS for JPL-DE405. By default, the origin of
coordinates is the solar system barycenter (SSB), unless another
origin is selected using the CENTER keyword.
Users must set the VELOCITY keyword to generate body velocities.
By default they are not generated.
Users can select the desired body by using either the EARTH or SUN
keywords, or the OBJECTNAME keyword.
By default, positions are returned in units of KM and velocities
in units of KM/DAY. However, the output units are selectable by
setting the POSUNITS and VELUNITS keywords.
High Precision Applications
If the required precision is finer than a few hundred meters, the
user must be aware that the formal definition of the ephemeris
time is the coordinate time of a clock placed at the solar system
barycenter (SSB). If the user's time is measured by a clock
positioned elsewhere, then various corrections must be applied.
Usually, the most significant correction is that from the
geocenter to the SSB (see Fairhead & Bretagnon 1990; Fukushima
1995). Not applying this correction creates an error with
amplitude ~170 nano-light-seconds ( = 50 m) on the earth's
position. (see TDB2TDT)
For high precision, the user should also specify the TBASE
keyword. TBASE should be considered a fixed epoch with respect to
which T is measured; T should be small compared to TBASE.
Internally, subtraction of large numbers occurs with TBASE first,
so truncation error is minimized by specifying TBASE.
Nutations and Librations
This routine also provides information about earth nutations and
lunar librations, which are stored in the JPL ephemeris tables.
The POSUNITS and VELUNITS keywords do not affect these
computations.
Lunar librations in the form of three Euler angles are returned in
X, Y, Z, in units of radians, and their time derivatives are
returned in VX, VY, and VZ in units of radians per day.
The earth nutation angles psi (nutation in longitude) and epsilon
(nutation in obliquity) are returned in X and Y, in units of
radians. Their time derivatives are returned in VX and VY
respectively. The quantities returned in Z and VZ are undefined.
Verification
The precision routine has been verified using JPLEPHTEST, which is
similar to the original JPL program EPHTEST. For years 1950 to
2050, JPLEPHINTERP reproduces the original JPL ephemeris to within
1 centimeter.
Custom Ephemerides
It is possible to make custom ephemerides using JPLEPHMAKE, or to
augmented an existing ephemeris with additional data. In the
former case JPLEPHINTERP should automatically choose the correct
object from the table and interpolate it appropriately.
For augmented ephemerides, the object can be specified by name,
which works as expected, or by number, which has a special
behavior. For augmented files only, the new objects begin at
number 100.
PARAMETERS:
INFO - structure returned by JPLEPHREAD. Users should not modify
this structure.
RAWDATA - raw data array returned by JPLEPHREAD. Users should not
modify this data array.
T - ephemeris time(s) of interest, relative to TBASE (i.e. the
actual interpolation time is (T+TBASE)). May be a scalar or
vector.
X, Y, Z - upon return, the x-, y- and z-components of the body
position are returned in these parameters. For
nutations and librations see above.
VX, VY, VZ - upon return, the x-, y- and z-components of the body
velocity are returned in these parameters, if the
VELOCITY keyword is set. For nutations and
librations see above.
KEYWORD PARAMETERS:
EARTH, SUN - set one of these keywords if the desired body is the
earth or the sun. One of EARTH, SUN or OBJECTNAME
must be specified.
OBJECTNAME - a scalar string or integer, specifies the planetary
body of interest. May take any one of the following
integer or string values.
1 - 'MERCURY' 9 - 'PLUTO'
2 - 'VENUS' 10 - 'MOON' (earth's moon)
3 - 'EARTH' 11 - 'SUN'
4 - 'MARS' 12 - 'SOLARBARY' or 'SSB' (solar system barycenter)
5 - 'JUPITER' 13 - 'EARTHBARY' or 'EMB' (earth-moon barycenter)
6 - 'SATURN' 14 - 'NUTATIONS' (see above)
7 - 'URANUS' 15 - 'LIBRATIONS' (see above)
8 - 'NEPTUNE'
For custom ephemerides, the user should specify the
object name or number.
For augmented ephemerides, the user should specify
the name. If the number is specified, then numbers
1-15 have the above meanings, and new objects are
numbered starting at 100.
CENTER - a scalar string or integer, specifies the origin of
coordinates. See OBJECTNAME for allowed values.
Default: 12 (Solar system barycenter)
VELOCITY - if set, body velocities are generated and returned in
VX, VY and VZ.
Default: unset (no velocities)
POSUNITS - a scalar string specifying the desired units for X, Y,
and Z. Allowed values:
'KM' - kilometers (default)
'CM' - centimeters
'AU' - astronomical units
'LT-S' - light seconds
If angles are requested, this keyword is ignored and
the units are always 'RADIANS'.
VELUNITS - a scalar string specifying the desired units for VX, VY
and VZ. Allowed values:
'KM/DAY' - kilometers per day (default)
'KM/S' - kilometers per second
'CM/S' - centimeters per second
'LT-S/S' - light seconds per second
'AU/DAY' - astronomical units per day
TBASE - a scalar or vector, specifies a fixed epoch against wich T
is measured. The ephemeris time will be (T+TBASE). Use
this keyword for maximum precision.
EXAMPLE:
Find position of earth at ephemeris time 2451544.5 JD. Units are
in Astronomical Units.
JPLEPHREAD, 'JPLEPH.200', pinfo, pdata, [2451544D, 2451545D]
JPLEPHINTERP, pinfo, pdata, 2451544.5D, xearth, yearth, zearth, $
/EARTH, posunits='AU'
REFERENCES:
AXBARY, Arnold Rots.
ftp://heasarc.gsfc.nasa.gov/xte/calib_data/clock/bary/
HORIZONS, JPL Web-based ephermis calculator (Ephemeris DE406)
http://ssd.jpl.nasa.gov/horizons.html
Fairhead, L. & Bretagnon, P. 1990, A&A, 229, 240
Fukushima, T. 1995, A&A, 294, 895
Standish, E.M. 1982, "Orientation of the JPL Ephemerides,
DE200/LE200, to the Dynamical Equinox of J2000", Astronomy &
Astrophysics, vol. 114, pp. 297-302.
Standish, E.M.: 1990, "The Observational Basis for JPL's DE200,
the planetary ephemeris of the Astronomical Almanac", Astronomy
& Astrophysics, vol. 233, pp. 252-271.
SEE ALSO
JPLEPHREAD, JPLEPHINTERP, JPLEPHTEST, TDB2TDT, JPLEPHMAKE
MODIFICATION HISTORY:
Written and Documented, CM, Jun 2001
Corrected bug in name conversion of NUTATIONS and LIBRATIONS, 18
Oct 2001, CM
Added code to handle custom-built ephemerides, 04 Mar 2002, CM
Fix bug in evaluation of velocity (only appears in highest order
polynomial term); JPLEPHTEST verification tests still pass;
change is of order < 0.5 cm in position, 22 Nov 2004, CM
Perform more validity checking on inputs; and more informative
outputs, 09 Oct 2008, CM
Allow SSB and EMB as shortcuts for solar system and earth-moon
bary center, 15 Oct 2008, CM
TBASE now allowed to be a vector or scalar, 01 Jan 2009, CM
VELFAC keyword gives scale factor between POSUNITS and VELUNITS,
12 Jan 2009, CM
$Id: jplephinterp.pro,v 1.18 2009/01/13 04:53:26 craigm Exp $
(See astrolib/pro/jplephinterp.pro)
JPLEPHREAD
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NAME:
JPLEPHREAD
AUTHOR:
Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
[email protected]
UPDATED VERSIONs can be found on my WEB PAGE:
http://cow.physics.wisc.edu/~craigm/idl/idl.html
PURPOSE:
Open and read JPL DE200 or DE405 Ephemeride FITS File
MAJOR TOPICS:
Planetary Orbits, Interpolation
CALLING SEQUENCE:
JPLEPHREAD, FILENAME, INFO, RAWDATA, JDLIMITS, STATUS=, ERRMSG=
DESCRIPTION:
JPLEPHREAD opens and reads the JPL DE200 or DE405 planetary
ephemerides, as available in FITS format. The user must have the
IDL Astronomy Library installed to use this routine.
This routine is the initialization stage of a two-stage process to
interpolate the JPL ephemeris. In this first stage, the file is
opened, and the relevant portions of the table are read and stored
into the two variables INFO and RAWDATA. In the second stage, the
user actually interpolates the ephemeris for the desired bodies
and to the desired ephemeris time using JPLEPHINTERP.
Users must decide ahead of time the approximate dates of interest,
and pass this range in the JDLIMITS parameter. Any date covered
by the ephemeris is valid.
JPLEPHREAD is able to read files of the following format:
DE200 - Chebyshev - FITS format - Note 1
DE405 - Chebyshev - FITS format - Note 1
DE200 - Taylor - FITS format - Note 2
Note 1 - Chebyshev formatted FITS files are available in the
AXBARY package by Arnold Rots, found here:
ftp://heasarc.gsfc.nasa.gov/xte/calib_data/clock/bary/
or at the Markwardt FTP site:
ftp://cow.physics.wisc.edu/pub/craigm/bary/
Note 2 - Taylor-series based ephemerides have been available for
years in the FTOOLS / LHEASOFT package produced by NASA's
Goddard Space Flight Center. The original file is
de200_new.fits, which covers the years 1959-2000,
inclusive. A newer file is named
de200_1950-2050_v2.fits, and covers the years 1959-2050.
See Markwardt FTP site for these files.
PARAMETERS:
FILENAME - name of ephemeris file (scalar string).
INFO - upon completion, information about the ephemeris data is
returned in this parameter in the form of a structure.
Users must not modify INFO, although several fields are
useful and may be accessed read-only:
TSTART/TSTOP (start and stop time of data in Julian
days);
C (speed of light in km/s);
DENUM (development ephemeris number [200 or 405])
AU (1 astronomical unit, in units of light-seconds)
RAWDATA - upon completion, raw ephemeris data is returned in this
parameter. Users are not meant to access this data
directly, but rather to pass it to JPLEPHINTERP.
JDLIMITS - a two-element vector (optional), describing the desired
time range of interest. The vector should have the
form [TSTART, TSTOP], where TSTART and TSTOP are the
beginning and ending times of the range, expressed in
Julian days.
Default: entire table is read (note, this can be
several megabytes)
KEYWORD PARAMETERS:
STATUS - upon completion, a value of 1 indicates success, and 0
indicates failure.
ERRMSG - upon completion, an error message is returned in this
keyword. If there were no errors, then the returned
value is the empty string, ''.
EXAMPLE:
Find position of earth at ephemeris time 2451544.5 JD. Units are
in Astronomical Units.
JPLEPHREAD, 'JPLEPH.200', pinfo, pdata, [2451544D, 2451545D]
JPLEPHINTERP, pinfo, pdata, 2451544.5D, xearth, yearth, zearth, $
/EARTH, posunits='AU'
REFERENCES:
AXBARY, Arnold Rots.
ftp://heasarc.gsfc.nasa.gov/xte/calib_data/clock/bary/
HORIZONS, JPL Web-based ephermis calculator (Ephemeris DE406)
http://ssd.jpl.nasa.gov/horizons.html
JPL Export Ephemeris FTP Site
ftp://ssd.jpl.nasa.gov/pub/eph/planets/
(ephemeris files are available here, however, they must be
converted to FITS format using the "bin2eph" utility found in
AXBARY)
JPL Export Ephemeris CD-ROM - Ordering Information
http://www.willbell.com/software/jpl.htm
Standish, E.M. 1982, "Orientation of the JPL Ephemerides,
DE200/LE200, to the Dynamical Equinox of J2000", Astronomy &
Astrophysics, vol. 114, pp. 297-302.
Standish, E.M.: 1990, "The Observational Basis for JPL's DE200,
the planetary ephemeris of the Astronomical Almanac", Astronomy
& Astrophysics, vol. 233, pp. 252-271.
SEE ALSO
JPLEPHREAD, JPLEPHINTERP, JPLEPHTEST
PROCEDURES USED:
FXBCLOSE, FXBOPEN, FXPAR(),
MODIFICATION HISTORY:
Written and Documented, CM, Jun 2001
Use GETTOK() instead of STR_SEP() W. Landsman July 2002
$Id: jplephread.pro,v 1.6 2001/07/01 03:32:02 craigm Exp $
(See astrolib/pro/jplephread.pro)
JPLEPHTEST
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NAME:
JPLEPHTEST
AUTHOR:
Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
[email protected]
UPDATED VERSIONs can be found on my WEB PAGE:
http://cow.physics.wisc.edu/~craigm/idl/idl.html
PURPOSE:
Test JPLEPHTEST with JPL test data set
MAJOR TOPICS:
Planetary Orbits, Interpolation
CALLING SEQUENCE:
JPLEPHTEST, EPHFILE, TESTFILE
DESCRIPTION:
JPLEPHTEST tests the JPLEPHINTERP procedure for precision. In
order to function, you must have a JPL ephemeris test data set.
The test data set testpo.405 is available in
ftp://idlastro.gsfc.nasa.gov/pub/data
The procedure opens and reads the test set, which contains
precomputed data. Every tenth value is printed on the screen.
Any deviations that exceed 1.5d-13 AU = 1.5 cm are reported.
The columns are labelled according to the input file, except for
the final column, which is the deviation between the input file
and the computed value.
PARAMETERS:
EPHFILE - a scalar string, specifies the name of the ephemeris
file, in FITS format. JPLEPHTEST will look in the directory
$ASTRO_DATA for the file if it is not in the current directory.
TESTFILE - a scalar string, specifies JPL test data set to compare
against. JPLEPHTEST will look in the directory
$ASTRO_DATA for the file if it is not in the current directory.
EXAMPLE:
Test JPL DE200 and DE405 ephemerides. Assumes files are in the
current directory.
JPLEPHTEST, 'JPLEPH.200', 'testpo.200'
JPLEPHTEST, 'JPLEPH.405', 'testpo.405'
REFERENCES:
JPL Export Ephemeris FTP Site
ftp://ssd.jpl.nasa.gov/pub/eph/planets/
(see test-data/ for test data sets)
HORIZONS, JPL Web-based ephermis calculator (Ephemeris DE406)
http://ssd.jpl.nasa.gov/horizons.html
SEE ALSO
JPLEPHREAD, JPLEPHINTERP, JPLEPHTEST
MODIFICATION HISTORY:
Written and Documented, CM, Jun 2001
Removed TRANSREAD, improved output, improved docs, CM, 9 Jul 2001
$Id: jplephtest.pro,v 1.4 2001/07/20 13:29:53 craigm Exp $
(See astrolib/pro/jplephtest.pro)
JPRECESS
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NAME:
JPRECESS
PURPOSE:
Precess astronomical coordinates from B1950 to J2000
EXPLANATION:
Calculate the mean place of a star at J2000.0 on the FK5 system from the
mean place at B1950.0 on the FK4 system.
Use BPRECESS for the reverse direction J2000 ==> B1950
CALLING SEQUENCE:
jprecess, ra, dec, ra_2000, dec_2000, [ MU_RADEC = , PARALLAX =
RAD_VEL =, EPOCH = ]
INPUTS:
RA,DEC - input B1950 right ascension and declination in *degrees*.
Scalar or vector
OUTPUTS:
RA_2000, DEC_2000 - the corresponding J2000 right ascension and
declination in *degrees*. Same number of elements as RA,DEC
but always double precision.
OPTIONAL INPUT-OUTPUT KEYWORDS
MU_RADEC - 2xN element double precision vector containing the proper
motion in seconds of arc per tropical *century* in right
ascension and declination.
PARALLAX - N_element vector giving stellar parallax (seconds of arc)
RAD_VEL - N_element vector giving radial velocity in km/s
The values of MU_RADEC, PARALLAX, and RADVEL will all be modified
upon output to contain the values of these quantities in the
J2000 system. Values will also be converted to double precision.
The parallax and radial velocity will have a very minor influence on
the J2000 position.
EPOCH - scalar giving epoch of original observations, default 1950.0d
This keyword value is only used if the MU_RADEC keyword is not set.
NOTES:
The algorithm is taken from the Explanatory Supplement to the
Astronomical Almanac 1992, page 184.
Also see Aoki et al (1983), A&A, 128,263
JPRECESS distinguishes between the following two cases:
(1) The proper motion is known and non-zero
(2) the proper motion is unknown or known to be exactly zero (i.e.
extragalactic radio sources). In this case, the algorithm
in Appendix 2 of Aoki et al. (1983) is used to ensure that
the output proper motion is exactly zero. Better precision
can be achieved in this case by inputting the EPOCH of the
original observations.
The error in using the IDL procedure PRECESS for converting between
B1950 and J2000 can be up to 12", mainly in right ascension. If
better accuracy than this is needed then JPRECESS should be used.
EXAMPLE:
The SAO catalogue gives the B1950 position and proper motion for the
star HD 119288. Find the J2000 position.
RA(1950) = 13h 39m 44.526s Dec(1950) = 8d 38' 28.63''
Mu(RA) = -.0259 s/yr Mu(Dec) = -.093 ''/yr
IDL> mu_radec = 100D* [ -15D*.0259, -0.093 ]
IDL> ra = ten(13,39,44.526)*15.D
IDL> dec = ten(8,38,28.63)
IDL> jprecess, ra, dec, ra2000, dec2000, mu_radec = mu_radec
IDL> print, adstring(ra2000, dec2000,2)
===> 13h 42m 12.740s +08d 23' 17.69"
RESTRICTIONS:
"When transferring individual observations, as opposed to catalog mean
place, the safest method is to tranform the observations back to the
epoch of the observation, on the FK4 system (or in the system that was
used to to produce the observed mean place), convert to the FK5 system,
and transform to the the epoch and equinox of J2000.0" -- from the
Explanatory Supplement (1992), p. 180
REVISION HISTORY:
Written, W. Landsman September, 1992
Corrected a couple of typos in M matrix October, 1992
Vectorized, W. Landsman February, 1994
Implement Appendix 2 of Aoki et al. (1983) for case where proper
motion unknown or exactly zero W. Landsman November, 1994
Converted to IDL V5.0 W. Landsman September 1997
Fixed typo in updating proper motion W. Landsman April 1999
Make sure proper motion is floating point W. Landsman December 2000
Use V6.0 notation W. Landsman Mar 2011
(See astrolib/pro/jprecess.pro)
JULDATE
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NAME:
JULDATE
PURPOSE:
Convert from calendar to Reduced Julian Date
EXPLANATION:
Julian Day Number is a count of days elapsed since Greenwich mean noon
on 1 January 4713 B.C. The Julian Date is the Julian day number
followed by the fraction of the day elapsed since the preceding noon.
This procedure duplicates the functionality of the JULDAY() function in
in the standard IDL distribution, but also allows interactive input and
gives output as Reduced Julian date (=JD - 2400000.)
CALLING SEQUENCE:
JULDATE, /PROMPT ;Prompt for calendar Date, print Julian Date
or
JULDATE, date, jd
INPUT:
DATE - 3 to 6-element vector containing year,month (1-12),day, and
optionally hour, minute, and second all specified as numbers
(Universal Time). Year should be supplied with all digits.
Years B.C should be entered as negative numbers (and note that
Year 0 did not exist). If Hour, minute or seconds are not
supplied, they will default to 0.
OUTPUT:
JD - Reduced Julian date, double precision scalar. To convert to
Julian Date, add 2400000. JULDATE will print the value of
JD at the terminal if less than 2 parameters are supplied, or
if the /PROMPT keyword is set
OPTIONAL INPUT KEYWORD:
/PROMPT - If this keyword is set and non-zero, then JULDATE will prompt
for the calendar date at the terminal.
RESTRICTIONS:
The procedure HELIO_JD can be used after JULDATE, if a heliocentric
Julian date is required.
EXAMPLE:
A date of 25-DEC-2006 06:25 UT may be expressed as either
IDL> juldate, [2006, 12, 25, 6, 25], jd
IDL> juldate, [2006, 12, 25.2673611d], jd
In either case, one should obtain a Reduced Julian date of
JD = 54094.7673611
PROCEDURE USED:
GETOPT()
REVISION HISTORY
Adapted from IUE RDAF (S. Parsons) 8-31-87
Algorithm from Sky and Telescope April 1981
Added /PROMPT keyword, W. Landsman September 1992
Converted to IDL V5.0 W. Landsman September 1997
Make negative years correspond to B.C. (no year 0), work for year 1582
Disallow 2 digit years. W. Landsman March 2000
(See astrolib/pro/juldate.pro)
KSONE
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NAME:
KSONE
PURPOSE:
Compute the one-sided Kolmogorov-Smirnov statistic
EXPLANATION:
Returns the Kolmogorov-Smirnov statistic and associated probability for
for an array of data values and a user-supplied cumulative distribution
function (CDF) of a single variable. Algorithm from the procedure of
the same name in "Numerical Recipes" by Press et al. 2nd edition (1992)
CALLING SEQUENCE:
ksone, data, func_name, D, prob, [ /PLOT ]
INPUT PARAMETERS:
data - vector of data values, must contain at least 4 elements for the
K-S statistic to be meaningful
func_name - scalar string giving the name of the cumulative distribution
function. The function must be defined to accept the data
vector as its only input (see example), though keywords may be
passed via the _EXTRA facility.
OUTPUT PARAMETERS:
D - floating scalar giving the Kolmogorov-Smirnov statistic. It
specified the maximum deviation between the cumulative
distribution of the data and the supplied function
prob - floating scalar between 0 and 1 giving the significance level of
the K-S statistic. Small values of PROB show that the
cumulative distribution function of DATA is significantly
different from FUNC_NAME.
OPTIONAL INPUT KEYWORD:
/PLOT - If this keyword is set and non-zero, then KSONE will display a
plot of the CDF of the data with the supplied function
superposed. The data value where the K-S statistic is
computed (i.e. at the maximum difference between the data CDF
and the function) is indicated by a vertical line.
KSONE accepts the _EXTRA keyword, so that most plot keywords
(e.g. TITLE, XTITLE, XSTYLE) can also be passed to KSONE.
/WINDOW - If set, the plot to a resizeable graphics window
EXAMPLE:
Determine if a vector created by the RANDOMN function is really
consistent with a Gaussian distribution with unit variance.
The CDF of a Gaussian is the error function except that a factor
of 2 is included in the error function. So we must create a special
function:
function gauss_cdf, x
return, errorf( x/sqrt(2) )
end
IDL> data = randomn(seed, 50) ;create data array to be tested
IDL> ksone, abs(data), 'gauss_cdf', D, prob, /PLOT ;Use K-S test
A small value of PROB indicates that the cumulative distribution of
DATA is significantly different from a Gaussian
NOTES:
The code for PROB_KS is from the 2nd (1992) edition of Numerical
Recipes which includes a more accurate computation of the K-S
significance for small values of N than the first edition.
Since _EXTRA is used to pass extra parameters both to the user-supplied
function, and to the cgPLOT command, the user-supplied function should
not accept "cgPLOT" keyword names (e.g. XTITLE).
PROCEDURE CALLS
procedure PROB_KS - computes significance of K-S distribution
TAG_EXIST()
REVISION HISTORY:
Written W. Landsman August, 1992
Accept _EXTRA keywords W. Landsman September, 1995
Fixed possible bug in plot display showing position maximum difference
in histogram M. Fardal/ W. Landsman March, 1997
Documentation updates W. Landsman June 2003
Pass _EXTRA to func_name M. Fitzgerald April, 2005
Work for functions that do not accept keywords W. Landsman July 2009
Use Coyote graphics for plotting Feb 2011
(See astrolib/pro/ksone.pro)
KSTWO
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NAME:
KSTWO
PURPOSE:
Return the two-sided Kolmogorov-Smirnov statistic
EXPLANATION:
Returns the Kolmogorov-Smirnov statistic and associated probability
that two arrays of data values are drawn from the same distribution
Algorithm taken from procedure of the same name in "Numerical
Recipes" by Press et al., 2nd edition (1992), Chapter 14
CALLING SEQUENCE:
kstwo, data1, data2, D, prob
INPUT PARAMATERS:
data1 - vector of data values, at least 4 data values must be included
for the K-S statistic to be meaningful
data2 - second set of data values, does not need to have the same
number of elements as data1
OUTPUT PARAMETERS:
D - floating scalar giving the Kolmogorov-Smirnov statistic. It
specifies the maximum deviation between the cumulative
distribution of the data and the supplied function
prob - floating scalar between 0 and 1 giving the significance level of
the K-S statistic. Small values of PROB show that the
cumulative distribution function of DATA1 is significantly
different from DATA2
EXAMPLE:
Test whether two vectors created by the RANDOMN function likely came
from the same distribution
IDL> data1 = randomn(seed,40) ;Create data vectors to be
IDL> data2 = randomn(seed,70) ;compared
IDL> kstwo, data1, data2, D, prob & print,D,prob
PROCEDURE CALLS
procedure PROB_KS - computes significance of K-S distribution
REVISION HISTORY:
Written W. Landsman August, 1992
FP computation of N_eff H. Ebeling/W. Landsman March 1996
Fix for arrays containing equal values J. Ballet/W. Landsman Oct. 2001
Fix index when maximum difference is at array end Renbin Yan Dec 2008
Handle large number when computing N_err D. Schnitzeler/WL Sep 2010
(See astrolib/pro/kstwo.pro)
KUIPERONE
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NAME:
KUIPERONE
PURPOSE:
Compute the one-sided Kuiper statistic (invariant Kolmogorov-Smirnov)
EXPLANATION:
Returns the Kuiper statistic and associated probability
for an array of data values and a user-supplied cumulative distribution
function (CDF) of a single variable. Algorithm adapted from KSONE
in "Numerical Recipes" by Press et al. 2nd edition (1992)
Kuiper's test is especially useful for data defined on a circle or
to search for periodicity (see Paltani 2004, A&A, 420, 789).
CALLING SEQUENCE:
kuiperone, data, func_name, D, prob, [ /PLOT ]
INPUT PARAMETERS:
data - vector of data values, must contain at least 4 elements for the
Kuiper statistic to be meaningful
func_name - scalar string giving the name of the cumulative distribution
function. The function must be defined to accept the data
vector as its only input (see example).
OUTPUT PARAMETERS:
D - floating scalar giving the Kuiper statistic. It
specifies the sum of positive and negative deviations between the
cumulative distribution of the data and the supplied function
prob - floating scalar between 0 and 1 giving the significance level of
the Kuiper statistic. Small values of PROB show that the
cumulative distribution function of DATA is significantly
different from FUNC_NAME.
OPTIONAL INPUT KEYWORD:
/PLOT - If this keyword is set and non-zero, then KUIPERONE will display a
plot of the CDF of the data with the supplied function
superposed. The data values where the Kuiper statistic is
computed (i.e. at the maximum difference between the data CDF
and the function) are indicated by vertical dashed lines.
KUIPERONE accepts the _EXTRA keyword, so that most plot keywords
(e.g. TITLE, XTITLE, XSTYLE) can also be passed to KUIPERONE.
EXAMPLE:
Determine if a vector created by the RANDOMN function is really
consistent with a Gaussian distribution.
The CDF of a Gaussian is the error function except that a factor
of 2 is included in the error function. So we must create a special
function:
function gauss_cdf, x
return, errorf( x/sqrt(2) )
end
IDL> data = randomn(seed, 50) ;create data array to be tested
IDL> kuiperone, data, 'gauss_pdf', D, prob, /PLOT ;Use Kuiper test
A small value of PROB indicates that the cumulative distribution of
DATA is significantly different from a Gaussian
NOTES:
Note that the 2nd (1992) edition of Numerical Recipes includes
a more accurate computation of the K-S significance for small
values of N.
PROCEDURE CALLS
procedure PROB_KUIPER - computes significance of Kuiper distribution
REVISION HISTORY:
Written W. Landsman August, 1992
Accept _EXTRA keywords W. Landsman September, 1995
Fixed possible bug in plot display showing position maximum difference
in histogram M. Fardal/ W. Landsman March, 1997
Adapted from KSONE J. Ballet July 2003
Use Coyote graphics W. Landsman Feb 2011
(See astrolib/pro/kuiperone.pro)
KUIPERTWO
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NAME:
KUIPERTWO
PURPOSE:
Compute the two-sided Kuiper statistic (invariant Kolmogorov-Smirnov)
EXPLANATION:
Returns the Kuiper statistic and associated probability
that two arrays of data values are drawn from the same distribution
Algorithm adapted from KSTWO in "Numerical
Recipes" by Press et al., 2nd edition (1992), Chapter 14
CALLING SEQUENCE:
kuipertwo, data1, data2, D, prob, [ /PLOT ]
INPUT PARAMETERS:
data1 - vector of data values, at least 4 data values must be included
for the Kuiper statistic to be meaningful
data2 - second set of data values, does not need to have the same
number of elements as data1
OUTPUT PARAMETERS:
D - floating scalar giving the Kuiper statistic. It
specifies the sum of positive and negative deviations between
the cumulative distributions of the two data sets
prob - floating scalar between 0 and 1 giving the significance level of
the Kuiper statistic. Small values of PROB show that the
cumulative distribution function of DATA1 is significantly
different from DATA2
OPTIONAL INPUT KEYWORD:
/PLOT - If this keyword is set and non-zero, then KUIPERTWO will display
a plot of the CDF of the two data sets.
The data values where the Kuiper statistic is
computed (i.e. at the maximum difference between the CDF of
the two data sets) are indicated by vertical dashed lines.
KUIPERTWO accepts the _EXTRA keyword, so that most plot keywords
(e.g. TITLE, XTITLE, XSTYLE) can also be passed to KUIPERTWO.
/WINDOW - If set the plot to a resizeable graphics window.
EXAMPLE:
Test whether two vectors created by the RANDOMN function likely came
from the same distribution
IDL> data1 = randomn(seed,40) ;Create data vectors to be
IDL> data2 = randomn(seed,70) ;compared
IDL> kuipertwo, data1, data2, D, prob & print,D,prob
PROCEDURE CALLS
procedure PROB_KUIPER - computes significance of Kuiper distribution
REVISION HISTORY:
Written W. Landsman August, 1992
FP computation of N_eff H. Ebeling/W. Landsman March 1996
Fix for arrays containing equal values J. Ballet/W. Landsman
Oct. 2001
Adapted from KSTWO, added PLOT keyword J. Ballet July 2004
Use Coyote Graphics W. Landsman Feb 2011
(See astrolib/pro/kuipertwo.pro)
LINEID_PLOT
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NAME:
LINEID_PLOT
PURPOSE:
Plot spectrum with specified line identifications annotated at the
top of the plot.
CALLING SEQUENCE:
lineid_plot, wave, flux, wline, text1, [ text2,
LCHARSIZE=, LCHARTHICK=, EXTEND =, ...plotting keywords]
INPUTS:
wave - wavelength vector for the plot
flux - flux vector
wline - wavelength vector of line identifications. (only the lines
between the plot limits will be used)
text1 - string array of text to be used to annotate each line
text2 - (OPTIONAL) second string array of text to be used for
line annotation. Since the text is written with
proportional spaced characters, TEXT2 can be used if
you want two sets of annotation to be alinged:
eg: Cr IV 1390.009
Fe V 1390.049
Ni IV 1390.184
instead of
Cr IV 1390.009
Fe V 1390.049
Ni IV 1390.184
OPTIONAL KEYWORD INPUTS:
EXTEND - specifies that the annotated lines should have a dotted line
extended to the spectrum to indicate the line position.
EXTEND can be a scalar (applies to all lines) or a vector with
a different value for each line. The value of EXTEND gives
the line IDL plot line thickness for the dotted lines.
If EXTEND is a vector each dotted line can have a different
thickness. A value of 0 indicates that no dotted line is to
be drawn. (default = scalar 0)
LCHARSIZE - the character size of the annotation for each line.
If can be a vector so that different lines are annotated with
different size characters. LCHARSIZE can be used to make
stronger lines have a larger annotation. (default = scalar 1.0).
LCHARTHICK = the character thickness of the annotation for each line.
It can be a vector so that different lines are annotated with
characters of varying thickness. LCHARTHICK can be used to
make stronger lines have a bolder annotation.
(default = !p.charthick)
LINEID_PLOT uses the _EXTRA facility to allow the use of any cgPLOT
keywords (e.g. AXISCOLOR, LINESTYLE, CHARSIZE) to be passed to the
plot.
SIDE EFFECTS:
Program uses SET_VIEWPORT to set the !P.POSITION parameter to allow
room for the annotation. This system variable can be reset to the
default value by setting !P.POSTION=0 or typing SET_VIEWPORT with no
parameters
OPERATIONAL NOTES:
Once the program has completed, You can use OPLOT to draw additional
plots on the display.
If your annotated characters are not being rotated properly,
try setting !P.FONT to a non zero value.
EXAMPLE:
Annotate some interstellar lines between 1240 and 1270 A.
IDL> w = 1240+ indgen(300)*0.1 ;Make a wavelength vector
IDL> f = randomn(seed,300) ;Random flux vector
IDL> id = ['N V','Si II','Si II','Si II'] ;Line IDs
IDL> wl = [1242.80,1260.42,1264.74,1265.00] ;Line positions
IDL> lineid_plot,w,f,wl,id,wl,/ext
Note that LINEID_PLOT is smart enough not to overlap the annotation
for the two closely spaced lines at 1264.74 and 1265.00
HISTORY:
version 1 D. Lindler Jan, 1992
Sept 27, 1993 DJL fixed bug in /extend option
Apr 19, 1994 DJL corrected bug in sorting of charthick (cthick)
Sep 1996, W. Landsman, added _EXTRA keyword, changed keyword names
CHARTHICK==>LCHARTHICK, CHARSIZE==>LCHARSIZE
Work with !P.MULTI W. Landsman December 2003
Use Coyote graphics routines W. Landsman February 2011
(See astrolib/pro/lineid_plot.pro)
LINMIX_ERR
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NAME:
LINMIX_ERR
PURPOSE:
Bayesian approach to linear regression with errors in both X and Y
EXPLANATION:
Perform linear regression of y on x when there are measurement
errors in both variables. the regression assumes :
ETA = ALPHA + BETA * XI + EPSILON
X = XI + XERR
Y = ETA + YERR
Here, (ALPHA, BETA) are the regression coefficients, EPSILON is the
intrinsic random scatter about the regression, XERR is the
measurement error in X, and YERR is the measurement error in
Y. EPSILON is assumed to be normally-distributed with mean zero and
variance SIGSQR. XERR and YERR are assumed to be
normally-distributed with means equal to zero, variances XSIG^2 and
YSIG^2, respectively, and covariance XYCOV. The distribution of XI
is modelled as a mixture of normals, with group proportions PI,
mean MU, and variance TAUSQR. Bayesian inference is employed, and
a structure containing random draws from the posterior is
returned. Convergence of the MCMC to the posterior is monitored
using the potential scale reduction factor (RHAT, Gelman et
al.2004). In general, when RHAT < 1.1 then approximate convergence
is reached.
Simple non-detections on y may also be included.
CALLING SEQUENCE:
LINMIX_ERR, X, Y, POST, XSIG=, YSIG=, XYCOV=, DELTA=, NGAUSS=, /SILENT,
/METRO, MINITER= , MAXITER=
INPUTS :
X - THE OBSERVED INDEPENDENT VARIABLE. THIS SHOULD BE AN
NX-ELEMENT VECTOR.
Y - THE OBSERVED DEPENDENT VARIABLE. THIS SHOULD BE AN NX-ELEMENT
VECTOR.
OPTIONAL INPUTS :
XSIG - THE 1-SIGMA MEASUREMENT ERRORS IN X, AN NX-ELEMENT VECTOR.
YSIG - THE 1-SIGMA MEASUREMENT ERRORS IN Y, AN NX-ELEMENT VECTOR.
XYCOV - THE COVARIANCE BETWEEN THE MEASUREMENT ERRORS IN X AND Y,
AND NX-ELEMENT VECTOR.
DELTA - AN NX-ELEMENT VECTOR INDICATING WHETHER A DATA POINT IS
CENSORED OR NOT. IF DELTA[i] = 1, THEN THE SOURCE IS
DETECTED, ELSE IF DELTA[i] = 0 THE SOURCE IS NOT DETECTED
AND Y[i] SHOULD BE AN UPPER LIMIT ON Y[i]. NOTE THAT IF
THERE ARE CENSORED DATA POINTS, THEN THE
MAXIMUM-LIKELIHOOD ESTIMATE (THETA) IS NOT VALID. THE
DEFAULT IS TO ASSUME ALL DATA POINTS ARE DETECTED, IE,
DELTA = REPLICATE(1, NX).
METRO - IF METRO = 1, THEN THE MARKOV CHAINS WILL BE CREATED USING
THE METROPOLIS-HASTINGS ALGORITHM INSTEAD OF THE GIBBS
SAMPLER. THIS CAN HELP THE CHAINS CONVERGE WHEN THE SAMPLE
SIZE IS SMALL OR IF THE MEASUREMENT ERRORS DOMINATE THE
SCATTER IN X AND Y.
SILENT - SUPPRESS TEXT OUTPUT.
MINITER - MINIMUM NUMBER OF ITERATIONS PERFORMED BY THE GIBBS
SAMPLER OR METROPOLIS-HASTINGS ALGORITHM. IN GENERAL,
MINITER = 5000 SHOULD BE SUFFICIENT FOR CONVERGENCE. THE
DEFAULT IS MINITER = 5000. THE MCMC IS STOPPED AFTER
RHAT < 1.1 FOR ALL PARAMETERS OF INTEREST, AND THE
NUMBER OF ITERATIONS PERFORMED IS GREATER THAN MINITER.
MAXITER - THE MAXIMUM NUMBER OF ITERATIONS PERFORMED BY THE
MCMC. THE DEFAULT IS 1D5. THE MCMC IS STOPPED
AUTOMATICALLY AFTER MAXITER ITERATIONS.
NGAUSS - THE NUMBER OF GAUSSIANS TO USE IN THE MIXTURE
MODELLING. THE DEFAULT IS 3. IF NGAUSS = 1, THEN THE
PRIOR ON (MU, TAUSQR) IS ASSUMED TO BE UNIFORM.
OUTPUT :
POST - A STRUCTURE CONTAINING THE RESULTS FROM THE MCMC. EACH
ELEMENT OF POST IS A DRAW FROM THE POSTERIOR DISTRIBUTION
FOR EACH OF THE PARAMETERS.
ALPHA - THE CONSTANT IN THE REGRESSION.
BETA - THE SLOPE OF THE REGRESSION.
SIGSQR - THE VARIANCE OF THE INTRINSIC SCATTER.
PI - THE GAUSSIAN WEIGHTS FOR THE MIXTURE MODEL.
MU - THE GAUSSIAN MEANS FOR THE MIXTURE MODEL.
TAUSQR - THE GAUSSIAN VARIANCES FOR THE MIXTURE MODEL.
MU0 - THE HYPERPARAMETER GIVING THE MEAN VALUE OF THE
GAUSSIAN PRIOR ON MU. ONLY INCLUDED IF NGAUSS >
1.
USQR - THE HYPERPARAMETER DESCRIBING FOR THE PRIOR
VARIANCE OF THE INDIVIDUAL GAUSSIAN CENTROIDS
ABOUT MU0. ONLY INCLUDED IF NGAUSS > 1.
WSQR - THE HYPERPARAMETER DESCRIBING THE `TYPICAL' SCALE
FOR THE PRIOR ON (TAUSQR,USQR). ONLY INCLUDED IF
NGAUSS > 1.
XIMEAN - THE MEAN OF THE DISTRIBUTION FOR THE
INDEPENDENT VARIABLE, XI.
XISIG - THE STANDARD DEVIATION OF THE DISTRIBUTION FOR
THE INDEPENDENT VARIABLE, XI.
CORR - THE LINEAR CORRELATION COEFFICIENT BETWEEN THE
DEPENDENT AND INDEPENDENT VARIABLES, XI AND ETA.
CALLED ROUTINES :
RANDOMCHI, MRANDOMN, RANDOMGAM, RANDOMDIR, MULTINOM
REFERENCES :
Carroll, R.J., Roeder, K., & Wasserman, L., 1999, Flexible
Parametric Measurement Error Models, Biometrics, 55, 44
Kelly, B.C., 2007, Some Aspects of Measurement Error in
Linear Regression of Astronomical Data, The Astrophysical
Journal, 665, 1489 (arXiv:0705.2774)
Gelman, A., Carlin, J.B., Stern, H.S., & Rubin, D.B., 2004,
Bayesian Data Analysis, Chapman & Hall/CRC
REVISION HISTORY
AUTHOR : BRANDON C. KELLY, STEWARD OBS., JULY 2006
- MODIFIED PRIOR ON MU0 TO BE UNIFORM OVER [MIN(X),MAX(X)] AND
PRIOR ON USQR TO BE UNIFORM OVER [0, 1.5 * VARIANCE(X)]. THIS
TENDS TO GIVE BETTER RESULTS WITH FEWER GAUSSIANS. (B.KELLY, MAY
2007)
- FIXED BUG SO THE ITERATION COUNT RESET AFTER THE BURNIN STAGE
WHEN SILENT = 1 (B. KELLY, JUNE 2009)
- FIXED BUG WHEN UPDATING MU VIA THE METROPOLIS-HASTING
UPDATE. PREVIOUS VERSIONS DID NO INDEX MUHAT, SO ONLY MUHAT[0]
WAS USED IN THE PROPOSAL DISTRIBUTION. THANKS TO AMY BENDER FOR
POINTING THIS OUT. (B. KELLY, DEC 2011)
(See astrolib/pro/linmix_err.pro)
LINTERP
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NAME:
LINTERP
PURPOSE:
Linearly interpolate tabulated 1-d data from one grid to a new one.
EXPLANATION:
The results of LINTERP are numerically equivalent to the IDL intrinsic
INTERPOL() function, but note the following:
(1) LINTERP is a procedure rather than a function
(2) INTERPOL() extrapolates beyond the end points whereas LINTERP
truncates to the endpoints (or uses the MISSING keyword)
(3) LINTERP (unlike INTERPOL) uses the intrinsic INTERPOLATE function
and thus may have a speed advantage
(4) LINTERP always converts the new grid vector to floating point
(because INTERPOLATE does this) whereas INTERPOL() will
keep double precision if supplied.
Use QUADTERP for quadratic interpolation.
CALLING SEQUENCE:
LINTERP, Xtab, Ytab, Xint, Yint, [MISSING =, /NoInterp ]
INPUT PARAMETERS:
Xtab - Vector containing the current independent variable grid.
Must be monotonic increasing or decreasing
Ytab - Vector containing the current dependent variable values at
the XTAB grid points.
Xint - Scalar or vector containing the new independent variable grid
points for which interpolated value(s) of the dependent
variable are sought. Note that -- due to a limitation of the
intrinsic INTERPOLATE() function -- Xint is always converted to
floating point internally.
OUTPUT PARAMETERS:
Yint - Scalar or vector with the interpolated value(s) of the
dependent variable at the XINT grid points.
YINT is double precision if XTAB or YTAB are double,
otherwise YINT is REAL*4
OPTIONAL INPUT KEYWORD:
MISSING - Scalar specifying YINT value(s) to be assigned, when Xint
value(s) are outside of the range of Xtab. Default is to
truncate the out of range YINT value(s) to the nearest value
of YTAB. See the help for the INTERPOLATE function.
/NoINTERP - If supplied then LINTERP returns the YTAB value(s)
associated with the closest XTAB value(s)rather than
interpolating.
EXAMPLE:
To linearly interpolate from a spectrum wavelength-flux pair
Wave, Flux to another wavelength grid defined as:
WGrid = [1540., 1541., 1542., 1543., 1544, 1545.]
IDL> LINTERP, Wave, Flux, WGrid, FGrid
FGRID will be a 6 element vector containing the values of Flux
linearly interpolated onto the WGrid wavelength scale
PROCEDURE:
Uses TABINV to calculate the effective index of the values
in Xint in the table Xtab. The resulting index is used
with the intrinsic INTERPOLATE function to find the corresponding
Yint value in Ytab. Unless the MISSING keyword is supplied, out
of range Yint values are truncated to the nearest value of Ytab.
PROCEDURES CALLED:
TABINV, ZPARCHECK
MODIFICATION HISTORY:
Adapted from the IUE RDAF, W. Landsman October, 1988
Modified to use the new INTERPOLATE function June, 1992
Modified to always return REAL*4 October, 1992
Added MISSING keyword August, 1993
Converted to IDL V5.0 W. Landsman September 1997
Added NoInterp keyword W. Landsman July 1999
Work for unsigned, 64 bit integers W. Landsman October 2001
(See astrolib/pro/linterp.pro)
LIST_WITH_PATH
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NAME:
LIST_WITH_PATH
PURPOSE:
Search for files in a specified directory path.
EXPLANATION:
Lists files in a set of default paths, similar to using FILE_SEARCH,
except that a list of paths to be searched can be given.
CALLING SEQUENCE:
Result = LIST_WITH_PATH( FILENAME, PATHS )
INPUTS:
FILENAME = Name of file to be searched for. It may contain wildcard
characters, e.g. "*.dat".
PATHS = One or more default paths to use in the search in case
FILENAME does not contain a path itself. The individual
paths are separated by commas, although in UNIX, colons
can also be used. In other words, PATHS has the same
format as !PATH, except that commas can be used as a
separator regardless of operating system. The current
directory is always searched first, unless the keyword
NOCURRENT is set.
A leading $ can be used in any path to signal that what
follows is an environmental variable, but the $ is not
necessary. Environmental variables can themselves
contain multiple paths.
OUTPUTS:
The result of the function is a list of filenames.
EXAMPLE:
FILENAME = ''
READ, 'File to open: ', FILENAME
FILE = LIST_WITH_PATH( FILENAME, 'SERTS_DATA', '.fix' )
IF FILE NE '' THEN ...
PROCEDURE CALLS:
BREAK_PATH, CONCAT_DIR()
Category :
Utilities, Operating_system
REVISION HISTORY:
Version 1, William Thompson, GSFC, 3 November 1994
Documentation modified Wayne Landsman HSTX November 1994
Assume since V5.5, vector call to FILE_SEARCH() W. Landsman Sep 2006
Restore pre-Sep 2006 behavior of not searching subdirectories
W.Landsman. Feb 2007
(See astrolib/pro/list_with_path.pro)
LSF_ROTATE:
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NAME:
LSF_ROTATE:
PURPOSE:
Create a 1-d convolution kernel to broaden a spectrum from a rotating star
EXPLANATION:
Can be used to derive the broadening effect (line spread function; LSF)
due to rotation on a synthetic stellar spectrum. Assumes constant
limb darkening across the disk.
CALLING SEQUENCE
lsf = LSF_ROTATE(deltav, vsini, EPSILON=, VELGRID=)
INPUT PARAMETERS:
deltaV - numeric scalar giving the step increment (in km/s) in the output
rotation kernel.
Vsini - the rotational velocity projected along the line of sight (km/s)
OUTPUT PARAMETERS:
LSF - The convolution kernel vector for the specified rotational velocity.
The number of points in LSF will be always be odd (the kernel is
symmetric) and equal to either ceil(2*Vsini/deltav) or
ceil(2*Vsini/deltav) +1 (whichever number is odd). LSF will
always be of type FLOAT.
To actually compute the broadening. the spectrum should be convolved
with the rotational LSF.
OPTIONAL INPUT PARAMETERS:
Epsilon - numeric scalar giving the limb-darkening coefficient,
default = 0.6 which is typical for photospheric lines. The
specific intensity I at any angle theta from the specific intensity
Icen at the center of the disk is given by:
I = Icen*(1-epsilon*(1-cos(theta))
OPTIONAL OUTPUT PARAMETER:
Velgrid - Vector with the same number of elements as LSF
EXAMPLE:
(1) Plot the LSF for a star rotating at 90 km/s in both velocity space and
for a central wavelength of 4300 A. Compute the LSF every 3 km/s
IDL> lsf = lsf_rotate(3,90,velgrid=vel) ;LSF will contain 61 pts
IDL> plot,vel,lsf ;Plot the LSF in velocity space
IDL> wgrid = 4300*(1+vel/3e5) ;Speed of light = 3e5 km/s
IDL> oplot,wgrid,lsf ;Plot in wavelength space
NOTES:
Adapted from rotin3.f in the SYNSPEC software of Hubeny & Lanz
.http://nova.astro.umd.edu/index.html Also see Eq. 17.12 in
"The Observation and Analysis of Stellar Photospheres" by D. Gray (1992)
REVISION HISTORY:
Written, W. Landsman November 2001
(See astrolib/pro/lsf_rotate.pro)
LUMDIST
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NAME:
LUMDIST
PURPOSE:
Calculate luminosity distance (in Mpc) of an object given its redshift
EXPLANATION:
The luminosity distance in the Friedmann-Robertson-Walker model is
taken from Caroll, Press, and Turner (1992, ARAA, 30, 499), p. 511
Uses a closed form (Mattig equation) to compute the distance when the
cosmological constant is zero. Otherwise integrates the function using
QSIMP.
CALLING SEQUENCE:
result = lumdist(z, [H0 = , k = , Omega_M =, Lambda0 = , q0 = ,/SILENT])
INPUTS:
z = redshift, positive scalar or vector
OPTIONAL KEYWORD INPUTS:
/SILENT - If set, the program will not display adopted cosmological
parameters at the terminal.
H0: Hubble parameter in km/s/Mpc, default is 70
No more than two of the following four parameters should be
specified. None of them need be specified -- the adopted defaults
are given.
k - curvature constant, normalized to the closure density. Default is
0, indicating a flat universe
Omega_m - Matter density, normalized to the closure density, default
is 0.3. Must be non-negative
Lambda0 - Cosmological constant, normalized to the closure density,
default is 0.7
q0 - Deceleration parameter, numeric scalar = -R*(R'')/(R')^2, default
is -0.55
OUTPUTS:
The result of the function is the luminosity distance (in Mpc) for each
input value of z.
EXAMPLE:
(1) Plot the distance of a galaxy in Mpc as a function of redshift out
to z = 5.0, assuming the default cosmology (Omega_m=0.3, Lambda = 0.7,
H0 = 70 km/s/Mpc)
IDL> z = findgen(50)/10.
IDL> plot,z,lumdist(z),xtit='z',ytit='Distance (Mpc)'
Now overplot the relation for zero cosmological constant and
Omega_m=0.3
IDL> oplot,z,lumdist(z,lambda=0,omega=0.3),linestyle=1
COMMENTS:
(1) Integrates using the IDL Astronomy Version procedure QSIMP. (The
intrinsic IDL QSIMP function is not called because of its ridiculous
restriction that only scalar arguments can be passed to the integrating
function.)
(2) Can fail to converge at high redshift for closed universes with
non-zero lambda. This can presumably be fixed by replacing QSIMP with
an integrator that can handle a singularity
PROCEDURES CALLED:
COSMO_PARAM, QSIMP
REVISION HISTORY:
Written W. Landsman Raytheon ITSS April 2000
Avoid integer overflow for more than 32767 redshifts July 2001
Use double precision J. Moustakas/W. Landsman April 2008
(See astrolib/pro/lumdist.pro)
MAG2FLUX
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NAME:
MAG2FLUX
PURPOSE:
Convert from magnitudes to flux (ergs/s/cm^2/A).
EXPLANATION:
Use FLUX2MAG() for the opposite direction.
CALLING SEQUENCE:
flux = mag2flux( mag, [ zero_pt, ABwave = ] )
INPUTS:
mag - scalar or vector of magnitudes
OPTIONAL INPUT:
zero_pt - scalar giving the zero point level of the magnitude.
If not supplied then zero_pt = 21.1 (Code et al. 1976)
Ignored if the ABwave keyword is set.
OPTIONAL KEYWORD INPUT:
ABwave - wavelength scalar or vector in Angstroms. If supplied, then
the input vector, mag, is assumed to contain Oke AB magnitudes
(Oke & Gunn 1983, ApJ, 266, 713)
OUTPUT:
flux - scalar or vector flux vector, in erg cm-2 s-1 A-1
If the ABwave keyword is set, then the flux is given by
f = 10^(-0.4*(mag +2.406 + 4*alog10(ABwave)))
Otherwise the flux is given by
f = 10^(-0.4*(mag + zero_pt))
EXAMPLE:
Suppose one is given vectors of wavelengths and AB magnitudes, w (in
Angstroms) and mag. Plot the spectrum in erg cm-2 s-1 A-1
IDL> plot, w, mag2flux(mag,ABwave = w)
REVISION HISTORY:
Written J. Hill STX Co. 1988
Converted to IDL V5.0 W. Landsman September 1997
Added ABwave keyword, W. Landsman September 1998
(See astrolib/pro/mag2flux.pro)
MAG2GEO()
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NAME:
MAG2GEO()
PURPOSE:
Convert from geomagnetic to geographic coordinates
EXPLANATION:
Converts from GEOMAGNETIC (latitude,longitude) to GEOGRAPHIC (latitude,
longitude). (altitude remains the same)
CALLING SEQUENCE:
gcoord=mag2geo(mcoord)
INPUT:
mcoord = a 2-element array of magnetic [latitude,longitude], or an
array [2,n] of n such coordinates.
KEYWORD INPUTS:
None
OUTPUT:
a 2-element array of geographic [latitude,longitude], or an array [2,n]
of n such coordinates
COMMON BLOCKS:
None
EXAMPLES:
IDL> gcoord=mag2geo([90,0]) ; coordinates of magnetic south pole
IDL> print,gcoord
79.300000 -71.409990
MODIFICATION HISTORY:
Written by Pascal Saint-Hilaire ([email protected]),
May 2002
(See astrolib/pro/mag2geo.pro)
MAKE_2D
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NAME:
MAKE_2D
PURPOSE:
Change from 1-d indexing to 2-d indexing
EXPLANATION:
Convert an N element X vector, and an M element Y vector, into
N x M arrays giving all possible combination of X and Y pairs.
Useful for obtaining the X and Y positions of each element of
a regular grid.
CALLING SEQUENCE:
MAKE_2D, X, Y, [ XX, YY ]
INPUTS:
X - N element vector of X positions
Y - M element vector of Y positions
OUTPUTS:
XX - N x M element array giving the X position at each pixel
YY - N x M element array giving the Y position of each pixel
If only 2 parameters are supplied then X and Y will be
updated to contain the output arrays
EXAMPLE:
To obtain the X and Y position of each element of a 30 x 15 array
IDL> x = indgen(30) & y = indgen(15)
IDL> make_2d, x, y
REVISION HISTORY:
Written, Wayne Landsman ST Systems Co. May, 1988
Added /NOZERO keyword W. Landsman Mar, 1991
Converted to IDL V5.0 W. Landsman September 1997
Improved speed P. Broos July 2000
(See astrolib/pro/make_2d.pro)
MAKE_ASTR
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NAME:
MAKE_ASTR
PURPOSE:
Build an astrometry structure from input parameter values
EXPLANATION:
This structure can be subsequently placed in a FITS header with
PUTAST
CALLING SEQUENCE:
MAKE_ASTR, astr, CD = , DELT =, CRPIX =, CRVAL =, CTYPE =,
LATPOLE = , LONGPOLE =, PV2_1 = PV2_2 = , PV2_3 =
OUTPUT PARAMETER:
ASTR - Anonymous structure containing astrometry info. See the
documentation for EXTAST for descriptions of the individual
tags
REQUIRED INPUT KEYWORDS
CRPIX - 2 element vector giving X and Y coordinates of reference pixel
(def = NAXIS/2). VALUES MUST BE IN FITS CONVENTION (first pixel
is [1,1]) AND NOT IDL CONVENTION (first pixel is [0,0]).
CRVAL - 2 element double precision vector giving R.A. and DEC of
reference pixel in DEGREES
OPTIONAL INPUT KEYWORDS
CD - 2 x 2 array containing the astrometry parameters CD1_1 CD1_2
in DEGREES/PIXEL CD2_1 CD2_2
DELT - 2 element vector giving physical increment at reference pixel
in DEGREES/PIXEL default = [-1.0D, 1.0D]/3600. (1 arcsec/pixel)
CTYPE - 2 element string vector giving projection types, default
['RA---TAN','DEC--TAN']
LATPOLE - Scalar latitude of the north pole, default = 0
LONGPOLE - scalar longitude of north pole, default = 180
Note that the default value of 180 is valid only for zenithal
projections; it should be set to PV2_1 for conic projections,
and zero for other projections.
PV2 - Vector of projection parameters. Not required for some
projections (e.g. TAN) and optional for others (e.g. SIN).
Usually a 2 element vector, but may contain up to 21 elements
for the Zenithal Polynomial (ZPN) projection. Corresponds to
the keywords PV2_1, PV2_2... Defaults to 0.0
NOTES:
(1) An anonymous structure is created to avoid structure definition
conflicts. This is needed because some projection systems
require additional dimensions (i.e. spherical cube
projections require a specification of the cube face).
(2) The name of the keyword for the CDELT parameter is DELT because
the IDL keyword CDELT would conflict with the CD keyword
(3) The astrometry structure definition was slightly modified in
July 2003; all angles are now double precision, and the
LATPOLE tag was added. In April 2007 the CRPIX tag was also
changed to double precision.
REVISION HISTORY:
Written by W. Landsman Mar. 1994
Added LATPOLE, all angles double precision W. Landsman July 2003
Use PV2 keyword rather than PROJP1, PROJP2 W. Landsman May 2004
Make .CRPIX tag double precision, change CDELT default to 1"/pixel
W. Landsman April 2007
Default plate scale is now 1"/pixel (not 1 deg/pix) WL Oct. 2010
Oct 2010 change should only apply when CD matrix not given
M. Cushing/W.L. Aug 2011
(See astrolib/pro/make_astr.pro)
MATCH
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NAME:
MATCH
PURPOSE:
Routine to match values in two vectors.
CALLING SEQUENCE:
match, a, b, suba, subb, [ COUNT =, /SORT, EPSILON = ]
INPUTS:
a,b - two vectors to match elements, numeric or string data types
OUTPUTS:
suba - subscripts of elements in vector a with a match
in vector b
subb - subscripts of the positions of the elements in
vector b with matchs in vector a.
suba and subb are ordered such that a[suba] equals b[subb]
OPTIONAL INPUT KEYWORD:
/SORT - By default, MATCH uses two different algorithm: (1) the
/REVERSE_INDICES keyword to HISTOGRAM is used for integer data,
while (2) a sorting algorithm is used for non-integer data. The
histogram algorithm is usually faster, except when the input
vectors are sparse and contain very large numbers, possibly
causing memory problems. Use the /SORT keyword to always use
the sort algorithm.
epsilon - if values are within epsilon, they are considered equal. Used only
only for non-integer matching. Note that input vectors should
be unique to within epsilon to provide one-to-one mapping..
Default=0.
OPTIONAL KEYWORD OUTPUT:
COUNT - set to the number of matches, integer scalar
SIDE EFFECTS:
The obsolete system variable !ERR is set to the number of matches;
however, the use !ERR is deprecated in favor of the COUNT keyword
RESTRICTIONS:
The vectors a and b should not have duplicate values within them.
You can use rem_dup function to remove duplicate values
in a vector
EXAMPLE:
If a = [3,5,7,9,11] & b = [5,6,7,8,9,10]
then
IDL> match, a, b, suba, subb, COUNT = count
will give suba = [1,2,3], subb = [0,2,4], COUNT = 3
and a[suba] = b[subb] = [5,7,9]
METHOD:
For non-integer data types, the two input vectors are combined and
sorted and the consecutive equal elements are identified. For integer
data types, the /REVERSE_INDICES keyword to HISTOGRAM of each array
is used to identify where the two arrays have elements in common.
HISTORY:
D. Lindler Mar. 1986.
Fixed "indgen" call for very large arrays W. Landsman Sep 1991
Added COUNT keyword W. Landsman Sep. 1992
Fixed case where single element array supplied W. Landsman Aug 95
Use a HISTOGRAM algorithm for integer vector inputs for improved
performance W. Landsman March 2000
Work again for strings W. Landsman April 2000
Use size(/type) W. Landsman December 2002
Work for scalar integer input W. Landsman June 2003
Assume since V5.4, use COMPLEMENT to WHERE() W. Landsman Apr 2006
Added epsilon keyword Kim Tolbert March 14, 2008
(See astrolib/pro/match.pro)
MATCH2
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NAME:
MATCH2
PURPOSE:
Routine to cross-match values in two vectors (including non-matches)
EXPLANATION:
This procedure *appears* similar to MATCH of the IDL astronomy
library. However, this routine is quite different in that it
reports an index value for each element of the input arrays.
In other words, while MATCH reports the *existence* of
matching elements in each array, MATCH2 reports explicitly
*which* elements match.
Furthermore, while MATCH reports only unique matching
elements, MATCH2 will always report a cross-match for every
element in each array, even if it is a repeat.
In cases where no match was found, an index of -1 is
reported.
CALLING SEQUENCE:
match2, a, b, suba, subb
INPUTS:
a,b - two vectors to match elements, numeric or string data types
OUTPUTS:
suba - vector with same number of elements as A, such that
A EQ B[SUBA], except non-matches which are indicated
by SUBA EQ -1
subb - vector with same number of elements as B, such that
B EQ A[SUBB], except non-matches which are indicated
by SUBB EQ -1
RESTRICTIONS:
The vectors A and B are allowed to have duplicates in them,
but for matching purposes, only the first one found will
be reported.
EXAMPLE:
A = [0,7,14,23,24,30]
B = [7,8,14,25,14]
IDL> match2, a, b, suba, subb
--> suba = [ -1 , 0, 4, -1, -1, -1 ]
(indicates that A[1] matches B[1] and A[3] matches B[2])
--> subb = [ 1 , -1, 2, -1, 2 ]
(indicates that B[1] matches A[1] and B[2] matches A[3])
Compare to the results of the original MATCH procedure,
IDL> match, a, b, suba, subb
--> suba = [ 1, 3]
(indicates that A[1] and A[3] match elements in B, but not which ones)
--> subb = [ 1, 2]
(indicates that B[1] and B[2] match elements in A, but not which ones)
MODIFICATION HISTORY
Derived from the IDL Astronomy Library MATCH, 14 Feb 2007
Updated documentation, 17 Jul 2007
More updated documentation (example), 03 Sep 2007
(See astrolib/pro/match2.pro)
MAX_ENTROPY
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NAME:
MAX_ENTROPY
PURPOSE:
Deconvolution of data by Maximum Entropy analysis, given the PSF
EXPLANATION:
Deconvolution of data by Maximum Entropy analysis, given the
instrument point spread response function (spatially invariant psf).
Data can be an observed image or spectrum, result is always positive.
Default is convolutions using FFT (faster when image size = power of 2).
CALLING SEQUENCE:
for i=1,Niter do begin
Max_Entropy, image_data, psf, image_deconv, multipliers, FT_PSF=psf_ft
INPUTS:
data = observed image or spectrum, should be mostly positive,
with mean sky (background) near zero.
psf = Point Spread Function of instrument (response to point source,
must sum to unity).
deconv = result of previous call to Max_Entropy,
multipliers = the Lagrange multipliers of max.entropy theory
(on first call, set = 0, giving flat first result).
OUTPUTS:
deconv = deconvolution result of one more iteration by Max_Entropy.
multipliers = the Lagrange multipliers saved for next iteration.
OPTIONAL INPUT KEYWORDS:
FT_PSF = passes (out/in) the Fourier transform of the PSF,
so that it can be reused for the next time procedure is called,
/NO_FT overrides the use of FFT, using the IDL function convol() instead.
/LINEAR switches to Linear convergence mode, much slower than the
default Logarithmic convergence mode.
LOGMIN = minimum value constraint for taking Logarithms (default=1.e-9).
EXTERNAL CALLS:
function convolve( image, psf ) for convolutions using FFT or otherwise.
METHOD:
Iteration with PSF to maximize entropy of solution image with
constraint that the solution convolved with PSF fits data image.
Based on paper by Hollis, Dorband, Yusef-Zadeh, Ap.J. Feb.1992,
which refers to Agmon, Alhassid, Levine, J.Comp.Phys. 1979.
A more elaborate image deconvolution program using maximum entropy is
available at
http://sohowww.nascom.nasa.gov/solarsoft/gen/idl/image/image_deconvolve.pro
HISTORY:
written by Frank Varosi at NASA/GSFC, 1992.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/max_entropy.pro)
MAX_LIKELIHOOD
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NAME:
MAX_LIKELIHOOD
PURPOSE:
Maximum likelihood deconvolution of an image or a spectrum.
EXPLANATION:
Deconvolution of an observed image (or spectrum) given the
instrument point spread response function (spatially invariant psf).
Performs iteration based on the Maximum Likelihood solution for
the restoration of a blurred image (or spectrum) with additive noise.
Maximum Likelihood formulation can assume Poisson noise statistics
or Gaussian additive noise, yielding two types of iteration.
CALLING SEQUENCE:
for i=1,Niter do Max_Likelihood, data, psf, deconv, FT_PSF=psf_ft
INPUTS PARAMETERS:
data = observed image or spectrum, should be mostly positive,
with mean sky (background) near zero.
psf = Point Spread Function of the observing instrument,
(response to a point source, must sum to unity).
INPUT/OUTPUT PARAMETERS:
deconv = as input: the result of previous call to Max_Likelihood,
(initial guess on first call, default = average of data),
as output: result of one more iteration by Max_Likelihood.
Re_conv = (optional) the current deconv image reconvolved with PSF
for use in next iteration and to check convergence.
OPTIONAL INPUT KEYWORDS:
/GAUSSIAN causes max-likelihood iteration for Gaussian additive noise
to be used, otherwise the default is Poisson statistics.
FT_PSF = passes (out/in) the Fourier transform of the PSF,
so that it can be reused for the next time procedure is called,
/NO_FT overrides the use of FFT, using the IDL function convol() instead.
POSITIVITY_EPS = value of epsilon passed to function positivity,
default = -1 which means no action (identity).
UNDERFLOW_ZERO = cutoff to consider as zero, if numbers less than this.
EXTERNAL CALLS:
function convolve( image, psf ) for convolutions using FFT or otherwise.
function positivity( image, EPS= ) to make image positive.
METHOD:
Maximum Likelihood solution is a fixed point of an iterative eq.
(derived by setting partial derivatives of Log(Likelihood) to zero).
Poisson noise case was derived by Richardson(1972) & Lucy(1974).
Gaussian noise case is similar with subtraction instead of division.
NOTES:
WARNING: The Poisson case may not conserve flux for an odd image size.
This behavior is being investigated.
HISTORY:
written: Frank Varosi at NASA/GSFC, 1992.
F.V. 1993, added optional arg. Re_conv (to avoid doing it twice).
Converted to IDL V5.0 W. Landsman September 1997
Use COMPLEMENT keyword to WHERE() W. Landsman Jan 2008
(See astrolib/pro/max_likelihood.pro)
MEANCLIP
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NAME:
MEANCLIP
PURPOSE:
Computes an iteratively sigma-clipped mean on a data set
EXPLANATION:
Clipping is done about median, but mean is returned.
Called by SKYADJ_CUBE
CATEGORY:
Statistics
CALLING SEQUENCE:
MEANCLIP, Data, Mean, [ Sigma, SUBS =
CLIPSIG=, MAXITER=, CONVERGE_NUM=, /VERBOSE, /DOUBLE ]
INPUT POSITIONAL PARAMETERS:
Data: Input data, any numeric array
OUTPUT POSITIONAL PARAMETERS:
Mean: N-sigma clipped mean.
Sigma: Standard deviation of remaining pixels.
INPUT KEYWORD PARAMETERS:
CLIPSIG: Number of sigma at which to clip. Default=3
MAXITER: Ceiling on number of clipping iterations. Default=5
CONVERGE_NUM: If the proportion of rejected pixels is less
than this fraction, the iterations stop. Default=0.02, i.e.,
iteration stops if fewer than 2% of pixels excluded.
/VERBOSE: Set this flag to get messages.
/DOUBLE - if set then perform all computations in double precision.
Otherwise double precision is used only if the input
data is double
OUTPUT KEYWORD PARAMETER:
SUBS: Subscript array for pixels finally used.
MODIFICATION HISTORY:
Written by: RSH, RITSS, 21 Oct 98
20 Jan 99 - Added SUBS, fixed misplaced paren on float call,
improved doc. RSH
Nov 2005 Added /DOUBLE keyword, check if all pixels are removed
by clipping W. Landsman
(See astrolib/pro/meanclip.pro)
MEDARR
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NAME:
MEDARR
PURPOSE:
Compute the median at each pixel across a set of 2-d images
EXPLANATION:
Each pixel in the output array contains the median of the
corresponding pixels in the input arrays. Useful, for example to
combine a stack of CCD images, while removing cosmic ray hits.
This routine became partially obsolete in V5.6 with the introduction
of the DIMENSION keyword to the intrinsic MEDIAN() function. However,
it is still useful if a input mask is needed (though it is much
faster to set invalid pixels to NaN values.)
CALLING SEQUENCE:
MEDARR, inarr, outarr, [ mask, output_mask ]
INPUTS:
inarr -- A three dimensional array containing the input arrays to
combine together. Each of the input arrays must be two
dimensional and must have the same dimensions. These arrays
should then be stacked together into a single 3-D array,
creating INARR.
OPTIONAL INPUT:
mask -- Same structure as inarr, byte array with 1b where
pixels are to be included, 0b where they are to be
excluded. For floating point images, it is much faster to
set masked pixels in inarr equal to !VALUES.F_NAN (see below),
rather than use the mask parameter.
OUTPUTS:
outarr -- The output array. It will have dimensions equal to the
first two dimensions of the input array.
OPTIONAL OUPUT:
output_mask -- Same structure as outarr, byte array with 1b
pixels are valid, 0b where all the input pixels
have been masked out.
RESTRICTIONS:
This procedure was *SLOW* when using the Mask parameter because it has
to loop over each pixel of the image.
EXAMPLE:
Suppose one wants to combine three floating point 1024 x 1024 bias
frames which have been read into the IDL variables im1,im2,im3
IDL> bigim = fltarr(1024,1024,3) ;Create big array to hold images
IDL> bigim(0,0,0) = im1 & bigim(0,0,1) = im2 & bigim(0,0,2) = im2
IDL> medarr, bigim, avgbias
The variable avgbias will be the desired 1024x 1024 float image.
PROCEDURE:
If the MASK parameter is not set, then MEDARR is just a wrapper for
MEDIAN(/EVEN, dimension = 3). If the MASK parameter is set,
a scalar median function over the third dimension is looped over
each pixel of the first two dimensions. The /EVEN keyword is used
with MEDIAN (which averages the two middle values), since this avoids
biasing the output for an even number of images.
Any values set to NAN (not a number) are ignored when computing the
median. If all values for a pixel location are NAN, then the median
is also returned as NAN.
MODIFICATION HISTORY:
Written by Michael R. Greason, STX, 12 June 1990.
Don't use MEDIAN function for even number of images.
W. Landsman Sep 1996
Mask added. RS Hill, HSTX, 13 Mar. 1997
Converted to IDL V5.0 W. Landsman September 1997
Use /EVEN keyword to MEDIAN W. Landsman September 1997
Rearranged code for faster execution W. Landsman January 1998
Faster execution for odd number of images W. Landsman July 2000
V5.4 fix for change in SIZE() definition of undefined variable
W. Landsman/E. Young May 2001
Use MEDIAN(/DIMEN) for V5.6 or later W. Landsman November 2002
Use keyword_set() instead of ARG_present() to test for presence of mask
parameter D. Hanish/W. Landsman June 2003
Assume since V5.6 W. Landsman Feb 2004
(See astrolib/pro/medarr.pro)
MEDSMOOTH
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NAME:
MEDSMOOTH
PURPOSE:
Median smoothing of a vector, including points near its ends.
CALLING SEQUENCE:
SMOOTHED = MEDSMOOTH( VECTOR, WINDOW_WIDTH )
INPUTS:
VECTOR = The (1-d numeric) vector to be smoothed
WINDOW = Odd integer giving the full width of the window over which
the median is determined for each point. (If WINDOW is
specified as an even number, then the effect is the same as
using WINDOW+1)
OUTPUT:
Function returns the smoothed vector
PROCEDURE:
Each point is replaced by the median of the nearest WINDOW of points.
The width of the window shrinks towards the ends of the vector, so that
only the first and last points are not filtered. These points are
replaced by forecasting from smoothed interior points.
EXAMPLE:
Create a vector with isolated high points near its ends
IDL> a = randomn(seed,40) & a[1] = 10 & a[38] = 10
Now do median smoothing with a 7 point window
IDL> b = medsmooth(a,7)
Note that, unlike MEDIAN(), that MEDSMOOTH will remove the isolated
high points near the ends.
REVISION HISTORY:
Written, H. Freudenreich, STX, 12/89
H.Freudenreich, 8/90: took care of end-points by shrinking window.
Speed up using vector median when possible W. Landsman February 2002
(See astrolib/pro/medsmooth.pro)
MINF_BRACKET
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NAME:
MINF_BRACKET
PURPOSE:
Bracket a local minimum of a 1-D function with 3 points,
EXPLANATION:
Brackets a local minimum of a 1-d function with 3 points,
thus ensuring that a minimum exists somewhere in the interval.
This routine assumes that the function has a minimum somewhere....
Routine can also be applied to a scalar function of many variables,
for such case the local minimum in a specified direction is bracketed,
This routine is called by minF_conj_grad, to bracket minimum in the
direction of the conjugate gradient of function of many variables
CALLING EXAMPLE:
xa=0 & xb=1
minF_bracket, xa,xb,xc, fa,fb,fc, FUNC_NAME="name" ;for 1-D func.
or:
minF_bracket, xa,xb,xc, fa,fb,fc, FUNC="name", $
POINT=[0,1,1], $
DIRECTION=[2,1,1] ;for 3-D func.
INPUTS:
xa = scalar, guess for point bracketing location of minimum.
xb = scalar, second guess for point bracketing location of minimum.
KEYWORDS:
FUNC_NAME = function name (string)
Calling mechanism should be: F = func_name( px )
where:
px = scalar or vector of independent variables, input.
F = scalar value of function at px.
POINT_NDIM = when working with function of N variables,
use this keyword to specify the starting point in N-dim space.
Default = 0, which assumes function is 1-D.
DIRECTION = when working with function of N variables,
use this keyword to specify the direction in N-dim space
along which to bracket the local minimum, (default=1 for 1-D).
(xa,xb,xc) are then relative distances from POINT_NDIM.
OUTPUTS:
xa,xb,xc = scalars, 3 points which bracket location of minimum,
that is, f(xb) < f(xa) and f(xb) < f(xc), so minimum exists.
When working with function of N variables
(xa,xb,xc) are then relative distances from POINT_NDIM,
in the direction specified by keyword DIRECTION,
with scale factor given by magnitude of DIRECTION.
OPTIONAL OUTPUT:
fa,fb,fc = value of function at 3 points which bracket the minimum,
again note that fb < fa and fb < fc if minimum exists.
PROCEDURE:
algorithm from Numerical Recipes (by Press, et al.), sec.10.1 (p.281).
MODIFICATION HISTORY:
Written, Frank Varosi NASA/GSFC 1992.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/minf_bracket.pro)
MINF_CONJ_GRAD
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NAME:
MINF_CONJ_GRAD
PURPOSE:
Find the local minimum of a scalar function using conjugate gradient
EXPLANATION:
Find the local minimum of a scalar function of several variables using
the Conjugate Gradient method (Fletcher-Reeves-Polak-Ribiere algorithm).
Function may be anything with computable partial derivatives.
Each call to minF_conj_grad performs one iteration of algorithm,
and returns an N-dim point closer to the local minimum of function.
CALLING EXAMPLE:
p_min = replicate( 1, N_dim )
minF_conj_grad, p_min, f_min, conv_factor, FUNC_NAME="name",/INITIALIZE
while (conv_factor GT 0) do begin
minF_conj_grad, p_min, f_min, conv_factor, FUNC_NAME="name"
endwhile
INPUTS:
p_min = vector of independent variables, location of minimum point
obtained from previous call to minF_conj_grad, (or first guess).
KEYWORDS:
FUNC_NAME = function name (string)
Calling mechanism should be: F = func_name( px, gradient )
where:
F = scalar value of function at px.
px = vector of independent variables, input.
gradient = vector of partial derivatives of the function
with respect to independent variables, evaluated at px.
This is an optional output parameter:
gradient should not be calculated if parameter is not
supplied in call (Unless you want to waste some time).
/INIT must be specified on first call (whenever p_min is a guess),
to initialize the iteration scheme of algorithm.
/USE_DERIV causes the directional derivative of function to be used
in the 1-D minimization part of algorithm
(default is not to use directional derivative).
TOLERANCE = desired accuracy of minimum location, default=sqrt(1.e-7).
/QUADRATIC runs simpler version which works only for quadratic function.
OUTPUTS:
p_min = vector giving improved solution for location of minimum point.
f_min = value of function at p_min.
conv_factor = gives the current rate of convergence (change in value),
iteration should be stopped when rate gets near zero.
EXTERNAL CALLS:
pro minF_bracket, to find 3 points which bracket the minimum in 1-D.
pro minF_parabolic, to find minimum point in 1-D.
pro minF_parabol_D, to find minimum point in 1-D, using derivatives.
COMMON BLOCKS:
common minf_conj_grad, grad_conj, grad_save, gs_norm
(to keep conjugate gradient, gradient and norm from previous iteration)
PROCEDURE:
Algorithm adapted from Numerical Recipes, sec.10.6 (p.305).
Conjugate gradient is computed from gradient, which then gives
the best direction (in N-dim space) in which to proceed to find
the minimum point. The function is then minimized along
this direction of conjugate gradient (a 1-D minimization).
The algorithm is repeated starting at the new point by calling again.
MODIFICATION HISTORY:
Written, Frank Varosi NASA/GSFC 1992.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/minf_conj_grad.pro)
MINF_PARABOLIC
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NAME:
MINF_PARABOLIC
PURPOSE:
Minimize a function using Brent's method with parabolic interpolation
EXPLANATION:
Find a local minimum of a 1-D function up to specified tolerance.
This routine assumes that the function has a minimum nearby.
(recommend first calling minF_bracket, xa,xb,xc, to bracket minimum).
Routine can also be applied to a scalar function of many variables,
for such case the local minimum in a specified direction is found,
This routine is called by minF_conj_grad, to locate minimum in the
direction of the conjugate gradient of function of many variables.
CALLING EXAMPLES:
minF_parabolic, xa,xb,xc, xmin, fmin, FUNC_NAME="name" ;for 1-D func.
or:
minF_parabolic, xa,xb,xc, xmin, fmin, FUNC="name", $
POINT=[0,1,1], $
DIRECTION=[2,1,1] ;for 3-D func.
INPUTS:
xa,xb,xc = scalars, 3 points which bracket location of minimum,
that is, f(xb) < f(xa) and f(xb) < f(xc), so minimum exists.
When working with function of N variables
(xa,xb,xc) are then relative distances from POINT_NDIM,
in the direction specified by keyword DIRECTION,
with scale factor given by magnitude of DIRECTION.
INPUT KEYWORDS:
FUNC_NAME = function name (string)
Calling mechanism should be: F = func_name( px )
where:
px = scalar or vector of independent variables, input.
F = scalar value of function at px.
POINT_NDIM = when working with function of N variables,
use this keyword to specify the starting point in N-dim space.
Default = 0, which assumes function is 1-D.
DIRECTION = when working with function of N variables,
use this keyword to specify the direction in N-dim space
along which to bracket the local minimum, (default=1 for 1-D).
(xa, xb, xc, x_min are then relative distances from POINT_NDIM)
MAX_ITER = maximum allowed number iterations, default=100.
TOLERANCE = desired accuracy of minimum location, default=sqrt(1.e-7).
OUTPUTS:
xmin = estimated location of minimum.
When working with function of N variables,
xmin is the relative distance from POINT_NDIM,
in the direction specified by keyword DIRECTION,
with scale factor given by magnitude of DIRECTION,
so that min. Loc. Pmin = Point_Ndim + xmin * Direction.
fmin = value of function at xmin (or Pmin).
PROCEDURE:
Brent's method to minimize a function by using parabolic interpolation.
Based on function BRENT in Numerical Recipes in FORTRAN (Press et al.
1992), sec.10.2 (p. 397).
MODIFICATION HISTORY:
Written, Frank Varosi NASA/GSFC 1992.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/minf_parabolic.pro)
MINF_PARABOL_D
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NAME:
MINF_PARABOL_D
PURPOSE:
Minimize a function using a modified Brent's method with derivatives
EXPLANATION:
Based on the procedure DBRENT in Numerical Recipes by Press et al.
Finds a local minimum of a 1-D function up to specified tolerance,
using the first derivative of function in the algorithm.
This routine assumes that the function has a minimum nearby.
(recommend first calling minF_bracket, xa,xb,xc, to bracket minimum).
Routine can also be applied to a scalar function of many variables,
for such case the local minimum in a specified direction is found,
This routine is called by minF_conj_grad, to locate minimum in the
direction of the conjugate gradient of function of many variables.
CALLING EXAMPLES:
minF_parabol_D, xa,xb,xc, xmin, fmin, FUNC_NAME="name" ;for 1-D func.
or:
minF_parabol_D, xa,xb,xc, xmin, fmin, FUNC="name", $
POINT=[0,1,1], $
DIRECTION=[2,1,1] ;for 3-D func.
INPUTS:
xa,xb,xc = scalars, 3 points which bracket location of minimum,
that is, f(xb) < f(xa) and f(xb) < f(xc), so minimum exists.
When working with function of N variables
(xa,xb,xc) are then relative distances from POINT_NDIM,
in the direction specified by keyword DIRECTION,
with scale factor given by magnitude of DIRECTION.
KEYWORDS:
FUNC_NAME = function name (string)
Calling mechanism should be: F = func_name( px, gradient )
where:
px = scalar or vector of independent variables, input.
F = scalar value of function at px.
gradient = derivative of function, a scalar if 1-D,
a gradient vector if N-D,
(should only be computed if arg. is present).
POINT_NDIM = when working with function of N variables,
use this keyword to specify the starting point in N-dim space.
Default = 0, which assumes function is 1-D.
DIRECTION = when working with function of N variables,
use this keyword to specify the direction in N-dim space
along which to bracket the local minimum, (default=1 for 1-D).
(xa, xb, xc, x_min are then relative distances from POINT_NDIM)
MAX_ITER = maximum allowed number iterations, default=100.
TOLERANCE = desired accuracy of minimum location, default=sqrt(1.e-7).
OUTPUTS:
xmin = estimated location of minimum.
When working with function of N variables,
xmin is the relative distance from POINT_NDIM,
in the direction specified by keyword DIRECTION,
with scale factor given by magnitude of DIRECTION,
so that min. Loc. Pmin = Point_Ndim + xmin * Direction.
fmin = value of function at xmin (or Pmin).
PROCEDURE:
Brent's method to minimize a function by using parabolic interpolation
and using first derivative of function,
from Numerical Recipes (by Press, et al.), sec.10.3 (p.287),
MODIFICATION HISTORY:
Written, Frank Varosi NASA/GSFC 1992.
(See astrolib/pro/minf_parabol_d.pro)
MINMAX
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NAME:
MINMAX
PURPOSE:
Return a 2 element array giving the minimum and maximum of an array
EXPLANATION:
Using MINMAX() is faster than doing a separate MAX and MIN.
The procedure MAXMIN in http://www.idlcoyote.com/programs/maxmin.pro
has a similar purpose but uses a procedure call rather than a function.
CALLING SEQUENCE:
value = minmax( array, [subs, /NAN, DIMEN= ] )
INPUTS:
array - an IDL numeric scalar, vector or array.
OUTPUTS:
value = a two element vector (if DIMEN is not supplied)
value[0] = minimum value of array
value[1] = maximum value of array
If the DIMEN keyword is supplied then value will be a 2 x N element
array where N is the number of elements in the specified
dimension
OPTIONAL OUTPUT PARAMETER:
subs - two-dimensional vector; the first element gives the subscript
of the minimum value, the second element gives the subscript
of the maximum value.
OPTIONAL INPUT KEYWORD:
/NAN - Set this keyword to cause the routine to check for occurrences
of the IEEE floating-point value NaN in the input data. Elements
with the value NaN are treated as missing data.
DIMEN - integer (either 1 or 2) specifying which dimension of a 2-d
array to take the minimum and maximum. Note that (unlike the
DIMENSION keyword to the MIN() function) DIMEN is only valid
for a 2-d array, larger dimensions are not supported.
EXAMPLE:
(1) Print the minimum and maximum of an image array, im
IDL> print, minmax( im )
(2) Given a 2-dimension array of (echelle) wavelengths w, print the
minimum and maximum of each order
print,minmax(w,dimen=1)
PROCEDURE:
The MIN function is used with the MAX keyword
REVISION HISTORY:
Written W. Landsman January, 1990
Added NaN keyword. M. Buie June 1998
Added DIMEN keyword W. Landsman January 2002
Added SUBSCRIPT_MIN and SUBSCRIPT_MAX BT Jan 2005
Added optional subs output parameter W. Landsman July 2009
(See astrolib/pro/minmax.pro)
MKHDR
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NAME:
MKHDR
PURPOSE:
Make a minimal primary (or IMAGE extension) FITS header
EXPLANATION:
If an array is supplied, then the created FITS header will be
appropriate to the supplied array. Otherwise, the user can specify
the dimensions and datatype.
CALLING SEQUENCE:
MKHDR, header ;Prompt for image size and type
or
MKHDR, header, im, [ /IMAGE, /EXTEND ]
or
MKHDR, header, type, naxisx, [/IMAGE, /EXTEND ]
OPTIONAL INPUTS:
IM - If IM is a vector or array then the header will be made
appropriate to the size and type of IM. IM does not have
to be the actual data; it can be a dummy array of the same
type and size as the data. Set IM = '' to create a dummy
header with NAXIS = 0.
TYPE - If 2 parameters are supplied, then the second parameter
is interpreted as an integer giving the IDL datatype e.g.
1 - Byte, 2 - 16 bit integer, 4 - float, 3 - Long
NAXISX - Vector giving the size of each dimension (NAXIS1, NAXIS2,
etc.).
OUTPUT:
HEADER - image header, (string array) with required keywords
BITPIX, NAXIS, NAXIS1, ... Further keywords can be added
to the header with SXADDPAR.
OPTIONAL INPUT KEYWORDS:
/IMAGE = If set, then a minimal header for a FITS IMAGE extension
is created. An IMAGE extension header is identical to
a primary FITS header except the first keyword is
'XTENSION' = 'IMAGE' instead of 'SIMPLE ' = 'T'
/EXTEND = If set, then the keyword EXTEND is inserted into the file,
with the value of "T" (true). The EXTEND keyword can
optionally be included in a primary header, if the FITS file
contains extensions.
RESTRICTIONS:
(1) MKHDR should not be used to make an STSDAS header or a FITS
ASCII or Binary Table extension header. Instead use
SXHMAKE - to create a minimal STSDAS header
FXBHMAKE - to create a minimal FITS binary table header
FTCREATE - to create a minimal FITS ASCII table header
(2) Any data already in the header before calling MKHDR
will be destroyed.
EXAMPLE:
Create a minimal FITS header, Hdr, for a 30 x 40 x 50 INTEGER*2 array
IDL> mkhdr, Hdr, 2, [30,40,50]
Alternatively, if the array already exists as an IDL variable, Array,
IDL> mkhdr, Hdr, Array
PROCEDURES CALLED:
SXADDPAR, GET_DATE
REVISION HISTORY:
Written November, 1988 W. Landsman
May, 1990, Adapted for IDL Version 2.0, J. Isensee
Aug, 1997, Use SYSTIME(), new DATE format W. Landsman
Allow unsigned data types W. Landsman December 1999
Set BZERO = 0 for unsigned integer data W. Landsman January 2000
EXTEND keyword must immediately follow last NAXISi W. Landsman Sep 2000
Add FITS definition COMMENT to primary headers W. Landsman Oct. 2001
Allow (nonstandard) 64 bit integers W. Landsman Feb. 2003
Add V6.0 notation W. Landsman July 2012
(See astrolib/pro/mkhdr.pro)
MLINMIX_ERR
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NAME:
MLINMIX_ERR
PURPOSE:
Bayesian approach to multiple linear regression with errors in X and Y
EXPLANATION:
PERFORM LINEAR REGRESSION OF Y ON X WHEN THERE ARE MEASUREMENT
ERRORS IN BOTH VARIABLES. THE REGRESSION ASSUMES :
ETA = ALPHA + BETA ## XI + EPSILON
X = XI + XERR
Y = ETA + YERR
HERE, (ALPHA, BETA) ARE THE REGRESSION COEFFICIENTS, EPSILON IS THE
INTRINSIC RANDOM SCATTER ABOUT THE REGRESSION, XERR IS THE
MEASUREMENT ERROR IN X, AND YERR IS THE MEASUREMENT ERROR IN
Y. EPSILON IS ASSUMED TO BE NORMALLY-DISTRIBUTED WITH MEAN ZERO AND
VARIANCE SIGSQR. XERR AND YERR ARE ASSUMED TO BE
NORMALLY-DISTRIBUTED WITH MEANS EQUAL TO ZERO, COVARIANCE MATRICES
XVAR^2 FOR X, VARIANCES YSIG^2 FOR Y, AND COVARIANCE VECTORS
XYCOV. THE DISTRIBUTION OF XI IS MODELLED AS A MIXTURE OF NORMALS,
WITH GROUP PROPORTIONS PI, MEANS MU, AND COVARIANCES T. BAYESIAN
INFERENCE IS EMPLOYED, AND A STRUCTURE CONTAINING RANDOM DRAWS FROM
THE POSTERIOR IS RETURNED. CONVERGENCE OF THE MCMC TO THE POSTERIOR
IS MONITORED USING THE POTENTIAL SCALE REDUCTION FACTOR (RHAT,
GELMAN ET AL.2004). IN GENERAL, WHEN RHAT < 1.1 THEN APPROXIMATE
CONVERGENCE IS REACHED.
SIMPLE NON-DETECTIONS ON Y MAY ALSO BE INCLUDED
AUTHOR : BRANDON C. KELLY, STEWARD OBS., JULY 2006
INPUTS :
X - THE OBSERVED INDEPENDENT VARIABLES. THIS SHOULD BE AN
[NX, NP]-ELEMENT ARRAY.
Y - THE OBSERVED DEPENDENT VARIABLE. THIS SHOULD BE AN NX-ELEMENT
VECTOR.
OPTIONAL INPUTS :
XVAR - THE COVARIANCE MATRIX OF THE X ERRORS, AND
[NX,NP,NP]-ELEMENT ARRAY. XVAR[I,*,*] IS THE COVARIANCE
MATRIX FOR THE ERRORS ON X[I,*]. THE DIAGONAL OF
XVAR[I,*,*] MUST BE GREATER THAN ZERO FOR EACH DATA POINT.
YVAR - THE VARIANCE OF THE Y ERRORS, AND NX-ELEMENT VECTOR. YVAR
MUST BE GREATER THAN ZERO.
XYCOV - THE VECTOR OF COVARIANCES FOR THE MEASUREMENT ERRORS
BETWEEN X AND Y.
DELTA - AN NX-ELEMENT VECTOR INDICATING WHETHER A DATA POINT IS
CENSORED OR NOT. IF DELTA[i] = 1, THEN THE SOURCE IS
DETECTED, ELSE IF DELTA[i] = 0 THE SOURCE IS NOT DETECTED
AND Y[i] SHOULD BE AN UPPER LIMIT ON Y[i]. NOTE THAT IF
THERE ARE CENSORED DATA POINTS, THEN THE
MAXIMUM-LIKELIHOOD ESTIMATE (THETA) IS NOT VALID. THE
DEFAULT IS TO ASSUME ALL DATA POINTS ARE DETECTED, IE,
DELTA = REPLICATE(1, NX).
SILENT - SUPPRESS TEXT OUTPUT.
MINITER - MINIMUM NUMBER OF ITERATIONS PERFORMED BY THE GIBBS
SAMPLER. IN GENERAL, MINITER = 5000 SHOULD BE SUFFICIENT
FOR CONVERGENCE. THE DEFAULT IS MINITER = 5000. THE
GIBBS SAMPLER IS STOPPED AFTER RHAT < 1.1 FOR ALPHA,
BETA, AND SIGMA^2, AND THE NUMBER OF ITERATIONS
PERFORMED IS GREATER THAN MINITER.
MAXITER - THE MAXIMUM NUMBER OF ITERATIONS PERFORMED BY THE
MCMC. THE DEFAULT IS 1D5. THE GIBBS SAMPLER IS STOPPED
AUTOMATICALLY AFTER MAXITER ITERATIONS.
NGAUSS - THE NUMBER OF GAUSSIANS TO USE IN THE MIXTURE
MODELLING. THE DEFAULT IS 3.
OUTPUT :
POST - A STRUCTURE CONTAINING THE RESULTS FROM THE GIBBS
SAMPLER. EACH ELEMENT OF POST IS A DRAW FROM THE POSTERIOR
DISTRIBUTION FOR EACH OF THE PARAMETERS.
ALPHA - THE CONSTANT IN THE REGRESSION.
BETA - THE SLOPES OF THE REGRESSION.
SIGSQR - THE VARIANCE OF THE INTRINSIC SCATTER.
PI - THE GAUSSIAN WEIGHTS FOR THE MIXTURE MODEL.
MU - THE GAUSSIAN MEANS FOR THE MIXTURE MODEL.
T - THE GAUSSIAN COVARIANCE MATRICES FOR THE MIXTURE
MODEL.
MU0 - THE HYPERPARAMETER GIVING THE MEAN VALUE OF THE
GAUSSIAN PRIOR ON MU.
U - THE HYPERPARAMETER DESCRIBING FOR THE PRIOR
COVARIANCE MATRIX OF THE INDIVIDUAL GAUSSIAN
CENTROIDS ABOUT MU0.
W - THE HYPERPARAMETER DESCRIBING THE `TYPICAL' SCALE
MATRIX FOR THE PRIOR ON (T,U).
XIMEAN - THE MEAN OF THE DISTRIBUTION FOR THE
INDEPENDENT VARIABLE, XI.
XIVAR - THE STANDARD COVARIANCE MATRIX FOR THE
DISTRIBUTION OF THE INDEPENDENT VARIABLE, XI.
XICORR - SAME AS XIVAR, BUT FOR THE CORRELATION MATRIX.
CORR - THE LINEAR CORRELATION COEFFICIENT BETWEEN THE
DEPENDENT AND INDIVIDUAL INDEPENDENT VARIABLES,
XI AND ETA.
PCORR - SAME AS CORR, BUT FOR THE PARTIAL CORRELATIONS.
CALLED ROUTINES :
RANDOMCHI, MRANDOMN, RANDOMWISH, RANDOMDIR, MULTINOM
REFERENCES :
Carroll, R.J., Roeder, K., & Wasserman, L., 1999, Flexible
Parametric Measurement Error Models, Biometrics, 55, 44
Kelly, B.C., 2007, Some Aspects of Measurement Error in
Linear Regression of Astronomical Data, ApJ, In press
(astro-ph/0705.2774)
Gelman, A., Carlin, J.B., Stern, H.S., & Rubin, D.B., 2004,
Bayesian Data Analysis, Chapman & Hall/CRC
(See astrolib/pro/mlinmix_err.pro)
MMM
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NAME:
MMM
PURPOSE:
Estimate the sky background in a stellar contaminated field.
EXPLANATION:
MMM assumes that contaminated sky pixel values overwhelmingly display
POSITIVE departures from the true value. Adapted from DAOPHOT
routine of the same name.
CALLING SEQUENCE:
MMM, sky, [ skymod, sigma, skew, HIGHBAD = , READNOISE=, /DEBUG,
NSKY=, /INTEGER,/SILENT]
INPUTS:
SKY - Array or Vector containing sky values. This version of
MMM does not require SKY to be sorted beforehand. SKY
is unaltered by this program.
OPTIONAL OUTPUTS:
skymod - Scalar giving estimated mode of the sky values
SIGMA - Scalar giving standard deviation of the peak in the sky
histogram. If for some reason it is impossible to derive
skymod, then SIGMA = -1.0
SKEW - Scalar giving skewness of the peak in the sky histogram
If no output variables are supplied or if /DEBUG is set
then the values of skymod, SIGMA and SKEW will be printed.
OPTIONAL KEYWORD INPUTS:
HIGHBAD - scalar value of the (lowest) "bad" pixel level (e.g. cosmic
rays or saturated pixels) If not supplied, then there is
assumed to be no high bad pixels.
MINSKY - Integer giving mininum number of sky values to be used. MMM
will return an error if fewer sky elements are supplied.
Default = 20.
MAXITER - integer giving maximum number of iterations allowed,default=50
READNOISE - Scalar giving the read noise (or minimum noise for any
pixel). Normally, MMM determines the (robust) median by
averaging the central 20% of the sky values. In some cases
where the noise is low, and pixel values are quantized a
larger fraction may be needed. By supplying the optional
read noise parameter, MMM is better able to adjust the
fraction of pixels used to determine the median.
/INTEGER - Set this keyword if the input SKY vector only contains
discrete integer values. This keyword is only needed if the
SKY vector is of type float or double precision, but contains
only discrete integer values. (Prior to July 2004, the
equivalent of /INTEGER was set for all data types)
/DEBUG - If this keyword is set and non-zero, then additional
information is displayed at the terminal.
/SILENT - If set, then error messages will be suppressed when MMM
cannot compute a background. Sigma will still be set to -1
OPTIONAL OUTPUT KEYWORD:
NSKY - Integer scalar giving the number of pixels actually used for the
sky computation (after outliers have been removed).
NOTES:
(1) Program assumes that low "bad" pixels (e.g. bad CCD columns) have
already been deleted from the SKY vector.
(2) MMM was updated in June 2004 to better match more recent versions
of DAOPHOT.
(3) Does not work well in the limit of low Poisson integer counts
(4) MMM may fail for strongly skewed distributions.
METHOD:
The algorithm used by MMM consists of roughly two parts:
(1) The average and sigma of the sky pixels is computed. These values
are used to eliminate outliers, i.e. values with a low probability
given a Gaussian with specified average and sigma. The average
and sigma are then recomputed and the process repeated up to 20
iterations:
(2) The amount of contamination by stars is estimated by comparing the
mean and median of the remaining sky pixels. If the mean is larger
than the median then the true sky value is estimated by
3*median - 2*mean
REVISION HISTORY:
Adapted to IDL from 1986 version of DAOPHOT in STSDAS,
W. Landsman, STX Feb 1987
Added HIGHBAD keyword, W. Landsman January, 1991
Fixed occasional problem with integer inputs W. Landsman Feb, 1994
Avoid possible 16 bit integer overflow W. Landsman November 2001
Added READNOISE, NSKY keywords, new median computation
W. Landsman June 2004
Added INTEGER keyword W. Landsman July 2004
Improve numerical precision W. Landsman October 2004
Fewer aborts on strange input sky histograms W. Landsman October 2005
Added /SILENT keyword November 2005
Fix too many /CON keywords to MESSAGE W.L. December 2005
Fix bug introduced June 2004 removing outliers when READNOISE not set
N. Cunningham/W. Landsman January 2006
Make sure that MESSAGE never aborts W. Landsman January 2008
Add mxiter keyword and change default to 50 W. Landsman August 2011
Added MINSKY keyword W.L. December 2011
(See astrolib/pro/mmm.pro)
MODFITS
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NAME:
MODFITS
PURPOSE:
Modify a FITS file by updating the header and/or data array.
EXPLANATION:
Update the data and/or header in a specified FITS extension or primary
HDU.
The size of the supplied FITS header or data array does not
need to match the size of the existing header or data array.
CALLING SEQUENCE:
MODFITS, Filename_or_fcb, Data, [ Header, EXTEN_NO =, EXTNAME= , ERRMSG=]
INPUTS:
FILENAME/FCB = Scalar string containing either the name of the FITS file
to be modified, or the IO file control block returned after
opening the file with FITS_OPEN,/UPDATE. The explicit
use of FITS_OPEN can save time if many extensions in a
single file will be updated.
DATA - data array to be inserted into the FITS file. Set DATA = 0
to leave the data portion of the FITS file unmodified. Data
can also be an IDL structure (e.g. as returned by MRDFITS).
provided that it does not include IDL pointers.
HEADER - FITS header (string array) to be updated in the FITS file.
OPTIONAL INPUT KEYWORDS:
A specific extension can be specified with either the EXTNAME or
EXTEN_NO keyword
EXTEN_NO - scalar integer specifying the FITS extension to modified. For
example, specify EXTEN = 1 or /EXTEN to modify the first
FITS extension.
EXTNAME - string name of the extension to modify.
OPTIONAL OUTPUT KEYWORD:
ERRMSG - If this keyword is supplied, then any error mesasges will be
returned to the user in this parameter rather than depending on
on the MESSAGE routine in IDL. If no errors are encountered
then a null string is returned.
EXAMPLES:
(1) Modify the value of the DATE keyword in the primary header of a
file TEST.FITS.
IDL> h = headfits('test.fits') ;Read primary header
IDL> sxaddpar,h,'DATE','2001-03-23' ;Modify value of DATE
IDL> modfits,'test.fits',0,h ;Update header only
(2) Replace the values of the primary image array in 'test.fits' with
their absolute values
IDL> im = readfits('test.fits') ;Read image array
IDL> im = abs(im) ;Take absolute values
IDL> modfits,'test.fits',im ;Update image array
(3) Add some HISTORY records to the FITS header in the first extension
of a file 'test.fits'
IDL> h = headfits('test.fits',/ext) ;Read first extension hdr
IDL> sxaddhist,['Comment 1','Comment 2'],h
IDL> modfits,'test.fits',0,h,/ext ;Update extension hdr
(4) Change 'OBSDATE' keyword to 'OBS-DATE' in every extension in a
FITS file. Explicitly open with FITS_OPEN to save compute time.
fits_open,'test.fits',io,/update ;Faster to explicity open
for i = 1,nextend do begin ;Loop over extensions
fits_read,io,0,h,/header_only,exten_no=i,/No_PDU ;Get header
date= sxpar(h,'OBSDATE') ;Save keyword value
sxaddpar,h,'OBS-DATE',date,after='OBSDATE'
sxdelpar,h,'OBSDATE' ;Delete bad keyword
modfits,io,0,h,exten_no=i ;Update header
endfor
Note the use of the /No_PDU keyword in the FITS_READ call -- one
does *not* want to append the primary header, if the STScI
inheritance convention is adopted.
NOTES:
Uses the BLKSHIFT procedure to shift the contents of the FITS file if
the new data or header differs in size by more than 2880 bytes from the
old data or header. If a file control block (FCB) structure is
supplied, then the values of START_HEADER, START_DATA and NBYTES may
be modified if the file size changes.
Also see the procedures FXHMODIFY to add a single FITS keyword to a
header in a FITS files, and FXBGROW to enlarge the size of a binary
table.
RESTRICTIONS:
(1) Cannot be used to modify the data in FITS files with random
groups or variable length binary tables. (The headers in such
files *can* be modified.)
(2) If a data array but no FITS header is supplied, then MODFITS does
not check to make sure that the existing header is consistent with
the new data.
(3) Does not work with compressed files
(4) The Checksum keywords will not be updated if the array to be
updated is supplied as a structure (e.g. from MRDFITS).
PROCEDURES USED:
Functions: N_BYTES(), SXPAR()
Procedures: BLKSHIFT, CHECK_FITS, FITS_OPEN, FITS_READ
MODIFICATION HISTORY:
Written, Wayne Landsman December, 1994
Fixed possible problem when using WRITEU after READU October 1997
New and old sizes need only be the same within multiple of 2880 bytes
Added call to IS_IEEE_BIG() W. Landsman May 1999
Added ERRMSG output keyword W. Landsman May 2000
Update tests for incompatible sizes W. Landsman December 2000
Major rewrite to use FITS_OPEN procedures W. Landsman November 2001
Add /No_PDU call to FITS_READ call W. Landsman June 2002
Update CHECKSUM keywords if already present in header, add padding
if new data size is smaller than old W.Landsman December 2002
Only check XTENSION value if EXTEN_NO > 1 W. Landsman Feb. 2003
Correct for unsigned data on little endian machines W. Landsman Apr 2003
Major rewrite to allow changing size of data or header W.L. Aug 2003
Fixed case where updated header exactly fills boundary W.L. Feb 2004
More robust error reporting W.L. Dec 2004
Make sure input header ends with a END W.L. March 2006
Assume since V5.5, remove VMS support, assume FITS_OPEN will
perform byte swapping W.L. Sep 2006
Update FCB structure if file size changes W.L. March 2007
Fix problem when data size must be extended W.L. August 2007
Don't assume supplied FITS header is 80 bytes W. L. Dec 2007
Check for new END position after adding CHECKSUM W.L. July 2008
Added EXTNAME input keyword W.L. July 2008
Allow data to be an IDL structure A. Conley/W.L. June 2009
Use V6.0 notation, add /NOZERO to BLKSHIFT W.L. Feb 2011
Don't try to update Checksums when structure supplied W.L. April 2011
Allow structure with only 1 element W.L. Feb 2012
(See astrolib/pro/modfits.pro)
MONTH_CNV
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NAME:
MONTH_CNV
PURPOSE:
Convert between a month name and the equivalent number
EXPLANATION: (e.g.,
For example, converts from 'January' to 1 or vice-versa.
CALLING SEQUENCE:
Result = MONTH_CNV( MonthInput, [/UP, /LOW, /SHORT ] )
INPUTS:
MonthInput - either a string ('January', 'Jan', 'Decem', etc.) or
an number from 1 to 12. Scalar or array.
OPTIONAL KEYWORDS:
UP - if set and if a string is being returned, it will be in all
uppercase letters.
LOW - if set and if a string is being returned, it will be in all
lowercase letters.
SHORT - if set and if a string is being returned, only the first
three letters are returned.
OUTPUTS:
If the input is a string, the output is the matching month number.If
an input string isn't a valid month name, -1 is returned.
If the input is a number, the output is the matching month name. The
default format is only the first letter is capitalized.
EXAMPLE:
To get a vector of all the month names:
Names = month_cnv(indgen(12)+1)
MODIFICATION HISTORY:
Written by: Joel Wm. Parker, SwRI, 1998 Dec 9
(See astrolib/pro/month_cnv.pro)
MOONPOS
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NAME:
MOONPOS
PURPOSE:
To compute the RA and Dec of the Moon at specified Julian date(s).
CALLING SEQUENCE:
MOONPOS, jd, ra, dec, dis, geolong, geolat, [/RADIAN ]
INPUTS:
JD - Julian ephemeris date, scalar or vector, double precision suggested
OUTPUTS:
Ra - Apparent right ascension of the moon in DEGREES, referred to the
true equator of the specified date(s)
Dec - The declination of the moon in DEGREES
Dis - The Earth-moon distance in kilometers (between the center of the
Earth and the center of the Moon).
Geolong - Apparent longitude of the moon in DEGREES, referred to the
ecliptic of the specified date(s)
Geolat - Apparent longitude of the moon in DEGREES, referred to the
ecliptic of the specified date(s)
The output variables will all have the same number of elements as the
input Julian date vector, JD. If JD is a scalar then the output
variables will be also.
OPTIONAL INPUT KEYWORD:
/RADIAN - If this keyword is set and non-zero, then all output variables
are given in Radians rather than Degrees
EXAMPLES:
(1) Find the position of the moon on April 12, 1992
IDL> jdcnv,1992,4,12,0,jd ;Get Julian date
IDL> moonpos, jd, ra ,dec ;Get RA and Dec of moon
IDL> print,adstring(ra,dec,1)
==> 08 58 45.23 +13 46 6.1
This is within 1" from the position given in the Astronomical Almanac
(2) Plot the Earth-moon distance for every day at 0 TD in July, 1996
IDL> jdcnv,1996,7,1,0,jd ;Get Julian date of July 1
IDL> moonpos,jd+dindgen(31), ra, dec, dis ;Position at all 31 days
IDL> plot,indgen(31),dis, /YNOZ
METHOD:
Derived from the Chapront ELP2000/82 Lunar Theory (Chapront-Touze' and
Chapront, 1983, 124, 50), as described by Jean Meeus in Chapter 47 of
``Astronomical Algorithms'' (Willmann-Bell, Richmond), 2nd edition,
1998. Meeus quotes an approximate accuracy of 10" in longitude and
4" in latitude, but he does not give the time range for this accuracy.
Comparison of this IDL procedure with the example in ``Astronomical
Algorithms'' reveals a very small discrepancy (~1 km) in the distance
computation, but no difference in the position calculation.
This procedure underwent a major rewrite in June 1996, and the new
calling sequence is *incompatible with the old* (e.g. angles now
returned in degrees instead of radians).
PROCEDURES CALLED:
CIRRANGE, ISARRAY(), NUTATE, TEN() - from IDL Astronomy Library
POLY() - from IDL User's Library
MODIFICATION HISTORY:
Written by Michael R. Greason, STX, 31 October 1988.
Major rewrite, new (incompatible) calling sequence, much improved
accuracy, W. Landsman Hughes STX June 1996
Added /RADIAN keyword W. Landsman August 1997
Converted to IDL V5.0 W. Landsman September 1997
Use improved expressions for L',D,M,M', and F given in 2nd edition of
Meeus (very slight change), W. Landsman November 2000
Avoid 32767 overflow W. Landsman January 2005
(See astrolib/pro/moonpos.pro)
MPHASE
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NAME:
MPHASE
PURPOSE:
Return the illuminated fraction of the Moon at given Julian date(s)
CALLING SEQUENCE:
MPHASE, jd, k
INPUT:
JD - Julian date, scalar or vector, double precision recommended
OUTPUT:
k - illuminated fraction of Moon's disk (0.0 < k < 1.0), same number
of elements as jd. k = 0 indicates a new moon, while k = 1 for
a full moon.
EXAMPLE:
Plot the illuminated fraction of the moon for every day in July
1996 at 0 TD (~Greenwich noon).
IDL> jdcnv, 1996, 7, 1, 0, jd ;Get Julian date of July 1
IDL> mphase, jd+dindgen(31), k ;Moon phase for all 31 days
IDL> plot, indgen(31),k ;Plot phase vs. July day number
METHOD:
Algorithm from Chapter 46 of "Astronomical Algorithms" by Jean Meeus
(Willmann-Bell, Richmond) 1991. SUNPOS and MOONPOS are used to get
positions of the Sun and the Moon (and the Moon distance). The
selenocentric elongation of the Earth from the Sun (phase angle)
is then computed, and used to determine the illuminated fraction.
PROCEDURES CALLED:
MOONPOS, SUNPOS
REVISION HISTORY:
Written W. Landsman Hughes STX June 1996
Converted to IDL V5.0 W. Landsman September 1997
Use /RADIAN keywords to MOONPOS, SUNPOS internally W. Landsman Aug 2000
(See astrolib/pro/mphase.pro)
MRANDOMN
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NAME:
MRANDOMN
PURPOSE:
Function to draw NRAND random deviates from a multivariate normal
distribution with zero mean and covariance matrix COVAR.
AUTHOR : Brandon C. Kelly, Steward Obs., Sept. 2004
INPUTS :
SEED - The random number generator seed, the default is IDL's
default in RANDOMN()
COVAR - The covariance matrix of the multivariate normal
distribution.
OPTIONAL INPUTS :
NRAND - The number of randomn deviates to draw. The default is
one.
OUTPUT :
The random deviates, an [NRAND, NP] array where NP is the
dimension of the covariance matrix, i.e., the number of
parameters.
ROUTINES CALLED :
POSITIVE, DIAG
(See astrolib/pro/mrandomn.pro)
MRDFITS
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NAME:
MRDFITS
PURPOSE:
Read all standard FITS data types into arrays or structures.
EXPLANATION:
Further information on MRDFITS is available at
http://idlastro.gsfc.nasa.gov/mrdfits.html
**This version requires a post March 2009 version of fxposit.pro**
CALLING SEQUENCE:
Result = MRDFITS( Filename/FileUnit,[Exten_no/Exten_name, Header],
/FPACK, /NO_FPACK, /FSCALE , /DSCALE , /UNSIGNED,
ALIAS=strarr[2,n], /USE_COLNUM,
/NO_TDIM, ROWS = [a,b,...], $
/POINTER_VAR, /FIXED_VAR, EXTNUM=
RANGE=[a,b], COLUMNS=[a,b,...]), ERROR_ACTION=x,
COMPRESS=comp_prog, STATUS=status, /VERSION,
/EMPTYSTRING )
INPUTS:
Filename = String containing the name of the file to be read or
file number of an open unit. If an empty string is supplied,
then user will be prompted for the file name. The user
will also be prompted if a wild card is given in the file
name, and there is more than one file name match.
If the file name ends in .gz or .fz (or .Z on Unix systems)
the file will be dynamically decompressed.
or
FiluUnit = An integer file unit which has already been
opened for input. Data will be read from this
unit and the unit will be left pointing immediately
after the HDU that is read. Thus to read a compressed
file with many HDU's a user might do something like:
lun=fxposit(filename, 3) ; Skip the first three HDU's
repeat begin
thisHDU = mrdfits(lun, 0, hdr, status=status)
... process the HDU ...
endrep until status lt 0
Exten_no= Extension number to be read, 0 for primary array.
Assumed 0 if not specified.
If a unit rather than a filename
is specified in the first argument, this is
the number of HDU's to skip from the current position.
Exten_name - Name of the extension to read (as stored in the EXTNAME
keyword). This is a slightly slower method then specifying
the extension number.
OUTPUTS:
Result = FITS data array or structure constructed from
the designated extension. The format of result depends
upon the type of FITS data read.
Non-group primary array or IMAGE extension:
A simple multidimensional array is returned with the
dimensions given in the NAXISn keywords.
Grouped image data with PCOUNT=0.
As above but with GCOUNT treated as NAXIS(n+1).
Grouped image data with PCOUNT>0.
The data is returned as an array of structures. Each
structure has two elements. The first is a one-dimensional
array of the group parameters, the second is a multidimensional
array as given by the NAXIS2-n keywords.
ASCII and BINARY tables.
The data is returned as a structure with one column for
each field in the table. The names of the columns are
normally taken from the TTYPE keywords (but see USE_COLNUM).
Bit field columns
are stored in byte arrays of the minimum necessary
length. Spaces and invalid characters are replaced by
underscores, and other invalid tag names are converted using
the IDL_VALIDNAME(/CONVERT_ALL) function.
Columns specified as variable length columns are stored
with a dimension equal to the largest actual dimension
used. Extra values in rows are filled with 0's or blanks.
If the size of the variable length column is not
a constant, then an additional column is created giving the
size used in the current row. This additional column will
have a tag name of the form L#_"colname" where # is the column
number and colname is the column name of the variable length
column. If the length of each element of a variable length
column is 0 then the column is deleted.
OPTIONAL OUTPUT:
Header = String array containing the header from the FITS extension.
OPTIONAL INPUT KEYWORDS:
ALIAS The keyword allows the user to specify the column names
to be created when reading FITS data. The value of
this keyword should be a 2xn string array. The first
value of each pair of strings should be the desired
tag name for the IDL column. The second should be
the FITS TTYPE value. Note that there are restrictions
on valid tag names. The order of the ALIAS keyword
is compatible with MWRFITS.
COLUMNS - This keyword allows the user to specify that only a
subset of columns is to be returned. The columns
may be specified either as number 1,... n or by
name or some combination of these two.
If /USE_COLNUM is specified names should be C1,...Cn.
The use of this keyword will not save time or internal
memory since the extraction of specified columns
is done after all columns have been retrieved from the
FITS file. Structure columns are returned in the order
supplied in this keyword.
COMPRESS - This keyword allows the user to specify a
decompression program to use to decompress a file that
will not be automatically recognized based upon
the file name.
/DSCALE - As with FSCALE except that the resulting data is
stored in doubles.
/EMPTYSTRING - There was a bug in memory management for IDL versions
prior to V8.0, causing a memory leak when reading
empty strings in a FITS table. Setting /EMPTYSTRING will
avoid this problem by first reading strings into bytes and
then converting. However, there is a performance penalty.
ERROR_ACTION - Set the on_error action to this value (defaults
to 2).
/FIXED_VAR- Translate variable length columns into fixed length columns
and provide a length column for truly varying columns.
This was only behavior prior to V2.5 for MRDFITS and remains
the default (see /POINTER_VAR)
/FPACK - If set, then assume the FITS file uses FPACK compression
(http://heasarc.gsfc.nasa.gov/fitsio/fpack/). To read
an FPACK compressed file, either this must be set or the
file name must end in ".fz"
/NO_FPACK - If present, then MRDFITS will not uncompress an extension
compressed with FPACK (i.e with a .fz extension), but will
just read the compressed binary stream.
/FSCALE - If present and non-zero then scale data to float
numbers for arrays and columns which have either
non-zero offset or non-unity scale.
If scaling parameters are applied, then the corresponding
FITS scaling keywords will be modified.
NO_TDIM - Disable processing of TDIM keywords. If NO_TDIM
is specified MRDFITS will ignore TDIM keywords in
binary tables.
/POINTER_VAR- Use pointer arrays for variable length columns.
In addition to changing the format in which
variable length arrays are stored, if the pointer_var
keyword is set to any value other than 1 this also disables
the deletion of variable length columns. (See /FIXED_VAR)
Note that because pointers may be present in the output
structure, the user is responsible for memory management
when deleting or reassigning the structure (e.g. use HEAP_FREE
first).
RANGE - A scalar or two element vector giving the start
and end rows to be retrieved. For ASCII and BINARY
tables this specifies the row number. For GROUPed data
this will specify the groups. For array images, this
refers to the last non-unity index in the array. E.g.,
for a 3 D image with NAXIS* values = [100,100,1], the
range may be specified as 0:99, since the last axis
is suppressed. Note that the range uses IDL indexing
So that the first row is row 0.
If only a single value, x, is given in the range,
the range is assumed to be [0,x-1].
ROWS - A scalar or vector specifying a specific row or rows to read
(first row is 0). For example to read rows 0,
12 and 23 only, set ROWS=[0,12,23]. Valid for images, ASCII
and binary tables, but not GROUPed data. For images
the row numbers refer to the last non-unity index in the array.
Note that the use of the ROWS will not improve the speed of
MRDFITS since the entire table will be read in, and then subset
to the specified rows. Cannot be used at the same time as
the RANGE keyword
/SILENT - Suppress informative messages.
STRUCTYP - The structyp keyword specifies the name to be used
for the structure defined when reading ASCII or binary
tables. Generally users will not be able to conveniently
combine data from multiple files unless the STRUCTYP
parameter is specified. An error will occur if the
user specifies the same value for the STRUCTYP keyword
in calls to MRDFITS in the same IDL session for extensions
which have different structures.
/UNSIGNED - For integer data with appropriate zero points and scales
read the data into unsigned integer arrays.
/USE_COLNUM - When creating column names for binary and ASCII tables
MRDFITS attempts to use the appropriate TTYPE keyword
values. If USE_COLNUM is specified and non-zero then
column names will be generated as 'C1, C2, ... 'Cn'
for the number of columns in the table.
/VERSION Print the current version number
OPTIONAL OUTPUT KEYWORDS:
EXTNUM - the number of the extension actually read. Useful if the
user specified the extension by name.
OUTALIAS - This is a 2xn string array where the first column gives the
actual structure tagname, and the second gives the
corresponding FITS keyword name (e.g. in the TTYPE keyword).
This array can be passed directly to
the alias keyword of MWRFITS to recreate the file originally
read by MRDFITS.
STATUS - A integer status indicating success or failure of
the request. A status of >=0 indicates a successful read.
Currently
0 -> successful completion
-1 -> error
-2 -> end of file
EXAMPLES:
(1) Read a FITS primary array:
a = mrdfits('TEST.FITS') or
a = mrdfits('TEST.FITS', 0, header)
The second example also retrieves header information.
(2) Read rows 10-100 of the second extension of a FITS file.
a = mrdfits('TEST.FITS', 2, header, range=[10,100])
(3) Read a table and ask that any scalings be applied and the
scaled data be converted to doubles. Use simple column names,
suppress outputs.
a = mrdfits('TEST.FITS', 1, /dscale, /use_colnum, /silent)
(4) Read rows 3, 34 and 52 of a binary table and request that
variable length columns be stored as a pointer variable in the
output structure
a = mrdfits('TEST.FITS',1,rows=[3,34,52],/POINTER)
RESTRICTIONS:
(1) Cannot handle data in non-standard FITS formats.
(2) Doesn't do anything with BLANK or NULL values or
NaN's. They are just read in. They may be scaled
if scaling is applied.
(3) Does not automatically detect a FPACK compressed file. Either
the file name must end in .fz, or the /FPACK keyword must
be set
NOTES:
This multiple format FITS reader is designed to provide a
single, simple interface to reading all common types of FITS data.
MRDFITS DOES NOT scale data by default. The FSCALE or DSCALE
parameters must be used.
Null values in an FITS ASCII table are converted to NaN (floating data),
or -2147483647L (longwords) or '...' (strings).
PROCEDURES USED:
The following procedures are contained in the main MRDFITS program.
MRD_IMAGE -- Generate array/structure for images.
MRD_READ_IMAGE -- Read image data.
MRD_ASCII -- Generate structure for ASCII tables.
MRD_READ_ASCII -- Read an ASCII table.
MRD_TABLE -- Generate structure for Binary tables.
MRD_READ_TABLE -- Read binary table info.
MRD_READ_HEAP -- Read variable length record info.
MRD_SCALE -- Apply scaling to data.
MRD_COLUMNS -- Extract columns.
Other ASTRON Library routines used
FXPAR(), FXADDPAR, FXPOSIT, FXMOVE(), MATCH, MRD_STRUCT(), MRD_SKIP
MODIfICATION HISTORY:
V1.0 November 9, 1994 ---- Initial release.
Creator: Thomas A. McGlynn
V1.1 January 20, 1995 T.A. McGlynn
Fixed bug in variable length records.
Added TDIM support -- new routine mrd_tdim in MRD_TABLE.
V1.2
Added support for dynamic decompression of files.
Fixed further bugs in variable length record handling.
V1.2a
Added NO_TDIM keyword to turn off TDIM processing for
those who don't want it.
Bug fixes: Handle one row tables correctly, use BZERO rather than
BOFFSET. Fix error in scaling of images.
V1.2b
Changed MRD_HREAD to handle null characters in headers.
V2.0 April 1, 1996
-Handles FITS tables with an arbitrary number of columns.
-Substantial changes to MRD_STRUCT to allow the use of
substructures when more than 127 columns are desired.
-All references to table columns are now made through the
functions MRD_GETC and MRD_PUTC. See description above.
-Use of SILENT will now eliminate compilation messages for
temporary functions.
-Bugs in handling of variable length columns with either
a single row in the table or a maximum of a single element
in the column fixed.
-Added support for DCOMPLEX numbers in binary tables (M formats) for
IDL versions above 4.0.
-Created regression test procedure to check in new versions.
-Added error_action parameter to allow user to specify
on_error action. This should allow better interaction with
new CHECK facility. ON_ERROR statements deleted from
most called routines.
- Modified MRDFITS to read in headers containing null characters
with a warning message printed.
V2.0a April 16, 1996
- Added IS_IEEE_BIG() checks (and routine) so that we don't
worry about IEEE to host conversions if the machine's native
format is IEEE Big-endian.
V2.1 August 24, 1996
- Use resolve_routine for dynamically defined functions
for versions > 4.0
- Fix some processing in random groups format.
- Handle cases where the data segment is--legally--null.
In this case MRDFITS returns a scalar 0.
- Fix bugs with the values for BSCALE and BZERO (and PSCAL and
PZERO) parameters set by MRDFITS.
V2.1a April 24, 1997 Handle binary tables with zero length columns
V2.1b May 13,1997 Remove whitespace from replicate structure definition
V2.1c May 28,1997 Less strict parsing of XTENSION keyword
V2.1d June 16, 1997 Fixed problem for >32767 entries introduced 24-Apr
V2.1e Aug 12, 1997 Fixed problem handling double complex arrays
V2.1f Oct 22, 1997 IDL reserved words can't be structure tag names
V2.1g Nov 24, 1997 Handle XTENSION keywords with extra blanks.
V2.1h Jul 26, 1998 More flexible parsing of TFORM characters
V2.2 Dec 14, 1998 Allow fields with longer names for
later versions of IDL.
Fix handling of arrays in scaling routines.
Allow >128 fields in structures for IDL >4.0
Use more efficient structure copying for
IDL>5.0
V2.2b June 17, 1999 Fix bug in handling case where
all variable length columns are deleted
because they are empty.
V2.3 March 7, 2000 Allow user to supply file handle rather
than file name.
Added status field.
Now needs FXMOVE routine
V2.3b April 4, 2000
Added compress option (from D. Palmer)
V2.4 July 4, 2000 Added STATUS=-1 for "File access error" (Zarro/GSFC)
V2.4a May 2, 2001 Trim binary format string (W. Landsman)
V2.5 December 5, 2001 Add unsigned, alias, 64 bit integers. version, $
/pointer_val, /fixed_var.
V2.5a Fix problem when both the first and the last character
in a TTYPEnn value are invalid structure tag characters
V2.6 February 15, 2002 Fix error in handling unsigned numbers, $
and 64 bit unsigneds. (Thanks to Stephane Beland)
V2.6a September 2, 2002 Fix possible conflicting data structure for
variable length arrays (W. Landsman)
V2.7 July, 2003 Added Rows keyword (W. Landsman)
V2.7a September 2003 Convert dimensions to long64 to handle huge files
V2.8 October 2003 Use IDL_VALIDNAME() function to ensure valid tag names
Removed OLD_STRUCT and TEMPDIR keywords W. Landsman
V2.9 February 2004 Added internal MRD_FXPAR procedure for faster
processing of binary table headers E. Sheldon
V2.9a March 2004 Restore ability to read empty binary table W. Landsman
Swallow binary tables with more columns than given in TFIELDS
V2.9b Fix to ensure order of TFORMn doesn't matter
V2.9c Check if extra degenerate NAXISn keyword are present W.L. Oct 2004
V2.9d Propagate /SILENT to MRD_HREAD, more LONG64 casting W. L. Dec 2004
V2.9e Add typarr[good] to fix a problem reading zero-length columns
A.Csillaghy, [email protected] (RHESSI)
V2.9f Fix problem with string variable binary tables, possible math
overflow on non-IEEE machines WL Feb. 2005
V2.9g Fix problem when setting /USE_COLNUM WL Feb. 2005
V2.10 Use faster keywords to BYTEORDER WL May 2006
V2.11 Add ON_IOERROR, CATCH, and STATUS keyword to MRD_READ_IMAGE to
trap EOF in compressed files DZ Also fix handling of unsigned
images when BSCALE not present K Chu/WL June 2006
V2.12 Allow extension to be specified by name, added EXTNUM keyword
WL December 2006
V2.12a Convert ASCII table column to DOUBLE if single precision is
insufficient
V2.12b Fixed problem when both /fscale and /unsigned are set
C. Markwardt Aug 2007
V2.13 Use SWAP_ENDIAN_INPLACE instead of IEEE_TO_HOST and IS_IEEE_BIG
W. Landsman Nov 2007
V2.13a One element vector allowed for file name W.L. Dec 2007
V2.13b More informative error message when EOF found W.L. Jun 2008
V2.14 Use vector form of VALID_NUM(), added OUTALIAS keyword
W.L. Aug 2008
V2.15 Use new FXPOSIT which uses on-the-fly byteswapping W.L. Mar 2009
V2.15a Small efficiency updates to MRD_SCALE W.L. Apr 2009
V2.15b Fixed typo introduced Apr 2009
V2.15c Fix bug introduced Mar 2009 when file unit used W.L. July 2009
V2.16 Handle FPACK compressed files W. L. July 2009
V2.17 Use compile_opt hidden on all routines except mrdfits.pro W.L. July 2009
V2.18 Added /EMPTYSTRING keyword W. Landsman August 2009
V2.18a Fix Columns keyword output, A. Kimball/ W. Landsman Feb 2010
V2.18b Fix bug with /EMPTYSTRING and multidimensional strings
S. Baldridge/W.L. August 2010
V2.18c Fix unsigned bug caused by compile_opt idl2 WL Nov 2010
V2.19 Use V6.0 operators WL Nov 2010
V2.19a Fix complex data conversion in variable length tables WL Dec 2010
V2.19b Fix bug with /FSCALE introduced Nov 2010 WL Jan 2011
V2.19c Fix bug with ROWS keyword introduced Nov 2010 WL Mar 2011
V2.20 Convert Nulls in ASCII tables, better check of duplicate keywords
WL May 2011
V2.20a Better error checking for FPACK files WL October 2012
(See astrolib/pro/mrdfits.pro)
MRD_HREAD
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NAME:
MRD_HREAD
PURPOSE:
Reads a FITS header from an opened disk file or Unix pipe
EXPLANATION:
Like FXHREAD but also works with compressed Unix files
CALLING SEQUENCE:
MRD_HREAD, UNIT, HEADER [, STATUS, /SILENT, ERRMSG =, /FIRSTBLOCK ]
INPUTS:
UNIT = Logical unit number of an open FITS file
OUTPUTS:
HEADER = String array containing the FITS header.
OPT. OUTPUTS:
STATUS = Condition code giving the status of the read. Normally, this
is zero, but is set to -1 if an error occurs, or if the
first byte of the header is zero (ASCII null).
OPTIONAL KEYWORD INPUT:
/FIRSTBLOCK - If set, then only the first block (36 lines or less) of
the FITS header are read into the output variable. If only
size information (e.g. BITPIX, NAXIS) is needed from the
header, then the use of this keyword can save time. The
file pointer is still positioned at the end of the header,
even if the /FIRSTBLOCK keyword is supplied.
/SILENT - If set, then warning messages about any invalid characters in
the header are suppressed.
/SKIPDATA - If set, then the file point is positioned at the end of the
HDU after the header is read, i.e. the following data block
is skipped. Useful, when one wants to the read the headers
of multiple extensions.
/NO_BADHEADER - if set, returns if FITS header has illegal characters
By default, MRD_HREAD replaces bad characters with blanks,
issues a warning, and continues.
OPTIONAL OUTPUT PARAMETER:
ERRMSG = If this keyword is present, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned.
RESTRICTIONS:
The file must already be positioned at the start of the header. It
must be a proper FITS file.
SIDE EFFECTS:
The file ends by being positioned at the end of the FITS header, unless
an error occurs.
REVISION HISTORY:
Written, Thomas McGlynn August 1995
Modified, Thomas McGlynn January 1996
Changed MRD_HREAD to handle Headers which have null characters
A warning message is printed out but the program continues.
Previously MRD_HREAD would fail if the null characters were
not in the last 2880 byte block of the header. Note that
such characters are illegal in the header but frequently
are produced by poor FITS writers.
Added /SILENT keyword W. Landsman December 2000
Added /FIRSTBLOCK keyword W. Landsman February 2003
Added ERRMSG, SKIPDATA keyword W. Landsman April 2009
Close file unit even after error message W.L. October 2010
Added /NO_BADHEADER Zarro (ADNET), January 2012
(See astrolib/pro/mrd_hread.pro)
MRD_SKIP
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NAME:
MRD_SKIP
PURPOSE:
Skip a number of bytes from the current location in a file or a pipe
EXPLANATION:
First tries using POINT_LUN and if this doesn't work, perhaps because
the unit is a pipe or a socket, MRD_SKIP will just read in the
requisite number of bytes.
CALLING SEQUENCE:
MRD_SKIP, Unit, Nskip
INPUTS:
Unit - File unit for the file or pipe in question, integer scalar
Nskip - Number of bytes to be skipped, positive integer
NOTES:
This routine should be used in place of POINT_LUN wherever a pipe
or socket may be the input unit (see the procedure FXPOSIT for an
example). Note that it assumes that it can only work with nskip >= 0
so it doesn't even try for negative values.
For reading a pipe, MRD_SKIP currently uses a maximum buffer size
of 8 MB. This chunk value can be increased for improved efficiency
(or decreased if you really have little memory.)
REVISION HISTORY:
Written, Thomas A. McGlynn July 1995
Don't even try to skip bytes on a pipe with POINT_LUN, since this
might reset the current pointer W. Landsman April 1996
Increase buffer size, check fstat.compress W. Landsman Jan 2001
Only a warning if trying read past EOF W. Landsman Sep 2001
Use 64bit longword for skipping in very large files W. Landsman Sep 2003
Assume since V5.4, fstat.compress available W. Landsman April 2006
POINT_LUN for compressed files is as fast as any W. Landsman Oct 2006
Don't try to use POINT_LUN on compressed files W. Landsman Dec. 2006
(See astrolib/pro/mrd_skip.pro)
MRD_STRUCT
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NAME:
MRD_STRUCT
PURPOSE:
Return a structure as defined in the names and values data.
CALLING SEQUENCE:
struct = MRD_STRUCT(NAMES, VALUES, NROW, STRUCTYP='name' )
INPUT PARAMETERS:
NAMES = A string array of names of structure fields.
VALUES = A string array giving the values of the structure
fields. See examples below.
NROW = The number of elements in the structure array.
RETURNS:
A structure as described in the parameters or 0 if an error
is detected.
OPTIONAL KEYWORD PARAMETERS:
/NO_EXECUTE - If set then the use of the EXECUTE() statement is avoided.
By default, the NO_EXECUTE pathway is used if IDL is
running under the Virtual Machine. Note if /NO_EXECUTE
is set, then the user cannot supply arbitary values, but
all possible values used by MRDFITS will be allowed.
STRUCTYP = The structure type. Since IDL does not allow the
redefinition of a named structure it is an error
to call MRD_STRUCT with different parameters but
the same STRUCTYP in the same session. If this
keyword is not set an anonymous structure is created.
COMMON BLOCKS:
MRD_COMMON
SIDE EFFECTS:
May create a temporary file if the structure definition is too long
for the EXECUTE function and using old style structures
RESTRICTIONS:
By default, the program defines the structure in a long string
which is executed with CREATE_STRUCT within a single EXECUTE statement.
If program is being run in the IDL Virtual machine (EXECUTE statement
not allowed), then a separate CREATE_STRUCT statement is called
for each tag. This mode does not have the full capabilities of the
normal mode, but should be sufficient for use with MRDFITS().
PROCEDURE:
A structure definition is created using the parameter values.
MRD_NSTRUCT is called and generates the structure in pieces using the
execute and create_struct keywords.
EXAMPLES:
(1) str = mrd_struct(['fld1', 'fld2'], ['0','dblarr(10,10)'],3)
print, str(0).fld2(3,3)
Note that "0" is always considered short integer even if the default
integer is set to long.
(2) str = mrd_struct(['a','b','c','d'],['1', '1.', '1.d0', "'1'"],1)
; returns a structure with integer, float, double and string
; fields.
PROCEDURE CALLS:
GETTOK() - needed for virtual machine mode only
MODIFICATION HISTORY:
Created by T. McGlynn October, 1994.
Modified by T. McGlynn September, 1995.
Added capability to create substructures so that structure
may contain up to 4096 distinct elements. [This can be
increased by futher iteration of the process used if needed.]
Removed V4.0 reference to common block October 1997
Allowed unlimited number of structure elements if the version
is greater than 5.0. Put back in code to handle prior versions.
The [] will need to be translated back to () for this to
work. T. McGlynn December 15 1998.
Add MRD_NSTRUCT since IDL has mysterious problems compiling
very large structures.
Removed TEMPDIR and OLD_STRUCT keywords W. Landsman October 2003
Alternate pathway without EXECUTE for V6.0 virtual machine, D. Lindler
Removed limit on EXECUTE statement. W. Landsman October 2003
Restore EXECUTE limit (sigh...), added NO_EXECUTE keyword
W. Landsman July 2004
Fix use of STRUCTYP with /NO_EXECUTE W. Landsman June 2005
Assume since V6.0 (lmgr function available), remove 131 string length
limit for execute W. Landsman Jun 2009
Restore EXECUTE limit (sigh...) W. Landsman July 2009
Make sure "0" is a short integer even with compile_opt idl2 July 2010
Added "0.0", "0.0d", "0u", "0ul", and "0ull" as valid tags
for /NO_EXECUTE E. Rykoff May 2012
(See astrolib/pro/mrd_struct.pro)
MULTINOM
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NAME:
MULTINOM
PURPOSE:
SIMULATE MULTINOMIAL RANDOM VARIABLES
AUTHOR : BRANDON C. KELLY, STEWARD OBS., APR 2006
INPUTS :
N - THE NUMBER OF TRIALS
P - A K-ELEMENT VECTOR CONTAINING THE PROBABILITIES FOR EACH
CLASS.
OPTIONAL INPUTS :
NRAND - THE NUMBER OF RANDOM VARIABLES TO DRAW
SEED - THE SEED FOR THE RANDOM NUMBER GENERATOR
OUTPUT :
NRAND RANDOM DRAWS FROM A MULTINOMIAL DISTRIBUTION WITH PARAMETERS
N AND P.
(See astrolib/pro/multinom.pro)
MULTIPLOT
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Name:
MULTIPLOT
Purpose:
Create multiple plots with simple control over the gaps between plots.
By default, the gap is zero but this can be set with the
gap= keyword, or xgap=, ygap= for individual control over different axes.
You can also place a single title along the x, y and top axes of the
matrix of plots using the mtitle, mxtitle and mytitle keywords.
It is good for data with one or two shared axes and retains all the
versatility of the plot commands (e.g. all keywords and log scaling).
The plots are connected with the shared axes, which saves space by
omitting redundant ticklabels and titles. Multiplot does this by
setting !p.position, !x.tickname and !y.tickname automatically.
A call (multiplot,/reset) restores original values.
CALLING SEQUENCE:
multiplot, pmulti,
gap=, xgap=, ygap=,
/square,
/doxaxis, /doyaxis,
mTitle=, mTitSize=, mTitOffset=,
mxTitle=, mxTitSize=, mxTitOffset=,
myTitle=, myTitSize=, myTitOffset=,
xtickformat=, ytickformat=
/default, /reset, /rowmajor, /initialize
INPUTS:
pmulti: Optional input. [Nx,Ny] array describing the shape of the
matrix of plots. This is equivalent to the 2nd and 3rd elements
of !p.multi. Or you can send all 5 elements of the !p.multi.
KEYWORD INPUTS:
gap=: Set the gap between plots in normalized units. Default is 0.
This input overrides the xgap and ygap inputs.
xgap=: Gap between plots in the x direction. Default 0. To set both
x and y gap to the same value just use the gap keyword.
ygap=: Gap between plots in the y direction. Default 0. To set both
x and y gap to the same value just use the gap keyword.
mTitle: A single title to go across the top of the matrix of plots,
as opposed to the plot over single plots you generate with the
plot command for example.
mTitSize: The font size of the top title. Default is 1.25*!p.charsize
mTitOffset: Offset of the title in the y-direction.
mxTitle, mxTitSize, mxTitOffset: same as above but for the x-axis title
myTitle, myTitSize, myTitOffset: same as above but for the y-axis title
xtickformat, ytickformat: Set the default tick formats when the ticks
are plotted. This allows the user to avoid sending this to each
plotting command which can have unexpected results if that axis
was not to get tick labels in a given point in the matrix.
KEYWORDS SWITCHES:
/square: Force the axis ratio of each plot to be square. Note if
xgap and ygap are set to different values, this axis ratio will
not be preserved. It will be preserved if gap= is used.
/doxaxis: Put axis labels, etc on the axis. Default is to place labels
only on the left side and bottom sides of the plot matrix, but may
be useful when some cells are empty; for example the x-axis of
a 2x2 grid when only 3 total plots will be created.
/doyaxis: Put axis labels, etc on the yxis. Default is to place labels
only on the left side and bottom sides of the plot matrix, but may
be useful when some cells are empty; for example the x-axis of
a 2x2 grid when only 3 total plots will be created.
/rowmajor: Like setting 5th element of !p.multi to 1.
/reset: Set plotting parameters to their saved values from before
multiplot was initially called.
/default: Set plotting parameters to IDL defaults. This is useful
when the saved parameters get in a whacky state.
/initialize: Just do the initialization. This is what happends when
you first call multiplot anyway.
EXAMPLES:
; Make an array of plots [4,3] with a gap of 0.1 (in norm. coords.)
; and overall titles along the x and y axes as given. Force the
; plots to be square.
cgerase & multiplot, [4,3], /square, gap=0.1, mXtitle='R', mYtitle='F(R)'
for i=0,4*3-1 do begin
cgplot, struct[i].x, struct[i].y, psym=4
multiplot
endfor
multiplot,/reset
Side Effects:
Multiplot sets a number of system variables: !p.position, !p.multi,
!x.tickname, !y.tickname, !P.noerase---but all can be reset with
the call: multiplot,/reset
Things can get out of wack if your program crashes in the middle of
making a matrix of plots, and often /reset will not fix it. In those
cases, calling multiplot,/default will often fix the problem.
Restrictions:
1. If you use !p.multi as the method of telling how many plots
are present, you have to set !p.multi at the beginning each time you
use multiplot or call multiplot with the /reset keyword.
2. There is no way to make plots of different sizes; each plot
covers the same area on the screen or paper.
Modification history:
write, 21-23 Mar 94, Fred Knight ([email protected])
alter plot command that sets !x.window, etc. per suggestion of
Mark Hadfield ([email protected]), 7 Apr 94, FKK
add a /default keyword restore IDL's default values of system vars,
7 Apr 94, FKK
modify two more sys vars !x(y).tickformat to suppress user-formatted
ticknames, per suggestion of Mark Hadfield (qv), 8 Apr 94, FKK
2001-03-20 Added /square keyword
Work in device coordinates so we can force aspect ratio to be square
if requested. Erin Scott Sheldon UMichigan
2007-06-18
Can now place titles on the overall x and y axes, as well as a
top title using these new keywords.
mTitle=, mTitSize=, mTitOffset=,
mxTitle=, mxTitSize=, mxTitOffset=,
myTitle=, myTitSize=, myTitOffset=,
Can also control overall tick formats. Useful because can just call
multiplot initially and set this, while calling on each call to
the plotting program will have unexpected results if the ticks
are not to be labelled for that place in the matrix.
xtickformat, ytickformat
Erin Sheldon, NYU
2007-08-28:
Can now add gaps between the plots with these keywords:
gap=, xgap=, ygap=
where the values are in normalized coordinates. Erin Sheldon, NYU
2009-11-23
Initialize common block if M[X/Y]TITLE set W. Landsman
2011-02-07
Use Coyote Graphics W. Landsman
2012-03-21
Use cgplot on initial call to get right background W.L.
(See astrolib/pro/multiplot.pro)
MWRFITS
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NAME:
MWRFITS
PURPOSE:
Write all standard FITS data types from input arrays or structures.
EXPLANATION:
Must be used with a post-October 2009 version of FXADDPAR.
CALLING SEQUENCE:
MWRFITS, Input, Filename, [Header],
/LSCALE , /ISCALE, /BSCALE,
/USE_COLNUM, /Silent, /Create, /No_comment, /Version, $
Alias=, /ASCII, Separator=, Terminator=, Null=,
/Logical_cols, /Bit_cols, /Nbit_cols,
Group=, Pscale=, Pzero=, Status=
INPUTS:
Input = Array or structure to be written to FITS file.
-When writing FITS primary data or image extensions
input should be an array.
--If data is to be grouped
the Group keyword should be specified to point to
a two dimensional array. The first dimension of the
Group array will be PCOUNT while the second dimension
should be the same as the last dimension of Input.
--If Input is undefined, then a dummy primary dataset
or Image extension is created [This might be done, e.g.,
to put appropriate keywords in a dummy primary
HDU].
-When writing an ASCII table extension, Input should
be a structure array where no element of the structure
is a structure or array (except see below).
--A byte array will be written as A field. No checking
is done to ensure that the values in the byte field
are valid ASCII.
--Complex numbers are written to two columns with '_R' and
'_I' appended to the TTYPE fields (if present). The
complex number is enclosed in square brackets in the output.
--Strings are written to fields with the length adjusted
to accommodate the largest string. Shorter strings are
blank padded to the right.
-When writing a binary table extension, the input should
be a structure array with no element of the structure
being a substructure.
If a structure is specified on input and the output
file does not exist or the /CREATE keyword is specified
a dummy primary HDU is created.
Filename = String containing the name of the file to be written.
By default MWRFITS appends a new extension to existing
files which are assumed to be valid FITS. The /CREATE
keyword can be used to ensure that a new FITS file
is created even if the file already exists.
OUTPUTS:
OPTIONAL INPUTS:
Header = Header should be a string array. Each element of the
array is added as a row in the FITS header. No
parsing is done of this data. MWRFITS will prepend
required structural (and, if specified, scaling)
keywords before the rows specified in Header.
Rows describing columns in the table will be appended
to the contents of Header.
Header lines will be extended or truncated to
80 characters as necessary.
If Header is specified then on return Header will have
the header generated for the specified extension.
OPTIONAL INPUT KEYWORDS:
ALias= Set up aliases to convert from the IDL structure
to the FITS column name. The value should be
a STRARR(2,*) value where the first element of
each pair of values corresponds to a column
in the structure and the second is the name
to be used in the FITS file.
The order of the alias keyword is compatible with
use in MRDFITS.
ASCII - Creates an ASCII table rather than a binary table.
This keyword may be specified as:
/ASCII - Use default formats for columns.
ASCII='format_string' allows the user to specify
the format of various data types such using the following
syntax 'column_type:format, column_type:format'. E.g.,
ASCII='A:A1,I:I6,L:I10,B:I4,F:G15.9,D:G23.17,C:G15.9,M:G23.17'
gives the default formats used for each type. The TFORM
fields for the real and complex types indicate will use corresponding
E and D formats when a G format is specified.
Note that the length of the field for ASCII strings and
byte arrays is automatically determined for each column.
BIT_COLS= An array of indices of the bit columns. The data should
comprise a byte array with the appropriate dimensions.
If the number of bits per row (see NBIT_COLS)
is greater than 8, then the first dimension of the array
should match the number of input bytes per row.
BSCALE Scale floats, longs, or shorts to unsigned bytes (see LSCALE)
/CREATE If this keyword is non-zero, then a new FITS file will
be created regardless of whether the file currently
exists. Otherwise when the file already exists,
a FITS extension will be appended to the existing file
which is assumed to be a valid FITS file.
GROUP= This keyword indicates that GROUPed FITS data is to
be generated.
Group should be a 2-D array of the appropriate output type.
The first dimension will set the number of group parameters.
The second dimension must agree with the last dimension
of the Input array.
ISCALE Scale floats or longs to short integer (see LSCALE)
LOGICAL_COLS= An array of indices of the logical column numbers.
These should start with the first column having index *1*.
The structure element should either be an array of characters
with the values 'T' or 'F', or an array of bytes having the
values byte('T')=84b, byte('F')=70b or 0b. The use of bytes
allows the specification of undefined values (0b).
LSCALE Scale floating point numbers to long integers.
This keyword may be specified in three ways.
/LSCALE (or LSCALE=1) asks for scaling to be automatically
determined. LSCALE=value divides the input by value.
I.e., BSCALE=value, BZERO=0. Numbers out of range are
given the value of NULL if specified, otherwise they are given
the appropriate extremum value. LSCALE=(value,value)
uses the first value as BSCALE and the second as BZERO
(or TSCALE and TZERO for tables).
NBIT_COLS= The number of bits actually used in the bit array.
This argument must point to an array of the same dimension
as BIT_COLS.
NO_TYPES If the NO_TYPES keyword is specified, then no TTYPE
keywords will be created for ASCII and BINARY tables.
No_comment Do not write comment keywords in the header
NULL= Value to be written for integers/strings which are
undefined or unwritable.
PSCALE= An array giving scaling parameters for the group keywords.
It should have the same dimension as the first dimension
of Group.
PZERO= An array giving offset parameters for the group keywords.
It should have the same dimension as the first dimension
of Group.
Separator= This keyword can be specified as a string which will
be used to separate fields in ASCII tables. By default
fields are separated by a blank.
/SILENT Suppress informative messages. Errors will still
be reported.
Terminator= This keyword can be specified to provide a string which
will be placed at the end of each row of an ASCII table.
No terminator is used when not specified.
If a non-string terminator is specified (including
when the /terminator form is used), a new line terminator
is appended.
USE_COLNUM When creating column names for binary and ASCII tables
MWRFITS attempts to use structure field name
values. If USE_COLNUM is specified and non-zero then
column names will be generated as 'C1, C2, ... 'Cn'
for the number of columns in the table.
Version Print the version number of MWRFITS.
OPTIONAL OUTPUT KEYWORD:
Status - 0 if FITS file is successfully written, -1 if there is a
a problem (e.g. nonexistent directory, or no write permission)
EXAMPLE:
Write a simple array:
a=fltarr(20,20)
mwrfits,a,'test.fits'
Append a 3 column, 2 row, binary table extension to file just created.
a={name:'M31', coords:(30., 20.), distance:2}
a=replicate(a, 2);
mwrfits,a,'test.fits'
Now add on an image extension:
a=lonarr(10,10,10)
hdr=("COMMENT This is a comment line to put in the header", $
"MYKEY = "Some desired keyword value")
mwrfits,a,'test.fits',hdr
RESTRICTIONS:
(1) Variable length columns are not supported for anything
other than simple types (byte, int, long, float, double).
(2) Empty strings are converted to 1 element blank strings (because
IDL refuses to write an empty string (0b) from a structure)
NOTES:
This multiple format FITS writer is designed to provide a
single, simple interface to writing all common types of FITS data.
Given the number of options within the program and the
variety of IDL systems available it is likely that a number
of bugs are yet to be uncovered.
PROCEDURES USED:
FXPAR(), FXADDPAR
MODIfICATION HISTORY:
Version 0.9: By T. McGlynn 1997-07-23
Initial beta release.
Dec 1, 1997, Lindler, Modified to work under VMS.
Version 0.91: T. McGlynn 1998-03-09
Fixed problem in handling null primary arrays.
Version 0.92: T. McGlynn 1998-09-09
Add no_comment flag and keep user comments on fields.
Fix handling of bit fields.
Version 0.93: T. McGlynn 1999-03-10
Fix table appends on VMS.
Version 0.93a W. Landsman/D. Schlegel
Update keyword values in chk_and_upd if data type has changed
Version 0.94: T. McGlynn 2000-02-02
Efficient processing of ASCII tables.
Use G rather than E formats as defaults for ASCII tables
and make the default precision long enough that transformations
binary to/from ASCII are invertible.
Some loop indices made long.
Fixed some ends to match block beginnings.
Version 0.95: T. McGlynn 2000-11-06
Several fixes to scaling. Thanks to David Sahnow for
documenting the problems.
Added PCOUNT,GCOUNT keywords to Image extensions.
Version numbers shown in SIMPLE/XTENSION comments
Version 0.96: T. McGlynn 2001-04-06
Changed how files are opened to handle ~ consistently
Version 1.0: T. McGlynn 2001-12-04
Unsigned integers,
64 bit integers.
Aliases
Variable length arrays
Some code cleanup
Version 1.1: T. McGlynn 2002-2-18
Fixed major bug in processing of unsigned integers.
(Thanks to Stephane Beland)
Version 1.2: Stephane Beland 2003-03-17
Fixed problem in creating dummy dataset when passing undefined
data, caused by an update to FXADDPAR routine.
Version 1.2.1 Stephane Beland 2003-09-10
Exit gracefully if write priveleges unavailable
Version 1.3 Wayne Landsman 2003-10-24
Don't use EXECUTE() statement if on a virtual machine
Version 1.3a Wayne Landsman 2004-5-21
Fix for variable type arrays
Version 1.4 Wayne Landsman 2004-07-16
Use STRUCT_ASSIGN when modifying structure with pointer tags
Version 1.4a Wayne Landsman 2005-01-03
Fix writing of empty strings in binary tables
Version 1.4b Wayne Landsman 2006-02-23
Propagate /SILENT keyword to mwr_tablehdr
Version 1.5 Wayne Landsman 2006-05-24
Open file using /SWAP_IF_LITTLE_ENDIAN keyword
Convert empty strings to 1 element blank strings before writing
Version 1.5a Wayne Landsman 2006-06-29
Fix problem introduced 2006-05-24 with multidimensional strings
Version 1.5b K. Tolbert 2006-06-29
Make V1.5a fix work pre-V6.0
Version 1.5c I.Evans/W.Landsman 2006-08-08
Allow logical columns to be specified as bytes
Version 1,5d K. Tolbert 2006-08-11
Make V1.5a fix work for scalar empty string
Version 1.6 W. Landsman 2006-09-22
Assume since V5.5, remove VMS support
Version 1.6a W. Landsman 2006-09-22
Don't right-justify strings
Version 1.7 W. Landsman 2009-01-12
Added STATUS output keyword
Version 1.7a W. Landsman 2009-04-10
Since V6.4 strings are no longer limited to 1024
elements
Version 1.8 Pierre Chanial 2009-06-23
trim alias, implement logical TFORM 'L', don't
add space after tform key.
Version 1.9 W. Landsman 2009-07-20
Suppress compilation messages of supporting routines
Version 1.10 W. Landsman 2009-09-30
Allow TTYPE values of 'T' and 'F', fix USE_COLNUM for bin tables
Version 1.11 W. Landsman 2010-11-18
Allow LONG64 number of bytes, use V6.0 notation
Version 1.11a W. Landsman 2012-08-12
Better documentation, error checking for logical columns
Version 1.11b M. Haffner/W.L. 2012-10-12
(See astrolib/pro/mwrfits.pro)
NGP
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NAME:
NGP
PURPOSE:
Interpolate an irregularly sampled field using Nearest Grid Point
EXPLANATION:
This function interpolates irregularly gridded points to a
regular grid using Nearest Grid Point.
CATEGORY:
Mathematical functions, Interpolation
CALLING SEQUENCE:
Result = NGP, VALUE, POSX, NX[, POSY, NY, POSZ, NZ,
/AVERAGE, /WRAPAROUND, /NO_MESSAGE]
INPUTS:
VALUE: Array of sample weights (field values). For e.g. a
temperature field this would be the temperature and the
keyword AVERAGE should be set. For e.g. a density field
this could be either the particle mass (AVERAGE should
not be set) or the density (AVERAGE should be set).
POSX: Array of X coordinates of field samples, unit indices: [0,NX>.
NX: Desired number of grid points in X-direction.
OPTIONAL INPUTS:
POSY: Array of Y coordinates of field samples, unit indices: [0,NY>.
NY: Desired number of grid points in Y-direction.
POSZ: Array of Z coordinates of field samples, unit indices: [0,NZ>.
NZ: Desired number of grid points in Z-direction.
KEYWORD PARAMETERS:
AVERAGE: Set this keyword if the nodes contain field samples
(e.g. a temperature field). The value at each grid
point will then be the average of all the samples
allocated to it. If this keyword is not set, the
value at each grid point will be the sum of all the
nodes allocated to it (e.g. for a density field from
a distribution of particles). (D=0).
WRAPAROUND: Set this keyword if the data is periodic and if you
want the first grid point to contain samples of both
sides of the volume (see below). (D=0).
NO_MESSAGE: Suppress informational messages.
Example of default NGP allocation: n0=4, *=gridpoint.
0 1 2 3 Index of gridpoints
* * * * Grid points
|---|---|---|---| Range allocated to gridpoints ([0.0,1.0> --> 0, etc.)
0 1 2 3 4 posx
Example of NGP allocation for WRAPAROUND: n0=4, *=gridpoint.
0 1 2 3 Index of gridpoints
* * * * Grid points
|---|---|---|---|-- Range allocated to gridpoints ([0.5,1.5> --> 1, etc.)
0 1 2 3 4=0 posx
OUTPUTS:
Prints that a NGP interpolation is being performed of x
samples to y grid points, unless NO_MESSAGE is set.
RESTRICTIONS:
All input arrays must have the same dimensions.
Postition coordinates should be in `index units' of the
desired grid: POSX=[0,NX>, etc.
PROCEDURE:
Nearest grid point is determined for each sample.
Samples are allocated to nearest grid points.
Grid point values are computed (sum or average of samples).
EXAMPLE:
nx = 20
ny = 10
posx = randomu(s,1000)
posy = randomu(s,1000)
value = posx^2+posy^2
field = ngp(value,posx*nx,nx,posy*ny,ny,/average)
surface,field,/lego
NOTES:
Use tsc.pro or cic.pro for a higher order interpolation schemes. A
standard reference for these interpolation methods is: R.W. Hockney
and J.W. Eastwood, Computer Simulations Using Particles (New York:
McGraw-Hill, 1981).
MODIFICATION HISTORY:
Written by Joop Schaye, Feb 1999.
Check for LONG overflow P. Riley/W. Landsman December 1999
(See astrolib/pro/ngp.pro)
NINT
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NAME:
NINT
PURPOSE:
Nearest integer function.
EXPLANATION:
NINT() is similar to the intrinsic ROUND function, with the following
two differences:
(1) if no absolute value exceeds 32767, then the array is returned as
as a type INTEGER instead of LONG
(2) NINT will work on strings, e.g. print,nint(['3.4','-0.9']) will
give [3,-1], whereas ROUND() gives an error message
CALLING SEQUENCE:
result = nint( x, [ /LONG] )
INPUT:
X - An IDL variable, scalar or vector, usually floating or double
Unless the LONG keyword is set, X must be between -32767.5 and
32767.5 to avoid integer overflow
OUTPUT
RESULT - Nearest integer to X
OPTIONAL KEYWORD INPUT:
LONG - If this keyword is set and non-zero, then the result of NINT
is of type LONG. Otherwise, the result is of type LONG if
any absolute values exceed 32767, and type INTEGER if all
all absolute values are less than 32767.
EXAMPLE:
If X = [-0.9,-0.1,0.1,0.9] then NINT(X) = [-1,0,0,1]
PROCEDURE CALL:
None:
REVISION HISTORY:
Written W. Landsman January 1989
Added LONG keyword November 1991
Use ROUND if since V3.1.0 June 1993
Always start with ROUND function April 1995
Return LONG values, if some input value exceed 32767
and accept string values February 1998
Use size(/TNAME) instead of DATATYPE() October 2001
(See astrolib/pro/nint.pro)
NSTAR
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NAME:
NSTAR
PURPOSE:
Simultaneous point spread function fitting (adapted from DAOPHOT)
EXPLANATION:
This PSF fitting algorithm is based on a very old (~1987) version of
DAOPHOT, and much better algorithms (e.g. ALLSTAR) are now available
-- though not in IDL.
CALLING SEQUENCE:
NSTAR, image, id, xc, yc, mags, sky, group, [ phpadu, readns, psfname,
magerr, iter, chisq, peak, /PRINT , /SILENT, /VARSKY, /DEBUG ]
INPUTS:
image - image array
id - vector of stellar ID numbers given by FIND
xc - vector containing X position centroids of stars (e.g. as found
by FIND)
yc - vector of Y position centroids
mags - vector of aperture magnitudes (e.g. as found by APER)
If 9 or more parameters are supplied then, upon output
ID,XC,YC, and MAGS will be modified to contain the new
values of these parameters as determined by NSTAR.
Note that the number of output stars may be less than
the number of input stars since stars may converge, or
"disappear" because they are too faint.
sky - vector of sky background values (e.g. as found by APER)
group - vector containing group id's of stars as found by GROUP
OPTIONAL INPUT:
phpadu - numeric scalar giving number of photons per digital unit.
Needed for computing Poisson error statistics.
readns - readout noise per pixel, numeric scalar. If not supplied,
NSTAR will try to read the values of READNS and PHPADU from
the PSF header. If still not found, user will be prompted.
psfname - name of FITS image file containing the point spread
function residuals as determined by GETPSF, scalar string.
If omitted, then NSTAR will prompt for this parameter.
OPTIONAL OUTPUTS:
MAGERR - vector of errors in the magnitudes found by NSTAR
ITER - vector containing the number of iterations required for
each output star.
CHISQ- vector containing the chi square of the PSF fit for each
output star.
PEAK - vector containing the difference of the mean residual of
the pixels in the outer half of the fitting circle and
the mean residual of pixels in the inner half of the
fitting circle
OPTIONAL KEYWORD INPUTS:
/SILENT - if set and non-zero, then NSTAR will not display its results
at the terminal
/PRINT - if set and non-zero then NSTAR will also write its results to
a file nstar.prt. One also can specify the output file name
by setting PRINT = 'filename'.
/VARSKY - if this keyword is set and non-zero, then the sky level of
each group is set as a free parameter.
/DEBUG - if this keyword is set and non-zero, then the result of each
fitting iteration will be displayed.
PROCEDURES USED:
DAO_VALUE(), READFITS(), REMOVE, SPEC_DIR(), STRN(), SXPAR()
COMMON BLOCK:
RINTER - contains pre-tabulated values for cubic interpolation
REVISION HISTORY
W. Landsman ST Systems Co. May, 1988
Adapted for IDL Version 2, J. Isensee, September, 1990
Minor fixes so that PRINT='filename' really prints to 'filename', and
it really silent if SILENT is set. J.Wm.Parker HSTX 1995-Oct-31
Added /VARSKY option W. Landsman HSTX May 1996
Converted to IDL V5.0 W. Landsman September 1997
Replace DATATYPE() with size(/TNAME) W. Landsman November 2001
Assume since V5.5, remove VMS calls W. Landsman September 2006
(See astrolib/pro/nstar.pro)
NULLTRIM
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NAME:
NULLTRIM
PURPOSE:
Trim a string of all characters after and including the first null
EXPLANATION:
The null character is an ascii 0b
CALLING SEQUENCE:
result = nulltrim( st )
INPUTS:
st = input string
OUTPUTS:
trimmed string returned as the function value.
HISTORY:
D. Lindler July, 1987
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/nulltrim.pro)
NUTATE
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NAME:
NUTATE
PURPOSE:
Return the nutation in longitude and obliquity for a given Julian date
CALLING SEQUENCE:
NUTATE, jd, Nut_long, Nut_obliq
INPUT:
jd - Julian ephemeris date, scalar or vector, double precision
OUTPUT:
Nut_long - the nutation in longitude, same # of elements as jd
Nut_obliq - nutation in latitude, same # of elements as jd
EXAMPLE:
(1) Find the nutation in longitude and obliquity 1987 on Apr 10 at Oh.
This is example 22.a from Meeus
IDL> jdcnv,1987,4,10,0,jul
IDL> nutate, jul, nut_long, nut_obliq
==> nut_long = -3.788 nut_obliq = 9.443
(2) Plot the large-scale variation of the nutation in longitude
during the 20th century
IDL> yr = 1900 + indgen(100) ;Compute once a year
IDL> jdcnv,yr,1,1,0,jul ;Find Julian date of first day of year
IDL> nutate,jul, nut_long ;Nutation in longitude
IDL> plot, yr, nut_long
This plot will reveal the dominant (18.6 year) period, but a finer
grid is needed to display the shorter periods in the nutation.
METHOD:
Uses the formula in Chapter 22 of ``Astronomical Algorithms'' by Jean
Meeus (1998, 2nd ed.) which is based on the 1980 IAU Theory of Nutation
and includes all terms larger than 0.0003".
PROCEDURES CALLED:
POLY() (from IDL User's Library)
CIRRANGE, ISARRAY() (from IDL Astronomy Library)
REVISION HISTORY:
Written, W.Landsman (Goddard/HSTX) June 1996
Converted to IDL V5.0 W. Landsman September 1997
Corrected minor typos in values of d_lng W. Landsman December 2000
Updated typo in cdelt term December 2000
Avoid overflow for more than 32767 input dates W. Landsman January 2005
(See astrolib/pro/nutate.pro)
N_BYTES()
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NAME:
N_bytes()
PURPOSE:
To return the total number of bytes in data element
CALLING SEQUENCE:
result = N_bytes(a)
INPUTS:
a - any idl data element, scalar or array
OUTPUTS:
total number of bytes in a is returned as the function value
(64bit longword scalar)
NOTES:
(1) Not valid for object or pointer data types
(2) For a string array, the number of bytes is computed after conversion
with the BYTE() function, i.e. each element has the same length,
equal to the maximum individual string length.
MODIFICATION HISTORY:
Version 1 By D. Lindler Oct. 1986
Include new IDL data types W. Landsman June 2001
Now return a 64bit integer W. Landsman April 2006
(See astrolib/pro/n_bytes.pro)
OBSERVATORY
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NAME:
OBSERVATORY
PURPOSE:
Return longitude, latitude, altitude & time zones of an observatory
EXPLANATION:
Given an observatory name, returns a structure giving the longitude,
latitude, altitude, and time zone
CALLING SEQUENCE:
Observatory, obsname, obs_struct, [ /PRINT ]
INPUTS:
obsname - scalar or vector string giving abbreviated name(s) of
observatories for which location or time information is requested.
If obsname is an empty string, then information is returned for
all observatories in the database. See the NOTES: section
for the list of 41 recognized observatories. The case of the
string does not matter
OUTPUTS:
obs_struct - an IDL structure containing information on the specified
observatories. The structure tags are as follows:
.observatory - abbreviated observatory name
.name - full observatory name
.longitude - observatory longitude in degrees *west*
.latitude - observatory latitude in degrees
.altitude - observatory altitude in meters above sea level
.tz - time zone, number of hours *west* of Greenwich
OPTIONAL INPUT KEYWORD:
/PRINT - If this keyword is set, (or if only 1 parameter is supplied)
then OBSERVATORY will display information about the specified
observatories at the terminal
EXAMPLE:
Get the latitude, longitude and altitude of Kitt Peak National Observatory
IDL> observatory,'kpno',obs
IDL> print,obs.longitude ==> 111.6 degrees west
IDL> print,obs.latitude ==> +31.9633 degrees
IDL> print,obs.altitude ==> 2120 meters above sea level
NOTES:
Observatory information is taken from noao$lib/obsdb.dat file in IRAF 2.11
Currently recognized observatory names are as follows:
'kpno': Kitt Peak National Observatory
'ctio': Cerro Tololo Interamerican Observatory
'eso': European Southern Observatory
'lick': Lick Observatory
'mmto': MMT Observatory
'cfht': Canada-France-Hawaii Telescope
'lapalma': Roque de los Muchachos, La Palma
'mso': Mt. Stromlo Observatory
'sso': Siding Spring Observatory
'aao': Anglo-Australian Observatory
'mcdonald': McDonald Observatory
'lco': Las Campanas Observatory
'mtbigelow': Catalina Observatory: 61 inch telescope
'dao': Dominion Astrophysical Observatory
'spm': Observatorio Astronomico Nacional, San Pedro Martir
'tona': Observatorio Astronomico Nacional, Tonantzintla
'Palomar': The Hale Telescope
'mdm': Michigan-Dartmouth-MIT Observatory
'NOV': National Observatory of Venezuela
'bmo': Black Moshannon Observatory
'BAO': Beijing XingLong Observatory
'keck': W. M. Keck Observatory
'ekar': Mt. Ekar 182 cm. Telescope
'apo': Apache Point Observatory
'lowell': Lowell Observatory
'vbo': Vainu Bappu Observatory
'flwo': Whipple Observatory
'oro': Oak Ridge Observatory
'lna': Laboratorio Nacional de Astrofisica - Brazil
'saao': South African Astronomical Observatory
'casleo': Complejo Astronomico El Leoncito, San Juan
'bosque': Estacion Astrofisica Bosque Alegre, Cordoba
'rozhen': National Astronomical Observatory Rozhen - Bulgaria
'irtf': NASA Infrared Telescope Facility
'bgsuo': Bowling Green State Univ Observatory
'ca': Calar Alto Observatory
'holi': Observatorium Hoher List (Universitaet Bonn) - Germany
'lmo': Leander McCormick Observatory
'fmo': Fan Mountain Observatory
'whitin': Whitin Observatory, Wellesley College
'mgio': Mount Graham International Observatory
PROCEDURE CALLS:
TEN()
REVISION HISTORY:
Written W. Landsman July 2000
Corrected sign error for 'holi' W.L/ Holger Israel Mar 2008
Correctly terminate when observatory name not recognized
S. Koposov, July 2008
(See astrolib/pro/observatory.pro)
ONE_ARROW
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NAME:
ONE_ARROW
PURPOSE:
Draws an arrow labeled with a single character on the current device
EXPLANATION:
ONE_ARROW is called, for example, by ARROWS to create a
"weathervane" showing the N-E orientation of an image.
CALLING SEQUENCE:
one_arrow, xcen, ycen, angle, label, CHARSIZE = , THICK = , COLOR =
ARROWSIZE=, FONT = ]
INPUT PARAMETERS:
xcen, ycen = starting point of arrow, floating point scalars,
In device coordinates unless /DATA or /NORMAL set
angle = angle of arrow in degrees counterclockwise from +X direction
label = single-character label (may be blank)
OUTPUT PARAMETERS: none
OPTIONAL INPUT PARAMETERS:
ARROWSIZE = 3-element vector defining appearance of arrow.
For device coordinates the default is [30.0, 9.0, 35.0],
meaning arrow is 30 pixels long; arrowhead lines 9 pixels
long and inclined 35 degrees from arrow shaft. For
normalized coordinates the default is divided by 512., for
data coordinates the default is multiplied by
(!X.crange[1] - !X.crange[0])/512..
CHARSIZE = usual IDL meaning, default = 2.0
COLOR = name or number give the color to draw the arrow. See
cgCOLOR for a list of color names.
/DATA - If set, then the input position (xcen, ycen) and the ARROWSIZE
lengths are interpreted as being in data coordinates
FONT - IDL vector font number to use (1-20). For example, to write
the 'N' and 'E' characters in complex script, set font=13
/NORMAL - If set, then the input position (xcen, ycen) and the ARROWSIZE
lengths are interpreted as being in normal coordinates
THICK = usual IDL meaning, default = 2.0
EXAMPLE:
Draw an triple size arrow emanating from the point (212,224)
and labeled with the character 'S'
IDL> one_arrow,212,224,270,'S',charsize=3
PROCEDURE:
Calls one_ray to vector-draw arrow.
MODIFICATION HISTORY:
Written by R. S. Hill, Hughes STX Corp., 20-May-1992.
Added font keyword, W.B. Landsman Hughes STX Corp. April 1995
Modified to work correctly for COLOR=0 J.Wm.Parker, HITC 1995 May 25
Add /NORMAL and /DATA keywords W.Landsman November 2006
Work with Coyote graphics W. Landsman February 2011
(See astrolib/pro/one_arrow.pro)
ONE_RAY
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NAME:
ONE_RAY
PURPOSE:
Draw a line with a specified starting point, length, and angle
CALLING SEQUENCE:
one_ray, xcen, ycen, len, angle, terminus, /NODRAW ]
INPUT PARAMETERS:
xcen, ycen = starting point in device coordinates, floating point
scalars
len = length in pixels, device coordinates
angle = angle in degrees counterclockwise from +X direction
OUTPUT PARAMETERS:
terminus = two-element vector giving ending point of ray in device
coordinates
OPTIONAL KEYWORD INPUT PARAMETERS:
/nodraw if non-zero, the ray is not actually drawn, but the terminus
is still calculated
Any valid keyword to cgPLOTS can also be passed ot ONE_RAY. In
particular, COLOR, THICK, and LINESTYLE control the color, thickness
and linestyle of the drawn line.
EXAMPLE:
Draw a double thickness line of length 32 pixels from (256,256)
45 degrees counterclockwise from the X axis
IDL> one_ray, 256, 256, 32, 45 ,term, THICK = 2
PROCEDURE: straightforward matrix arithmetic
MODIFICATION HISTORY:
Written by R. S. Hill, Hughes STX Corp., 20-May-1992.
Modified to work correctly for COLOR=0 J.Wm.Parker HITC 1995 May 25
Added _EXTRA keywords to PLOT W. Landsman November 2006
Work with Coyote Graphcis W. Landsman February 2011
(See astrolib/pro/one_ray.pro)
OPLOTERROR
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NAME:
OPLOTERROR
PURPOSE:
Over-plot data points with accompanying X or Y error bars.
EXPLANATION:
For use instead of PLOTERROR when the plotting system has already been
defined.
CALLING SEQUENCE:
oploterror, [ x,] y, [xerr], yerr,
[ /NOHAT, HATLENGTH= , ERRTHICK =, ERRSTYLE=, ERRCOLOR =,
/LOBAR, /HIBAR, NSKIP = , NSUM = , /ADDCMD, ... OPLOT keywords ]
INPUTS:
X = array of abcissae, any datatype except string
Y = array of Y values, any datatype except string
XERR = array of error bar values (along X)
YERR = array of error bar values (along Y)
OPTIONAL INPUT KEYWORD PARAMETERS:
/ADDCMD = Set this keyword if you want to add this command to
a cgWindow.
/NOHAT = if specified and non-zero, the error bars are drawn
without hats.
HATLENGTH = the length of the hat lines used to cap the error bars.
Defaults to !D.X_VSIZE / 100).
ERRTHICK = the thickness of the error bar lines. Defaults to the
THICK plotting keyword.
ERRSTYLE = the line style to use when drawing the error bars. Uses
the same codes as LINESTYLE.
ERRCOLOR = String (e.g. 'red') or scalar integer (0 - !D.N_TABLE)
specifying the color to use for the error bars. See CGCOLOR()
for a list of possible color names. See
http://www.idlcoyote.com/cg_tips/legcolor.php
for a warning about the use of indexed color
NSKIP = Positive Integer specifying the error bars to be plotted.
For example, if NSKIP = 2 then every other error bar is
plotted; if NSKIP=3 then every third error bar is plotted.
Default is to plot every error bar (NSKIP = 1)
NSUM = Number of points to average over before plotting, default =
!P.NSUM The errors are also averaged, and then divided by
sqrt(NSUM). This approximation is meaningful only when the
neighboring error bars have similar sizes.
/LOBAR = if specified and non-zero, will draw only the -ERR error bars.
/HIBAR = if specified and non-zero, will draw only the +ERR error bars.
If neither LOBAR or HIBAR are set _or_ if both are set,
you will get both error bars. Just specify one if you
only want one set.
Any valid keywords to the OPLOT command (e.g. PSYM, YRANGE) are also
accepted by OPLOTERROR via the _EXTRA facility.
NOTES:
If only two parameters are input, they are taken as Y and YERR. If only
three parameters are input, they will be taken as X, Y and YERR,
respectively.
EXAMPLE:
Suppose one has X and Y vectors with associated errors XERR and YERR
and that a plotting system has already been defined:
(1) Overplot Y vs. X with both X and Y errors and no lines connecting
the points
IDL> oploterror, x, y, xerr, yerr, psym=3
(2) Like (1) but overplot only the Y errors bars and omits "hats"
IDL> oploterror, x, y, yerr, psym=3, /NOHAT
(3) Like (2) but suppose one has a positive error vector YERR1, and
a negative error vector YERR2 (asymmetric error bars)
IDL> oploterror, x, y, yerr1, psym=3, /NOHAT,/HIBAR
IDL> oploterror, x, y, yerr2, psym=3, /NOHAT,/LOBAR
PROCEDURE:
A plot of X versus Y with error bars drawn from Y - YERR to Y + YERR
and optionally from X - XERR to X + XERR is written to the output device
WARNING:
This an enhanced version of the procedure OPLOTERR in the standard RSI
library. It was renamed to OPLOTERROR in June 1998 in the IDL
Astronomy library.
MODIFICATION HISTORY:
Adapted from the most recent version of PLOTERR. M. R. Greason,
Hughes STX, 11 August 1992.
Added COLOR keyword option to error bars W. Landsman November 1993
Add ERRCOLOR, use _EXTRA keyword, W. Landsman, July 1995
Remove spurious call to PLOT_KEYWORDS W. Landsman, August 1995
OPLOT more than 32767 error bars W. Landsman, Feb 1996
Added NSKIP keyword W. Landsman, Dec 1996
Added HIBAR and LOBAR keywords, M. Buie, Lowell Obs., Feb 1998
Rename to OPLOTERROR W. Landsman June 1998
Ignore !P.PSYM when drawing error bars W. Landsman Jan 1999
Handle NSUM keyword correctly W. Landsman Aug 1999
Check limits for logarithmic axes W. Landsman Nov. 1999
Work in the presence of NAN values W. Landsman Dec 2000
Improve logic when NSUM or !P.NSUM is set W. Landsman Jan 2001
Remove NSUM keyword from PLOTS call W. Landsman March 2001
Only draw error bars with in XRANGE (for speed) W. Landsman Jan 2002
Fix Jan 2002 update to work with log plots W. Landsman Jun 2002
Added STRICT_EXTRA keyword W. Landsman July 2005
W. Landsman Fixed case of logarithmic axes reversed Mar 2009
Update for Coyote Graphics W. Landsman Feb. 2011
Hats were not being plotted by default W. Landsman Apr 2011
With latest CGPLOT, no need to deal special case of only a single point
W. Landsman October 2012
(See astrolib/pro/oploterror.pro)
ORDINAL
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NAME:
ORDINAL
PURPOSE:
Convert an integer to a correct English ordinal string:
EXPLANATION:
The first four ordinal strings are "1st", "2nd", "3rd", "4th" ....
CALLING SEQUENCE:
result = ordinal( num )
INPUT PARAMETERS:
num = number to be made an ordinal. If float, will be FIXed.
OUTPUT PARAMETERS:
result = string such as '1st' '3rd' '164th' '87th', etc.
MODIFICATION HISTORY:
Written by R. S. Hill, STX, 8 Aug. 1991
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/ordinal.pro)
PARTVELVEC
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NAME:
PARTVELVEC
PURPOSE:
Plot the velocity vectors of particles at their positions
EXPLANATION:
This procedure plots the velocity vectors of particles (at the
positions of the particles).
CATEGORY:
Plotting, Two-dimensional.
CALLING SEQUENCE:
PARTVELVEC, VELX, VELY, POSX, POSY [, X, Y]
INPUTS:
VELX: An array of any dimension, containing the x-components
of the particle velocities.
VELY: An array of the same dimension as velx, containing the
y-components of the particle velocities.
POSX: An array of the same dimension as velx, containing the
x-components of the particle positions.
POSY: An array of the same dimension as velx, containing the
y-components of the particle positions.
OPTIONAL INPUTS:
X: Optional abcissae values. X must be a vector.
Y: Optional ordinate values. Y must be a vector. If only X
is specified, then Y is taken equal to be equal to X.
OPTIONAL INPUT KEYWORD PARAMETERS:
FRACTION: The fraction of the vectors to plot. They are
taken at random from the complete sample. Default is
FRACTION = 1.0, use all vectors
LENGTH: The maximum vectorlength relative to the plot data
window. Default = 0.08
COLOR: Color for the vectors, axes and titles by string name or
number (see cgCOLOR). Note that if VECCOLORS is
supplied, then the COLOR keyword still specifies the
color of the axes and title. Default = 'Opposite'
OVER: Plot over the previous plot
VECCOLORS: The vector colors. Must be either a scalar, or
a vector (nmeric or string) the same size as VELX.
Set to COLOR by default.
WINDOW - Set this keyword to plot to a resizeable graphics window
Plot All other keywords available to cgPlot (e.g. AXISCOLOR,
Keywords: LINESTYLE, XRANGE) are available (via _EXTRA)
OUTPUTS:
This procedure plots the velocity vectors (VELX,VELY) at the
positions of the particles, (POSX,POSY). If X and Y are not
specified, then the size of the plot is such that all vectors
just fit within in the plot data window.
SIDE EFFECTS:
Plotting on the current device is performed.
EXAMPLE:
Generate some particle positions and velocities.
POSX=RANDOMU(seed,200)
POSY=RANDOMU(seed,200)
VELX=RANDOMU(seed,200)-0.5
VELY=RANDOMU(seed,200)-0.5
Plot the particle velocities.
PARTVELVEC, VELX, VELY, POSX, POSY
Example using vector colors.
POSX=RANDOMU(seed,200)
POSY=RANDOMU(seed,200)
VELX=RANDOMU(seed,200)-0.5
VELY=RANDOMU(seed,200)-0.5
magnitude = SQRT(velx^2 + vely^2)
LOADCT, 5, NCOLORS=254, BOTTOM=1 ; Load vector colors
colors = BytScl(magnitude, Top=254) + 1B
PARTVELVEC, VELX, VELY, POSX, POSY, COLOR='green', VECCOLORS=colors
MODIFICATION HISTORY:
Written by: Joop Schaye ([email protected]), Sep 1996.
Added /OVER keyword Theo Brauers ([email protected]) Jul 2002
Added VECCOLORS keyword. David Fanning ([email protected]) March, 2005
Incorporate the Coyote Graphics (cg) plot programs WL January 2011
(See astrolib/pro/partvelvec.pro)
PCA
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NAME:
PCA
PURPOSE:
Carry out a Principal Components Analysis (Karhunen-Loeve Transform)
EXPLANATION:
Results can be directed to the screen, a file, or output variables
See notes below for comparison with the intrinsic IDL function PCOMP.
CALLING SEQUENCE:
PCA, data, eigenval, eigenvect, percentages, proj_obj, proj_atr,
[MATRIX =, TEXTOUT = ,/COVARIANCE, /SSQ, /SILENT ]
INPUT PARAMETERS:
data - 2-d data matrix, data(i,j) contains the jth attribute value
for the ith object in the sample. If N_OBJ is the total
number of objects (rows) in the sample, and N_ATTRIB is the
total number of attributes (columns) then data should be
dimensioned N_OBJ x N_ATTRIB.
OPTIONAL INPUT KEYWORD PARAMETERS:
/COVARIANCE - if this keyword is set, then the PCA will be carried out
on the covariance matrix (rare), the default is to use the
correlation matrix
/SILENT - If this keyword is set, then no output is printed
/SSQ - if this keyword is set, then the PCA will be carried out on
on the sums-of-squares & cross-products matrix (rare)
TEXTOUT - Controls print output device, defaults to !TEXTOUT
textout=1 TERMINAL using /more option
textout=2 TERMINAL without /more option
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file
textout = filename (default extension of .prt)
OPTIONAL OUTPUT PARAMETERS:
eigenval - N_ATTRIB element vector containing the sorted eigenvalues
eigenvect - N_ATRRIB x N_ATTRIB matrix containing the corresponding
eigenvectors
percentages - N_ATTRIB element containing the cumulative percentage
variances associated with the principal components
proj_obj - N_OBJ by N_ATTRIB matrix containing the projections of the
objects on the principal components
proj_atr - N_ATTRIB by N_ATTRIB matrix containing the projections of
the attributes on the principal components
OPTIONAL OUTPUT PARAMETER
MATRIX = analysed matrix, either the covariance matrix if /COVARIANCE
is set, the "sum of squares and cross-products" matrix if
/SSQ is set, or the (by default) correlation matrix. Matrix
will have dimensions N_ATTRIB x N_ATTRIB
NOTES:
This procedure performs Principal Components Analysis (Karhunen-Loeve
Transform) according to the method described in "Multivariate Data
Analysis" by Murtagh & Heck [Reidel : Dordrecht 1987], pp. 33-48.
See http://astro.u-strasbg.fr/~fmurtagh/mda-sw/
Keywords /COVARIANCE and /SSQ are mutually exclusive.
The printout contains only (at most) the first seven principle
eigenvectors. However, the output variables EIGENVECT contain
all the eigenvectors
Different authors scale the covariance matrix in different ways.
The eigenvalues output by PCA may have to be scaled by 1/N_OBJ or
1/(N_OBJ-1) to agree with other calculations when /COVAR is set.
PCA uses the non-standard system variables !TEXTOUT and !TEXTUNIT.
These can be added to one's session using the procedure ASTROLIB.
The intrinsic IDL function PCOMP duplicates most
most of the functionality of PCA, but uses different conventions and
normalizations. Note the following:
(1) PCOMP requires a N_ATTRIB x N_OBJ input array; this is the transpose
of what PCA expects
(2) PCA uses standardized variables for the correlation matrix: the input
vectors are set to a mean of zero and variance of one and divided by
sqrt(n); use the /STANDARDIZE keyword to PCOMP for a direct comparison.
(3) PCA (unlike PCOMP) normalizes the eigenvectors by the square root
of the eigenvalues.
(4) PCA returns cumulative percentages; the VARIANCES keyword of PCOMP
returns the variance in each variable
(5) PCOMP divides the eigenvalues by (1/N_OBJ-1) when the covariance matrix
is used.
EXAMPLE:
Perform a PCA analysis on the covariance matrix of a data matrix, DATA,
and write the results to a file
IDL> PCA, data, /COVAR, t = 'pca.dat'
Perform a PCA analysis on the correlation matrix. Suppress all
printing, and save the eigenvectors and eigenvalues in output variables
IDL> PCA, data, eigenval, eigenvect, /SILENT
PROCEDURES CALLED:
TEXTOPEN, TEXTCLOSE
REVISION HISTORY:
Immanuel Freedman (after Murtagh F. and Heck A.). December 1993
Wayne Landsman, modified I/O December 1993
Fix MATRIX output, remove GOTO statements W. Landsman August 1998
Changed some index variable to type LONG W. Landsman March 2000
Fix error in computation of proj_atr, see Jan 1990 fix in
http://astro.u-strasbg.fr/~fmurtagh/mda-sw/pca.f W. Landsman Feb 2008
(See astrolib/pro/pca.pro)
PENT
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NAME:
PENT
PURPOSE:
Return the information entropy of a time series
EXPLANATION:
This function will return S, the information entropy of a time series
for a set of trial periods
CATEGORY:
Time series analysis, period finding, astronomical utilities.
CALLING SEQUENCE:
Result = PENT(P, T, X, [N, M ] )
INPUTS:
P - array of trial period values.
T - array of observation times (same units as P).
X - array of observations.
OPTIONAL INPUTS:
N - If four parameters are given then the 4th parameter is assumed
to be N. Then NxN boxes are used to calculate S.
M,N - If five parameters are given then parameter 4 is M and parameter
5 is N. S is then calculated using MxN boxes - M partitions for the
phase and N partitions for the data.
OUTPUTS:
This function returns S, the information entropy of the time series for
the periods given in P as defined by Cincotta, Me'ndez & Nu'n~ez
(Astrophysical Journal 449, 231-235, 1995). The minima of S occur at
values of P where X shows periodicity.
PROCEDURE:
The procedure involves dividing the phase space into N^2 partitions
(NxN boxes) and then calculating:
__ N^2
S = - \ mu_i . ln(mu_i) for all mu_i <> 0
/_
i = 1
where mu_i is the number of data points in partition i normalised by
the number of partitions.
The option of using MxN boxes is an additional feature of this routine.
EXAMPLE:
To generate a similar sythetic data set to Cincotta et al. we
do the following:
IDL> P0 = 173.015 ; Fundamental period
IDL> T = randomu(seed,400)*15000 ; 400 random observation times
IDL> A0 = 14.0 ; Mean magnitude
IDL> M0 = -0.5 * sin(2*!pi*T/P0) ; Fundamental mode
IDL> M1 = -0.15 * sin(4*!pi*T/P0) ; 1st harmonic
IDL> M2 = -0.05 * sin(6*!pi*T/P0) ; 2nd harmonic
IDL> sig = randomu(seed,400)*0.03 ; noise
IDL> U = A0 + M0 + M1 + M2 + sig ; Synthetic data
IDL> Ptest = 100. + findgen(2000)/2. ; Trial periods
IDL> S = pent(Ptest,T,U) ; Calculate S
... this takes a few seconds ...
IDL> plot,Ptest,S,xtitle="P",ytitle="S" ; plot S v. P
IDL> print,Ptest(where(S eq min(S))) ; Print best period (+/- 0.5)
The plot produced should be similar to Fig. 2 of Cincotta et al.
RESTRICTIONS:
My own (limited) experience with this routine suggests that it is not
as good as other techniques for finding weak, multi-periodic signals in
poorly sampled data, but is good for establishing periods of eclipsing
binary stars when M is quite large (try MxN = 64x16, 128x16 or even
256x16). This suggests it may be good for other periodic light curves
(Cepheids, RR Lyrae etc.).
I would be glad to receive reports of other peoples experience with
this technique (e-mail [email protected]).
MODIFICATION HISTORY:
Written by: Pierre Maxted, 14Sep95
Modifications:
Normalisation of S corrected, T-min(T) taken out of loop.
- Pierre Maxted, 15Sep95
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/pent.pro)
PERMUTE
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NAME:
PERMUTE
PURPOSE:
This function returns an array containing the numbers
[0, ..., N-1] in random order. They are useful as indices
when permuting a dataset, for example in a balanced bootstrap
Monte Carlo algorithm.
CATEGORY:
Statistics.
CALLING SEQUENCE:
Result = PERMUTE(N)
INPUTS:
N: The number of items to be permuted.
OPTIONAL INPUTS:
SEED: A random number seed, see RANDOMU.
OUTPUTS:
This function returns an N-element array containing a random
permutation of the integers from 0 through N-1.
SIDE EFFECTS:
Unless Seed is specified, IDL's global random number
seed is changed.
PROCEDURE:
This is an in-place swapping algorithm. It starts with an
index array. For each position in the array, it swaps the
occupant of that position with the occupant of a random
position from there (inclusive) to the end of the array. The
last iteration is not necessary to compute, since it swaps
with itself.
See http://www.techuser.net/randpermgen.html for a proof. The
2-line code there has been optimized for IDL's vector
architecture. This is a linear-time algorithm.
EXAMPLE:
Show some permutations of 6 numbers:
print, permute(6)
0 2 1 3 4 5
print, permute(6)
2 4 3 5 1 0
print, permute(6)
0 4 3 1 2 5
Permute the array [2, 4, 6, 8]
a = [2, 4, 6, 8]
print, a[permute(4)]
4 8 6 2
Test randomness (results should be close to k):
m = 6l
k = 10000l
n = m * k
a = lonarr(m, n)
for i = 0l, n-1, 1 do a[*, i] = permute(m)
for i = 0l, m-1, 1 do print, histogram(a[i, *])
9885 10062 10051 9915 10028 10059
10096 10087 10094 9913 9933 9877
10041 10013 9968 9958 9911 10109
9880 9858 10166 10049 10081 9966
10093 9915 9800 10166 9969 10057
10005 10065 9921 9999 10078 9932
Time the algorithm:
maxn = 7
t = dblarr(maxn)
n = 10L^(indgen(maxn)+1)
for i = 0, maxn-1, 1 do begin &$
t1 = systime(/s) &$
print, n[i] &$
a = permute(n[i]) &$
t2 = systime(/s) &$
t[i] = t2-t1 &$
endfor
print, ' Elements Seconds Elements Per Second'
print, transpose([[n], [t], [t/n]])
Elements Seconds Elements Per Second
10.000000 0.00012397766 1.2397766e-05
100.00000 0.00015020370 1.5020370e-06
1000.0000 0.0011651516 1.1651516e-06
10000.000 0.018178225 1.8178225e-06
100000.00 0.13504505 1.3504505e-06
1000000.0 1.3817160 1.3817160e-06
10000000. 14.609985 1.4609985e-06
These times are for a 2.071 GHz AMD Athlon 2800+ CPU.
MODIFICATION HISTORY:
Written by: Joseph Harrington, Cornell. 2006-03-22
[email protected]
(See astrolib/pro/permute.pro)
PIXCOLOR
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NAME:
PIXCOLOR
PURPOSE:
Assign colors to specified pixel values in a color lookup table
EXPLANATION:
Colors can be specified either from the list in cgcolor
(http://www.idlcoyote.com/programs/cgcolor.pro ) or as 1 letter
abbreviations for 8 common colors.
CALLING SEQUENCE:
PIXCOLOR, pixvalue, color ;Set color at specified pixel values
INPUT PARMETERS:
pixvalue - value or range of pixel values whose color will be modified.
A single pixel value may be specified by an integer
If a range of values is specified, then it must be written
as a string, with a colon denoting the range (e.g.'102:123')
If omitted, program will prompt for this parameter.
OPTIONAL INPUT PARAMETER
color - scalar string specifying either a full color name available in
CGCOLOR, or a single character string giving one of the
specified colors: 'R' (red), 'B' (blue), 'G' (green)
'Y' (yellow), 'T' (turquoise), 'V' (violet), 'W' (white)
or 'D' (dark). If omitted, program will prompt for this
parameter.
OUTPUTS:
None
PROCEDURE:
TVLCT is used in RGB mode to load the specified pixel values.
EXAMPLE:
Set pixel values of 245 to a color of red
IDL> pixcolor,245,'R'
Set pixel values 120 to 150 to Magenta
IDL> pixcolor,'120:150','Magenta'
REVISION HISTORY:
Written, W. Landsman ST Systems Corp. February, 1987
Converted to IDL V5.0 W. Landsman September 1997
Allow specification of cgcolor names April 2011
(See astrolib/pro/pixcolor.pro)
PIXWT
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NAME:
PIXWT
PURPOSE:
Circle-rectangle overlap area computation.
DESCRIPTION:
Compute the fraction of a unit pixel that is interior to a circle.
The circle has a radius r and is centered at (xc, yc). The center of
the unit pixel (length of sides = 1) is at (x, y).
CATEGORY:
CCD data processing
CALLING SEQUENCE:
area = Pixwt( xc, yc, r, x, y )
INPUTS:
xc, yc : Center of the circle, numeric scalars
r : Radius of the circle, numeric scalars
x, y : Center of the unit pixel, numeric scalar or vector
OPTIONAL INPUT PARAMETERS:
None.
KEYWORD PARAMETERS:
None.
OUTPUTS:
Function value: Computed overlap area.
EXAMPLE:
What is the area of overlap of a circle with radius 3.44 units centered
on the point 3.23, 4.22 with the pixel centered at [5,7]
IDL> print,pixwt(3.23,4.22,3.44,5,7) ==> 0.6502
COMMON BLOCKS:
None.
PROCEDURE:
Divides the circle and rectangle into a series of sectors and
triangles. Determines which of nine possible cases for the
overlap applies and sums the areas of the corresponding sectors
and triangles. Called by aper.pro
NOTES:
If improved speed is needed then a C version of this routines, with
notes on how to linkimage it to IDL is available at
ftp://ftp.lowell.edu/pub/buie/idl/custom/
MODIFICATION HISTORY:
Ported by Doug Loucks, Lowell Observatory, 1992 Sep, from the
routine pixwt.c, by Marc Buie.
(See astrolib/pro/pixwt.pro)
PKFIT
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NAME:
PKFIT
PURPOSE:
Subroutine of GETPSF to perform a one-star least-squares fit
EXPLANATION:
Part of the DAOPHOT PSF photometry sequence
CALLING SEQUENCE:
PKFIT, f, scale, x, y, sky, radius, ronois, phpadu, gauss, psf,
errmag, chi, sharp, Niter, /DEBUG
INPUTS:
F - NX by NY array containing actual picture data.
X, Y - the initial estimates of the centroid of the star relative
to the corner (0,0) of the subarray. Upon return, the
final computed values of X and Y will be passed back to the
calling routine.
SKY - the local sky brightness value, as obtained from APER
RADIUS- the fitting radius-- only pixels within RADIUS of the
instantaneous estimate of the star's centroid will be
included in the fit, scalar
RONOIS - readout noise per pixel, scalar
PHPADU - photons per analog digital unit, scalar
GAUSS - vector containing the values of the five parameters defining
the analytic Gaussian which approximates the core of the PSF.
PSF - an NPSF by NPSF look-up table containing corrections from
the Gaussian approximation of the PSF to the true PSF.
INPUT-OUTPUT:
SCALE - the initial estimate of the brightness of the star,
expressed as a fraction of the brightness of the PSF.
Upon return, the final computed value of SCALE will be
passed back to the calling routine.
OUTPUTS:
ERRMAG - the estimated standard error of the value of SCALE
returned by this routine.
CHI - the estimated goodness-of-fit statistic: the ratio
of the observed pixel-to-pixel mean absolute deviation from
the profile fit, to the value expected on the basis of the
noise as determined from Poisson statistics and the
readout noise.
SHARP - a goodness-of-fit statistic describing how much broader
the actual profile of the object appears than the
profile of the PSF.
NITER - the number of iterations the solution required to achieve
convergence. If NITER = 25, the solution did not converge.
If for some reason a singular matrix occurs during the least-
squares solution, this will be flagged by setting NITER = -1.
RESTRICTIONS:
No parameter checking is performed
REVISON HISTORY:
Adapted from the official DAO version of 1985 January 25
Version 2.0 W. Landsman STX November 1988
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/pkfit.pro)
PLANCK()
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NAME:
PLANCK()
PURPOSE:
To calculate the Planck function in units of ergs/cm2/s/A
CALLING SEQUENCE:
bbflux = PLANCK( wave, temp)
INPUT PARAMETERS:
WAVE Scalar or vector giving the wavelength(s) in **Angstroms**
at which the Planck function is to be evaluated.
TEMP Scalar giving the temperature of the planck function in degree K
OUTPUT PARAMETERS:
BBFLUX - Scalar or vector giving the blackbody flux (i.e. !pi*Intensity)
in erg/cm^2/s/A in at the specified wavelength points.
EXAMPLES:
To calculate the blackbody flux at 30,000 K every 100 Angstroms between
2000A and 2900 A
IDL> wave = 2000 + findgen(10)*100
IDL> bbflux = planck(wave,30000)
If a star with a blackbody spectrum has a radius R, and distance,d, then
the flux at Earth in erg/cm^2/s/A will be bbflux*R^2/d^2
PROCEDURE:
The wavelength data are converted to cm, and the Planck function
is calculated for each wavelength point. See Allen (1973), Astrophysical
Quantities, section 44 for more information.
NOTES:
See the procedure planck_radiance.pro in
ftp://origin.ssec.wisc.edu/pub/paulv/idl/Radiance/planck_radiance.pro
for computation of Planck radiance given wavenumber in cm-1 or
wavelength in microns
MODIFICATION HISTORY:
Adapted from the IUE RDAF August, 1989
Converted to IDL V5.0 W. Landsman September 1997
Improve precision of constants W. Landsman January 2002
(See astrolib/pro/planck.pro)
PLANET_COORDS
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NAME:
PLANET_COORDS
PURPOSE:
Find low or high precision RA and DEC for the planets given a date
EXPLANATION:
For low precision this routine uses HELIO to get the heliocentric ecliptic
coordinates of the planets at the given date, then converts these to
geocentric ecliptic coordinates ala "Astronomical Algorithms" by Jean
Meeus (1991, p 209). These are then converted to RA and Dec using EULER.
The accuracy between the years 1800 and 2050 is better than 1 arcminute
for the terrestial planets, but reaches 10 arcminutes for Saturn.
Before 1850 or after 2050 the accuracy can get much worse.
For high precision use the /JPL option ito use the full JPL ephemeris.
CALLING SEQUENCE:
PLANET_COORDS, DATE, RA, DEC, [ PLANET = , /JD, /JPL]
INPUTS:
DATE - If /JD is not set, then date is a 3-6 element vector containing
year,month (1-12), day, and optionally hour, minute, & second.
If /JD is set then DATE is a Julian date. An advantage of the
/JD option is that it allows the use of vector dates.
OUTPUTS:
RA - right ascension of planet(s), J2000 degrees, double precision
DEC - declination of planet(s), J2000 degrees, double precision
OPTIONAL INPUT KEYWORD:
PLANET - scalar string giving name of a planet, e.g. 'venus'. Default
is to compute coords for all of them (except Earth).
/JD - If set, then the date parameter should be supplied as Julian date
JPL - if /JPL set, then PLANET_COORDS will call the procedure
JPLEPHINTERP to compute positions using the full JPL ephemeris.
The JPL ephemeris FITS file JPLEPH.405 must exist in either the
current directory, or in the directory specified by the
environment variable ASTRO_DATA. Alternatively, the JPL keyword
can be set to the full path and name of the ephemeris file.
A copy of the JPL ephemeris FITS file JPLEPH.405 is available in
http://idlastro.gsfc.nasa.gov/ftp/data/
EXAMPLES:
(1) Find the RA, Dec of Venus on 1992 Dec 20
IDL> planet_coords, [1992,12,20], ra,dec ;Compute for all planets
IDL> print,adstring(ra[1],dec[1],1) ;Venus is second planet
====> RA = 21 05 2.66 Dec = -18 51 45.7
This position is 37" from the full DE406 ephemeris position of
RA = 21 05 5.24 -18 51 43.1
(2) Return the current RA and Dec of all 8 planets using JPL ephemeris
IDL> get_juldate, jd ;Get current Julian Date
IDL> planet_coords,jd,ra,dec,/jd,/jpl ;Find positions of all planets
IDL> forprint,adstring(ra,dec,0) ;Display positions
(3) Plot the declination of Mars for every day in the year 2001
IDL> jdcnv,2001,1,1,0,jd ;Get Julian date of midnight on Jan 1
Now get Mars RA,Dec for 365 consecutive days
IDL> planet_coords,jd+indgen(365),ra,dec,/jd, planet = 'mars'
IDL> plot,indgen(365)+1,dec
NOTES:
HELIO is based on the two-body problem and neglects interactions
between the planets. This is why the worst results are for
Saturn. Use the /JPL option or the online ephemeris generator
http://ssd.jpl.nasa.gov/horizons.cgi for more accuracy.
The procedure returns astrometric coordinates, i.e. no correction
for aberration. A correction for light travel time is applied
when /JPL is set, but not for the default low-precision calculation.
PROCEDURES USED:
JULDATE
EULER, HELIO - if /JPL is not set
JPLEPHREAD, JPLEPHINTERP - if /JPL is set
REVISION HISTORY:
Written P.Plait & W. Landsman August 2000
Fixed Julian date conversion W. Landsman August 2000
Added /JPL keyword W. Landsman July 2001
Allow vector Julian dates with JPL ephemeris W. Landsman December 2002
(See astrolib/pro/planet_coords.pro)
PLOTERROR
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NAME:
PLOTERROR
PURPOSE:
Plot data points with accompanying X or Y error bars.
EXPLANATION:
This is a greatly enhanced version of the standard IDL Library routine
PLOTERR
CALLING SEQUENCE:
ploterror, [ x,] y, [xerr], yerr [, TYPE=, /NOHAT, HATLENGTH= , NSUM =
ERRTHICK=, ERRSTYLE=, ErrcolOR=, NSKIP=, .. PLOT keywords]
INPUTS:
X = array of abcissae.
Y = array of Y values.
XERR = array of error bar values (along X)
YERR = array of error bar values (along Y)
OPTIONAL INPUT KEYWORD PARAMETERS:
TYPE = type of plot produced. The possible types are:
TYPE = 0 : X Linear - Y Linear (default)
TYPE = 1 : X Linear - Y Log
TYPE = 2 : X Log - Y Linear
TYPE = 3 : X Log - Y Log
Actually, if 0 is specified, the XLOG and YLOG keywords
are used. If these aren't specified, then a linear-linear
plot is produced. This keyword is available to maintain
compatibility with the previous version of PLOTERROR.
/NOHAT = if specified and non-zero, the error bars are drawn
without hats.
HATLENGTH = the length of the hat lines in device units used to cap the
error bars. Defaults to !D.X_VSIZE / 100).
ERRTHICK = the thickness of the error bar lines. Defaults to the
THICK plotting keyword.
ERRSTYLE = the line style to use when drawing the error bars. Uses
the same codes as LINESTYLE.
ERRCOLOR = String (e.g. 'red') or scalar integer (0 - !D.N_TABLE)
specifying the color to use for the error bars. See CGCOLOR()
for a list of possible color names. See
http://www.idlcoyote.com/cg_tips/legcolor.php
for a warning about the use of indexed color
NSKIP = Integer specifying the error bars to be plotted. For example,
if NSKIP = 2 then every other error bar is plotted; if NSKIP=3
then every third error bar is plotted. Default is to plot
every error bar (NSKIP = 1)
NSUM = Number of points to average over before plotting, default=!P.NSUM
The errors are also averaged, and then divided by sqrt(NSUM).
This approximation is meaningful only when the neighboring error
bars have similar sizes. PLOTERROR does not pass the NSUM
keyword to the PLOT command, but rather computes the binning
itself using the FREBIN function.
TRADITIONAL - If set to 0 then a black plot is drawn on a white background
in the graphcis window. The default value is 1, giving the
traditional black background for a graphics window.
WINDOW - Set this keyword to plot to a resizeable graphics window
Any valid keywords to the cgPLOT command (e.g. PSYM, YRANGE, AXISCOLOR
SYMCOLOR, ASPECT) are also accepted by PLOTERROR via the _EXTRA facility.
RESTRICTIONS:
Arrays must not be of type string, and there must be at least 1 point.
If only three parameters are input, they will be taken as X, Y and
YERR respectively.
PLOTERROR cannot be used for asymmetric error bars. Instead use
OPLOTERROR with the /LOBAR and /HIBAR keywords.
Any data points with NAN values in the X, Y, or error vectors are
ignored.
EXAMPLE:
Suppose one has X and Y vectors with associated errors XERR and YERR
(1) Plot Y vs. X with both X and Y errors and no lines connecting
the points
IDL> ploterror, x, y, xerr, yerr, psym=3
(2) Like (1) but plot only the Y errors bars and omits "hats"
IDL> ploterror, x, y, yerr, psym=3, /NOHAT
WARNING:
This an enhanced version of the procedure PLOTERR in the standard IDL
distribution. It was renamed from PLOTERR to PLOTERROR in June 1998
in the IDL Astronomy Library to avoid conflict with the RSI procedure.
PROCEDURE:
A plot of X versus Y with error bars drawn from Y - YERR to Y + YERR
and optionally from X - XERR to X + XERR is written to the output device
PROCEDURE CALLS:
cgPlot, cgPlots
FREBIN - used to compute binning if NSUM keyword is present
MODIFICATION HISTORY:
William Thompson Applied Research Corporation July, 1986
DMS, April, 1989 Modified for Unix
Michael R. Greason ST Systems
May, 1991 Added most of the plotting keywords, put hats
on the error bars.
K. Venkatakrishna Added option to plot xerr, May, 1992
Michael R. Greason Corrected handling of reversed axes. Aug. 1992
W. Landsman Use _EXTRA keyword July 1995
W. Landsman Plot more than 32767 points Feb 1996
W. Landsman Fix Y scaling when only XRANGE supplied Nov 1996
W. Landsman Added NSKIP keyword Dec 1996
W. Landsman Use XLOG, YLOG instead of XTYPE, YTYPE Jan 1998
W. Landsman Rename to PLOTERROR, OPLOTERROR Jun 1998
W. Landsman Better default scaling when NSKIP supplied Oct 1998
W. Landsman Ignore !P.PSYM when drawing error bars Jan 1999
W. Landsman Handle NSUM keyword correctly Aug 1999
W. Landsman Fix case of /XLOG but no X error bars Oct 1999
W. Landsman Work in the presence of NAN values Nov 2000
W. Landsman Improve logic when NSUM or !P.NSUM is set Jan 2001
W. Landsman Only draw error bars with in XRANGE (for speed) Jan 2002
W. Landsman Fix Jan 2002 update to work with log plots Jun 2002
W. Landsman Added _STRICT_EXTRA Jul 2005
W. Landsman/D.Nidever Fixed case of logarithmic axes reversed Mar 2009
W. Landsman/S. Koch Allow input to be a single point Jan 2010
W. Landsman Add Coyote Graphics Feb 2011
W. Landsman Make keyword name ERRCOLOR instead of ECOLOR
Speedup when no ERRCOLOR defined Feb 2011
D. Fanning Use PLOTS instead of CGPLOTS for speed Jan 2012
(See astrolib/pro/ploterror.pro)
PLOTHIST
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NAME:
PLOTHIST
PURPOSE:
Plot the histogram of an array with the corresponding abcissa.
CALLING SEQUENCE:
plothist, arr, xhist, yhist, [, BIN=, /FILL, /NOPLOT, /OVERPLOT, PEAK=,
/AUTOBIN, ...plotting keywords]
INPUTS:
arr - The array to plot the histogram of. It can include negative
values, but non-integral values will be truncated.
OPTIONAL OUTPUTS:
xhist - X vector used in making the plot
( = lindgen( N_elements(h)) * bin + min(arr) )
yhist - Y vector used in making the plot (= histogram(arr/bin))
OPTIONAL INPUT KEYWORDS:
/AUTOBIN - Automatically determines bin size of the histogram as the
square root of the number of samples. Only valid when BIN
is not set.
AXISCOLOR - Color (string or number) of the plotting axes.
BIN - The size of each bin of the histogram, scalar (not necessarily
integral). If not present (or zero), the bin size is set to 1.
/BOXPLOT - If set, then each histogram data value will be plotted
"box style" with vertical lines drawn from Y=0 at each end of
the bin width
COLOR - Color (number or string) of the plotted data. See CGCOLOR
for a list of available color names.
/HALFBIN - Set this keyword to a nonzero value to shift the binning by
half a bin size. This is useful for integer data, where e.g.
the bin for values of 6 will go from 5.5 to 6.5. The default
is to set the HALFBIN keyword for integer data, and not for
non-integer data.
/NAN - If set, then check for the occurence of IEEE not-a-number values
/NOPLOT - If set, will not plot the result. Useful if intention is to
only get the xhist and yhist outputs.
/OVERPLOT - If set, will overplot the data on the current plot. User
must take care that only keywords valid for OPLOT are used.
PEAK - if non-zero, then the entire histogram is normalized to have
a maximum value equal to the value in PEAK. If PEAK is
negative, the histogram is inverted.
/FILL - if set, will plot a filled (rather than line) histogram.
/ROTATE - if set, the plot is rotated onto it's side, meaning the bars
extend from left to right. Xaxis corresponds to the count within
in each bin. Useful for placing a histogram plot
at the side of a scatter plot, as shown at the bottom of
http://www.dur.ac.uk/j.r.mullaney/pages/software.php
WINDOW - Set this keyword to plot to a resizeable graphics window
The following keywords take effect only if the FILL keyword is set:
FCOLOR - color (string or number) to use for filling the histogram
/FLINE - if set, will use lines rather than solid color for fill (see
the LINE_FILL keyword in the cgcolorfill routine)
FORIENTATION - angle of lines for fill (see the ORIENTATION keyword
in the cgcolorfill routine)
FPATTERN - the pattern to use for the fill (see the PATTERN keyword
in the cgcolorfill routine)
FSPACING - the spacing of the lines to use in the fill (see the SPACING
keyword in the cgcolorfill routine)
FTHICK - the thickness of the lines to use in the fill (see the THICK
keyword in the cgcolorfill routine)
Any input keyword that can be supplied to the cgPLOT procedure (e.g. XRANGE,
AXISCOLOR, LINESTYLE, /XLOG, /YLOG) can also be supplied to PLOTHIST.
EXAMPLE:
(1) Create a vector of random 1000 values derived from a Gaussian of
mean 0, and sigma of 1. Plot the histogram of these values with a
binsize of 0.1, and use a box plotting style.
IDL> a = randomn(seed,1000)
IDL> plothist,a, bin = 0.1, /boxplot
(2) As before, but fill the plot with diagonal lines at a 45 degree
angle
IDL> plothist,a, bin=0.1, /fill, /fline, forient=45
NOTES:
David Fanning has written a similar program HISTOPLOT with more graphics
options: See http://www.idlcoyote.com/programs/histoplot.pro
MODIFICATION HISTORY:
Written W. Landsman January, 1991
Add inherited keywords W. Landsman March, 1994
Use ROUND instead of NINT W. Landsman August, 1995
Add NoPlot and Overplot keywords. J.Wm.Parker July, 1997
Add Peak keyword. J.Wm.Parker Jan, 1998
Add FILL,FCOLOR,FLINE,FPATTERN,FSPACING keywords. J.Wm.Parker Jan, 1998
Add /NAN keyword W. Landsman October 2001
Don't plot out of range with /FILL, added HALFBIN keyword, make
half bin shift default for integer only W. Landsman/J. Kurk May 2002
Add BOXPLOT keyword, use exact XRANGE as default W.L. May 2006
Allow use of /XLOG and /YLOG keywords W.L. June 2006
Adjust Ymin when /YLOG is used W. L. Sep 2007
Added AXISCOLOR keyword, fix color problem with overplots WL Nov 2007
Check when /NAN is used and all elements are NAN S. Koposov Sep 2008
Added /ROTATE keyword to turn plot on its side. J. Mullaney, 2009.
Added FTHICK keyword for thickness of fill lines. L. Anderson Oct. 2010
Use Coyote Graphics W. Landsman Feb 2011
Explicit XSTYLE, YSTYLE keywords to avoid _EXTRA confusion WL. Aug 2011
Fix PLOT keyword problem with /ROTATE WL Dec 2011
(See astrolib/pro/plothist.pro)
PLOTSYM
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NAME:
PLOTSYM
PURPOSE:
Define useful plotting symbols not in the standard !PSYM definitions.
EXPLANATION:
After a symbol has been defined with PLOTSYM, a plotting command should
follow with either PSYM = 8 or !P.PSYM = 8 (see USERSYM)
For additional rotationally symmetric plotting symbols, see VSYM.PRO
Also see CGSYMCAT in the/coyote directory.
CALLING SEQUENCE:
PLOTSYM, PSYM,[ PSIZE, /FILL, THICK=, COLOR=]
INPUTS:
PSYM - The following integer values of PSYM will create the
corresponding plot symbols
0 - circle
1 - downward arrow (upper limit), base of arrow begins at plot value value
2 - upward arrow (lower limt)
3 - 5 pointed star
4 - triangle
5 - upside down triangle
6 - left pointing arrow
7 - right pointing arrow
8 - square
Arrows are defined such that their base begins at their origin.
OPTIONAL INPUTS:
PSIZE - Size of the plotting symbol in multiples of the default size
(default PSIZE=1). Does not need to be an integer
OPTIONAL INPUT KEYWORD:
FILL - Parameter indicating whether to fill the symbol (see USERSYM)
The default is 0, unfilled symbol. Does not affect arrows
or character symbols.
THICK - Thickness of unfilled symbols. Default is 1.
COLOR - Color of the symbols, Default is !P.color
OUTPUTS:
None
EXAMPLES:
Plot Y vs. X with filled stars as the symbol, twice the default size
IDL> PLOTSYM, 3 ,2, /FILL ;Plotting symbol is a filled star,
;twice default size
IDL> PLOT,X,Y,PSYM=8 ;Set PSYM = 8 to get star symbol
Now plot Y vs. X with an open circle as the symbol
IDL> PLOTSYM, 0 ;Plotting symbol is a circle
IDL> PLOT,X,Y,PSYM=8
METHOD:
Appropriate X,Y vectors are used to define the symbol and passed to the
USERSYM command.
REVISION HISTORY
Written W. Landsman June 1992
18-JAN-1996 Added a square symbol, HCW.
98Aug20 Added keyword thick parameter - RCB.
April 2001 Added COLOR keyword WBL
(See astrolib/pro/plotsym.pro)
POIDEV
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NAME:
POIDEV
PURPOSE:
Generate a Poisson random deviate
EXPLANATION:
Return an integer random deviate drawn from a Poisson distribution with
a specified mean. Adapted from procedure of the same name in
"Numerical Recipes" by Press et al. (1992), Section 7.3
NOTE: This routine became partially obsolete in V5.0 with the
introduction of the POISSON keyword to the intrinsic functions
RANDOMU and RANDOMN. However, POIDEV is still useful for adding
Poisson noise to an existing image array, for which the coding is much
simpler than it would be using RANDOMU (see example 1)
CALLING SEQUENCE:
result = POIDEV( xm, [ SEED = ] )
INPUTS:
xm - numeric scalar, vector or array, specifying the mean(s) of the
Poisson distribution
OUTPUT:
result - Long integer scalar or vector, same size as xm
OPTIONAL KEYWORD INPUT-OUTPUT:
SEED - Scalar to be used as the seed for the random distribution.
For best results, SEED should be a large (>100) integer.
If SEED is undefined, then its value is taken from the system
clock (see RANDOMU). The value of SEED is always updated
upon output. This keyword can be used to have POIDEV give
identical results on consecutive runs.
EXAMPLE:
(1) Add Poisson noise to an integral image array, im
IDL> imnoise = POIDEV( im)
(2) Verify the expected mean and sigma for an input value of 81
IDL> p = POIDEV( intarr(10000) + 81) ;Test for 10,000 points
IDL> print,mean(p),sigma(p)
Mean and sigma of the 10000 points should be close to 81 and 9
METHOD:
For small values (< 20) independent exponential deviates are generated
until their sum exceeds the specified mean, the number of events
required is returned as the Poisson deviate. For large (> 20) values,
uniform random variates are compared with a Lorentzian distribution
function.
NOTES:
Negative values in the input array will be returned as zeros.
REVISION HISTORY:
Version 1 Wayne Landsman July 1992
Added SEED keyword September 1992
Call intrinsic LNGAMMA function November 1994
Converted to IDL V5.0 W. Landsman September 1997
Use COMPLEMENT keyword to WHERE() W. Landsman August 2008
(See astrolib/pro/poidev.pro)
POLINT
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NAME:
POLINT
PURPOSE:
Interpolate a set of N points by fitting a polynomial of degree N-1
EXPLANATION:
Adapted from algorithm in Numerical Recipes, Press et al. (1992),
Section 3.1.
CALLING SEQUENCE
POLINT, xa, ya, x, y, [ dy ]
INPUTS:
XA - X Numeric vector, all values must be distinct. The number of
values in XA should rarely exceed 10 (i.e. a 9th order polynomial)
YA - Y Numeric vector, same number of elements
X - Numeric scalar specifying value to be interpolated
OUTPUT:
Y - Scalar, interpolated value in (XA,YA) corresponding to X
OPTIONAL OUTPUT
DY - Error estimate on Y, scalar
EXAMPLE:
Find sin(2.5) by polynomial interpolation on sin(indgen(10))
IDL> xa = indgen(10)
IDL> ya = sin( xa )
IDL> polint, xa, ya, 2.5, y ,dy
The above method gives y = .5988 & dy = 3.1e-4 a close
approximation to the actual sin(2.5) = .5985
METHOD:
Uses Neville's algorithm to iteratively build up the correct
polynomial, with each iteration containing one higher order.
REVISION HISTORY:
Written W. Landsman January, 1992
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/polint.pro)
POLYLEG
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NAME:
POLYLEG
PURPOSE:
Evaluate a Legendre polynomial with specified coefficients.
EXPLANATION:
Meant to be used analogously to the POLY function in the IDL User's
Library distribution.
CALLING SEQUENCE:
Result = POLYLEG( X, C )
INPUTS:
X - input variable, scalar or vector
C - vector of Legendre polynomial coefficients.
OUTPUTS:
POLYLEG returns a result equal to:
C[0] + C[1]*P_1(x) + C[2]*P_2(x) + ...
where P_j(x) is the jth Legendre polynomial. The output will have
the same dimensions as the input X variable.
EXAMPLE:
If x = [0.5, 1.0] and C = [2.4, 1.3, 2.5] then
print, polyleg(x, c) ====> [2.7375, 6.20]
The result can be checked using the first 3 Legendre polynomial terms
C[0] + C[1]*x + C[2]*(0.5*(3*x^2-1))
METHOD:
Uses the recurrence relation of Legendre polynomials
(n+1)*P_n+1(x) = (2n+1)*x*P_n(x) - n*P_n-1(x)
evaluated with the Clenshaw recurrence formula, see Numerical Recipes
by Press et al. (1992), Section 5.5
REVISION HISTORY:
Written W. Landsman Hughes STX Co. April, 1995
Fixed for double precision W. Landsman May, 1997
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/polyleg.pro)
POLY_SMOOTH
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NAME:
POLY_SMOOTH
PURPOSE:
Apply a least-squares (Savitzky-Golay) polynomial smoothing filter
EXPLANATION:
Reduce noise in 1-D data (e.g. time-series, spectrum) but retain
dynamic range of variations in the data by applying a least squares
smoothing polynomial filter,
Also called the Savitzky-Golay smoothing filter, cf. Numerical
Recipes (Press et al. 1992, Sec.14.8)
The low-pass filter coefficients are computed by effectively
least-squares fitting a polynomial in moving window,
centered on each data point, so the new value will be the
zero-th coefficient of the polynomial. Approximate first derivates
of the data can be computed by using first degree coefficient of
each polynomial, and so on. The filter coefficients for a specified
polynomial degree and window width are computed independent of any
data, and stored in a common block. The filter is then convolved
with the data array to result in smoothed data with reduced noise,
but retaining higher order variations (better than SMOOTH).
This procedure became partially obsolete in IDL V5.4 with the
introduction of the SAVGOL function, which computes the smoothing
coefficients.
CALLING SEQUENCE:
spectrum = poly_smooth( data, [ width, DEGREE = , NLEFT = , NRIGHT =
DERIV_ORDER = ,COEFF = ]
INPUTS:
data = 1-D array, such as a spectrum or time-series.
width = total number of data points to use in filter convolution,
(default = 5, using 2 past and 2 future data points),
must be larger than DEGREE of polynomials, and a guideline is to
make WIDTH between 1 and 2 times the FWHM of desired features.
OPTIONAL INPUT KEYWORDS:
DEGREE = degree of polynomials to use in designing the filter
via least squares fits, (default DEGREE = 2)
The higher degrees will preserve sharper features.
NLEFT = # of past data points to use in filter convolution,
excluding current point, overrides width parameter,
so that width = NLEFT + NRIGHT + 1. (default = NRIGHT)
NRIGHT = # of future data points to use (default = NLEFT).
DERIV_ORDER = order of derivative desired (default = 0, no derivative).
OPTIONAL OUTPUT KEYWORD:
COEFFICIENTS = optional output of the filter coefficients applied,
but they are all stored in common block for reuse, anyway.
RESULTS:
Function returns the data convolved with polynomial filter coefs.
EXAMPLE:
Given a wavelength - flux spectrum (w,f), apply a 31 point quadratic
smoothing filter and plot
IDL> cgplot, w, poly_smooth(f,31)
COMMON BLOCKS:
common poly_smooth, degc, nlc, nrc, coefs, ordermax
PROCEDURE:
As described in Numerical Recipies, 2nd edition sec.14.8,
Savitsky-Golay filter.
Matrix of normal eqs. is formed by starting with small terms
and then adding progressively larger terms (powers).
The filter coefficients of up to derivative ordermax are stored
in common, until the specifications change, then recompute coefficients.
Coefficients are stored in convolution order, zero lag in the middle.
MODIFICATION HISTORY:
Written, Frank Varosi NASA/GSFC 1993.
Converted to IDL V5.0 W. Landsman September 1997
Use /EDGE_TRUNCATE keyword to CONVOL W. Landsman March 2006
(See astrolib/pro/poly_smooth.pro)
POSANG
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NAME:
POSANG
PURPOSE:
Computes rigorous position angle of source 2 relative to source 1
EXPLANATION:
Computes the rigorous position angle of source 2 (with given RA, Dec)
using source 1 (with given RA, Dec) as the center.
CALLING SEQUENCE:
POSANG, U, RA1, DC1, RA2, DC2, ANGLE
INPUTS:
U -- Describes units of inputs and output:
0: everything radians
1: RAx in decimal hours, DCx in decimal
degrees, ANGLE in degrees
RA1 -- Right ascension of point 1
DC1 -- Declination of point 1
RA2 -- Right ascension of point 2
DC2 -- Declination of point 2
OUTPUTS:
ANGLE-- Angle of the great circle containing [ra2, dc2] from
the meridian containing [ra1, dc1], in the sense north
through east rotating about [ra1, dc1]. See U above
for units.
PROCEDURE:
The "four-parts formula" from spherical trig (p. 12 of Smart's
Spherical Astronomy or p. 12 of Green' Spherical Astronomy).
EXAMPLE:
For the star 56 Per, the Hipparcos catalog gives a position of
RA = 66.15593384, Dec = 33.94988843 for component A, and
RA = 66.15646079, Dec = 33.96100069 for component B. What is the
position angle of B relative to A?
IDL> RA1 = 66.15593384/15.d & DC1 = 33.95988843
IDL> RA2 = 66.15646079/15.d & DC2 = 33.96100069
IDL> posang,1,ra1,dc1,ra2,dc2, ang
will give the answer of ang = 21.4 degrees
NOTES:
(1) If RA1,DC1 are scalars, and RA2,DC2 are vectors, then ANGLE is a
vector giving the position angle between each element of RA2,DC2 and
RA1,DC1. Similarly, if RA1,DC1 are vectors, and RA2, DC2 are scalars,
then DIS is a vector giving the position angle of each element of RA1,
DC1 and RA2, DC2. If both RA1,DC1 and RA2,DC2 are vectors then ANGLE
is a vector giving the position angle between each element of RA1,DC1
and the corresponding element of RA2,DC2. If then vectors are not the
same length, then excess elements of the longer one will be ignored.
(2) Note that POSANG is not commutative -- the position angle between
A and B is theta, then the position angle between B and A is 180+theta
PROCEDURE CALLS:
ISARRAY()
HISTORY:
Modified from GCIRC, R. S. Hill, RSTX, 1 Apr. 1998
Use V6.0 notation W.L. Mar 2011
(See astrolib/pro/posang.pro)
POSITIVITY
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NAME:
POSITIVITY
PURPOSE:
Map an image uniquely and smoothly into all positive values.
EXPLANATION:
Take unconstrained x (usually an image), and map it uniquely and
smoothly into positive values. Negative values of x get mapped to
interval ( 0, sqrt( epsilon )/2 ], positive values go to
( sqrt( epsilon )/2, oo ) with deriv approaching 1. Derivative is
always 1/2 at x=0. Derivative is used by the MRL deconvolution
algorithm.
CALLING SEQUENCE:
result = POSITIVITY( x, [ /DERIVATIVE, EPSILON = )
INPUTS:
x - input array, unconstrained
OUTPUT:
result = output array = ((x + sqrt(x^2 + epsilon))/2
if the /DERIV keyword is set then instead the derivative of
the above expression with respect to X is returned
OPTIONAL INPUT KEYWORDS:
DERIV - if this keyword set, then the derivative of the positivity
mapping is returned, rather than the mapping itself
EPSILON - real scalar specifying the interval into which to map
negative values. If EPSILON EQ 0 then the mapping reduces to
positive truncation. If EPSILON LT then the mapping reduces to
an identity (no change). Default is EPSILON = 1e-9
REVISION HISTORY:
F.Varosi NASA/GSFC 1992, as suggested by R.Pina UCSD.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/positivity.pro)
PRECESS
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NAME:
PRECESS
PURPOSE:
Precess coordinates from EQUINOX1 to EQUINOX2.
EXPLANATION:
For interactive display, one can use the procedure ASTRO which calls
PRECESS or use the /PRINT keyword. The default (RA,DEC) system is
FK5 based on epoch J2000.0 but FK4 based on B1950.0 is available via
the /FK4 keyword.
Use BPRECESS and JPRECESS to convert between FK4 and FK5 systems
CALLING SEQUENCE:
PRECESS, ra, dec, [ equinox1, equinox2, /PRINT, /FK4, /RADIAN ]
INPUT - OUTPUT:
RA - Input right ascension (scalar or vector) in DEGREES, unless the
/RADIAN keyword is set
DEC - Input declination in DEGREES (scalar or vector), unless the
/RADIAN keyword is set
The input RA and DEC are modified by PRECESS to give the
values after precession.
OPTIONAL INPUTS:
EQUINOX1 - Original equinox of coordinates, numeric scalar. If
omitted, then PRECESS will query for EQUINOX1 and EQUINOX2.
EQUINOX2 - Equinox of precessed coordinates.
OPTIONAL INPUT KEYWORDS:
/PRINT - If this keyword is set and non-zero, then the precessed
coordinates are displayed at the terminal. Cannot be used
with the /RADIAN keyword
/FK4 - If this keyword is set and non-zero, the FK4 (B1950.0) system
will be used otherwise FK5 (J2000.0) will be used instead.
/RADIAN - If this keyword is set and non-zero, then the input and
output RA and DEC vectors are in radians rather than degrees
RESTRICTIONS:
Accuracy of precession decreases for declination values near 90
degrees. PRECESS should not be used more than 2.5 centuries from
2000 on the FK5 system (1950.0 on the FK4 system).
EXAMPLES:
(1) The Pole Star has J2000.0 coordinates (2h, 31m, 46.3s,
89d 15' 50.6"); compute its coordinates at J1985.0
IDL> precess, ten(2,31,46.3)*15, ten(89,15,50.6), 2000, 1985, /PRINT
====> 2h 16m 22.73s, 89d 11' 47.3"
(2) Precess the B1950 coordinates of Eps Ind (RA = 21h 59m,33.053s,
DEC = (-56d, 59', 33.053") to equinox B1975.
IDL> ra = ten(21, 59, 33.053)*15
IDL> dec = ten(-56, 59, 33.053)
IDL> precess, ra, dec ,1950, 1975, /fk4
PROCEDURE:
Algorithm from Computational Spherical Astronomy by Taff (1983),
p. 24. (FK4). FK5 constants from "Astronomical Almanac Explanatory
Supplement 1992, page 104 Table 3.211.1.
PROCEDURE CALLED:
Function PREMAT - computes precession matrix
REVISION HISTORY
Written, Wayne Landsman, STI Corporation August 1986
Correct negative output RA values February 1989
Added /PRINT keyword W. Landsman November, 1991
Provided FK5 (J2000.0) I. Freedman January 1994
Precession Matrix computation now in PREMAT W. Landsman June 1994
Added /RADIAN keyword W. Landsman June 1997
Converted to IDL V5.0 W. Landsman September 1997
Correct negative output RA values when /RADIAN used March 1999
Work for arrays, not just vectors W. Landsman September 2003
(See astrolib/pro/precess.pro)
PRECESS_CD
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NAME:
PRECESS_CD
PURPOSE:
Precess the CD (coordinate description) matrix from a FITS header
EXPLANATION:
The CD matrix is precessed from EPOCH1 to EPOCH2. Called by HPRECESS
CALLING SEQUENCE:
PRECESS_CD, cd, epoch1, epoch2, crval_old, crval_new, [/FK4]
INPUTS/OUTPUT:
CD - 2 x 2 CD (coordinate description) matrix in any units
(degrees or radians). CD will altered on output to contain
precessed values in the same units. On output CD will always
be double precision no matter how input.
INPUTS:
EPOCH1 - Original equinox of coordinates, scalar (e.g. 1950.0).
EPOCH2 - Equinox of precessed coordinates, scalar (e.g. 2000.0)
CRVAL_OLD - 2 element vector containing RA and DEC in DEGREES
of the reference pixel in the original equinox
CRVAL_NEW - 2 elements vector giving CRVAL in the new equinox
INPUT KEYWORD:
/FK4 - If this keyword is set, then the precession constants are taken
in the FK4 reference frame. The default is the FK5 frame.
RESTRICTIONS:
PRECESS_CD should not be used more than 2.5 centuries from the
year 1900.
PROCEDURE:
Adapted from the STSDAS program FMATPREC. Precession changes the
location of the north pole, and thus changes the rotation of
an image from north up. This is reflected in the precession of the
CD matrix. This is usually a very small change.
PROCEDURE CALLS:
PRECESS
REVISION HISTORY:
Written, Wayne Landsman, ST Systems February 1988
Fixed sign error in computation of SINRA March 1992
Added /FK4 keyword Feb 1994
Converted to IDL V5.0 W. Landsman September 1997
Use B/Jprecess for conversion between 1950 and 2000 W.L. Aug 2009
(See astrolib/pro/precess_cd.pro)
PRECESS_XYZ
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NAME:
PRECESS_XYZ
PURPOSE:
Precess equatorial geocentric rectangular coordinates.
CALLING SEQUENCE:
precess_xyz, x, y, z, equinox1, equinox2
INPUT/OUTPUT:
x,y,z: scalars or vectors giving heliocentric rectangular coordinates
THESE ARE CHANGED UPON RETURNING.
INPUT:
EQUINOX1: equinox of input coordinates, numeric scalar
EQUINOX2: equinox of output coordinates, numeric scalar
OUTPUT:
x,y,z are changed upon return
NOTES:
The equatorial geocentric rectangular coords are converted
to RA and Dec, precessed in the normal way, then changed
back to x, y and z using unit vectors.
EXAMPLE:
Precess 1950 equinox coords x, y and z to 2000.
IDL> precess_xyz,x,y,z, 1950, 2000
HISTORY:
Written by P. Plait/ACC March 24 1999
(unit vectors provided by D. Lindler)
Use /Radian call to PRECESS W. Landsman November 2000
Use two parameter call to ATAN W. Landsman June 2001
(See astrolib/pro/precess_xyz.pro)
PREMAT
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NAME:
PREMAT
PURPOSE:
Return the precession matrix needed to go from EQUINOX1 to EQUINOX2.
EXPLANTION:
This matrix is used by the procedures PRECESS and BARYVEL to precess
astronomical coordinates
CALLING SEQUENCE:
matrix = PREMAT( equinox1, equinox2, [ /FK4 ] )
INPUTS:
EQUINOX1 - Original equinox of coordinates, numeric scalar.
EQUINOX2 - Equinox of precessed coordinates.
OUTPUT:
matrix - double precision 3 x 3 precession matrix, used to precess
equatorial rectangular coordinates
OPTIONAL INPUT KEYWORDS:
/FK4 - If this keyword is set, the FK4 (B1950.0) system precession
angles are used to compute the precession matrix. The
default is to use FK5 (J2000.0) precession angles
EXAMPLES:
Return the precession matrix from 1950.0 to 1975.0 in the FK4 system
IDL> matrix = PREMAT( 1950.0, 1975.0, /FK4)
PROCEDURE:
FK4 constants from "Computational Spherical Astronomy" by Taff (1983),
p. 24. (FK4). FK5 constants from "Astronomical Almanac Explanatory
Supplement 1992, page 104 Table 3.211.1.
REVISION HISTORY
Written, Wayne Landsman, HSTX Corporation, June 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/premat.pro)
PRINT_STRUCT
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NAME:
PRINT_STRUCT
PURPOSE:
Print the tag values of an array of structures in nice column format.
EXPLANATION:
The tag names are displayed in a header line.
CALLING SEQUENCE:
print_struct, structure, Tags_to_print [ , title, string_matrix
FILE=, LUN_OUT=, TNUMS= , TRANGE= , FRANGE=, WHICH=
FORM_FLOAT =, MAX_ELEMENTS
INPUTS:
structure = array of structured variables
Tags_to_print = string array specifying the names of tags to print.
Default is to print all tags which are not arrays.
OPTIONAL INPUT KEYWORDS:
FILE = string, optional file name to which output will then be written.
LUN_OUT = Logical unit number for output to an open file,
default is to print to standard output.
TNUMS = tag numbers to print (alternative to specifying tag names).
TRANGE = [beg,end] tag number range to print.
FRANGE = same as TRANGE.
WHICH = optional array of subscripts to select
which structure elements to print.
FORM_FLOAT = string array of three elements specifying
floating point format, ex: FORM=['f','9','2'] means "(F9.2)",
(default float format is G12.4).
MAX_ELEMENTS = positive integer, print only tags that have less than
this number of elements (default is no screening).
/NO_TITLE - If set, then the header line of tag names is not printed
/STRINGS : instead of printing, return the array of strings in
fourth argument of procedure: string_matrix.
OUTPUTS:
title = optional string, list of tags printed/processed.
string_matrix = optional output of string matrix of tag values,
instead of printing to terminal or file, if /STRINGS.
PROCEDURE:
Check the types and lengths of fields to decide formats,
then loop and form text string from requested fields, then print.
HISTORY:
Written: Frank Varosi NASA/GSFC 1991.
F.V.1993, fixed up the print formats.
F.V.1994, added more keyword options.
F.V.1997, added WHICH and MAX_ELEM keyword options.
WBL 1997, Use UNIQ() rather than UNIQUE function
Remove call to N_STRUCT() W. Landsman March 2004
Avoid overflow with more than 10000 elements W. Landsman Nov 2005
Really remove call to N_STRUCT() W. Landsman July 2009
(See astrolib/pro/print_struct.pro)
PROB_KS
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NAME:
PROB_KS
PURPOSE:
Return the significance of the Kolmogoroff-Smirnov statistic
EXPLANATION:
Returns the significance level of an observed value of the
Kolmogorov-Smirnov statistic D for an effective number of data points
N_eff. Called by KSONE and KSTWO
CALLING SEQUENCE:
prob_ks, D, N_eff, probks
INPUT PARAMATERS:
D - Kolmogorov statistic, floating scalar, always non-negative
N_eff - Effective number of data points, scalar. For a 2 sided test
this is given by (N1*N2)/(N1+N2) where N1 and N2 are the number
of points in each data set.
OUTPUT PARAMETERS:
probks - floating scalar between 0 and 1 giving the significance level of
the K-S statistic. Small values of PROB suggest that the
distribution being tested are not the same
REVISION HISTORY:
Written W. Landsman August, 1992
Corrected typo (termbv for termbf) H. Ebeling/W.Landsman March 1996
Probably did not affect numeric result, but iteration went longer
than necessary
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/prob_ks.pro)
PROB_KUIPER
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NAME:
PROB_KUIPER
PURPOSE:
Return the significance of the Kuiper statistic
EXPLANATION:
Returns the significance level of an observed value of the
Kuiper statistic D for an effective number of data points
N_eff. Called by KUIPERONE
CALLING SEQUENCE:
prob_kuiper, D, N_eff, probks
INPUT PARAMATERS:
D - Kuiper statistic, floating scalar, always non-negative
N_eff - Effective number of data points, scalar. For a 2 sided test
this is given by (N1*N2)/(N1+N2) where N1 and N2 are the number
of points in each data set.
OUTPUT PARAMETERS:
probks - floating scalar between 0 and 1 giving the significance level of
the Kuiper statistic. Small values of PROB suggest that the
distribution being tested are not the same
REVISION HISTORY:
Written W. Landsman August, 1992
Corrected typo (termbv for termbf) H. Ebeling/W.Landsman March 1996
Probably did not affect numeric result, but iteration went longer
than necessary
Converted to IDL V5.0 W. Landsman September 1997
Adapted from PROB_KS J. Ballet July 2003
(See astrolib/pro/prob_kuiper.pro)
PSF_GAUSSIAN
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NAME:
PSF_GAUSSIAN
PURPOSE:
Create a 1-d, 2-d, or 3-d Gaussian with specified FWHM, center
EXPLANATION:
Return a point spread function having Gaussian profiles,
as either a 1D vector, a 2D image, or 3D volumetric-data.
CALLING SEQUENCE:
psf = psf_Gaussian( NPIXEL=, FWHM= , CENTROID =
[ /DOUBLE, /NORMALIZE, ST_DEV=, NDIMEN= ] )
or:
psf = psf_Gaussian( parameters, NPIXEL = ,NDIMEN = )
REQUIRED INPUT KEYWORD:
NPIXEL = number pixels for each dimension, specify as an array,
or just one number to make all sizes equal.
OPTIONAL KEYWORDS:
CENTROID = floating scalar or vector giving position of PSF center.
default is exact center of requested vector/image/volume.
The number of elements in CENTROID should equal the number of
dimensions. **The definition of Centroid was changed in
March 2002, and now an integer defines the center of a pixel.**
/DOUBLE = If set, then the output array is computed in double precision
the default is to return a floating point array.
FWHM = the desired Full-Width Half-Max (pixels) in each dimension,
specify as an array, or single number to make all the same.
NDIMEN = integer dimension of result: either 1 (vector), 2 (image), or
3 (volume), default = 2 (an image result).
/NORMALIZE causes resulting PSF to be normalized so Total( psf ) = 1.
ST_DEV = optional way to specify width by standard deviation param.
Ignored if FWHM is specified.
XY_CORREL = scalar between 0 and 1 specifying correlation coefficient
Use this keyword, for example, to specify an elliptical
Gaussian oriented at an angle to the X,Y axis. Only valid
for 2-dimensional case.
INPUTS (optional):
parameters = an NDIMEN by 3 array giving for each dimension:
[ maxval, center, st_dev ], overrides other keywords.
EXAMPLE:
(1) Create a 31 x 31 array containing a normalized centered Gaussian
with an X FWHM = 4.3 and a Y FWHM = 3.6
IDL> array = PSF_GAUSSIAN( Npixel=31, FWHM=[4.3,3.6], /NORMAL )
(2) Create a 50 pixel 1-d Gaussian vector with a maximum of 12,
centered at pixel 23 with a sigma of 19.2
IDL> psf = psf_gaussian([12,23,19.2],npixel=50)
EXTERNAL CALLS:
function Gaussian()
NOTES:
To improve speed, floating underflow exceptions are suppressed (using
the MASK=32 keyword of CHECK_MATH() rather than being flagged.
HISTORY:
Written, Frank Varosi NASA/GSFC 1991.
Suppress underflow messages, add DOUBLE keyword. **Modified centroid
definition so integer position is pixel center** W. Landsman March 2002
Allow use of the ST_DEV (not STDEV) keyword W. Landsman Nov. 2002
Do not modify NPIXEL input keyword W. Landsman
(See astrolib/pro/psf_gaussian.pro)
PUTAST
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NAME:
PUTAST
PURPOSE:
Put WCS astrometry parameters into a given FITS header.
CALLING SEQUENCE:
putast, hdr ;Prompt for all values
or
putast, hdr, astr, [EQUINOX =, CD_TYPE =, ALT= , NAXIS=]
or
putast, hdr, cd,[ crpix, crval, ctype], [ EQUINOX =, CD_TYPE =, ALT= ]
INPUTS:
HDR - FITS header, string array. HDR will be updated to contain
the supplied astrometry.
ASTR - IDL structure containing values of the astrometry parameters
CDELT, CRPIX, CRVAL, CTYPE, LONGPOLE, and PV2
See EXTAST.PRO for more info about the structure definition
or
CD - 2 x 2 array containing the astrometry parameters CD1_1 CD1_2
CD2_1 CD2_2
in units of DEGREES/PIXEL
CRPIX - 2 element vector giving X and Y coord of reference pixel
BE SURE THE COORDINATES IN CRPIX ARE GIVEN IN FITS STANDARD
(e.g. first pixel in image is [1,1] ) AND NOT IDL STANDARD
(first pixel in image is [0,0]
CRVAL - 2 element vector giving R.A. and DEC of reference pixel
in degrees
CTYPE - 2 element string vector giving projection types for the two axes.
For example, to specify a tangent projection one should set
ctype = ['RA---TAN','DEC--TAN']
OUTPUTS:
HDR - FITS header now contains the updated astrometry parameters
A brief HISTORY record is also added.
OPTIONAL KEYWORD INPUTS:
ALT - single character 'A' through 'Z' or ' ' specifying an alternate
astrometry system to write in the FITS header. The default is
to write primary astrometry or ALT = ' '. If /ALT is set,
then this is equivalent to ALT = 'A'. See Section 3.3 of
Greisen & Calabretta (2002, A&A, 395, 1061) for information about
alternate astrometry keywords.
CD_TYPE - Integer scalar, either 0, 1 or 2 specifying how the CD matrix
is to be written into the header
(0) write PCn_m values along with CDELT values
(1) convert to rotation and write as a CROTA2 value (+ CDELT)
(2) as CDn_m values (IRAF standard)
All three forms are valid representations according to Greisen &
Calabretta (2002, A&A, 395, 1061), also available at
http://fits.gsfc.nasa.gov/fits_wcs.html ) although form (0) is
preferred. Form (1) is the former AIPS standard and is now
deprecated and cannot be used if any skew is present.
If CD_TYPE is not supplied, PUTAST will try to determine the
type of astrometry already in the header. If there is no
astrometry in the header then the default is CD_TYPE = 2.
EQUINOX - numeric scalar giving the year of equinox of the reference
coordinates. Default (if EQUINOX keyword is not already
present in header) is 2000.
NAXIS - By default, PUTAST does not update the NAXIS keywords in the
FITS header. If NAXIS is set, and an astrometry structure is
supplied then the NAXIS1 and NAXIS2 keywords in the FITS header
will be updated with the .NAXIS structure tags values. If an
astrometry structure is not supplied, then one can set NAXIS to a
two element vector to update the NAXIS1, NAXIS2 keywords.
NOTES:
The recommended use of this procedure is to supply an astrometry
structure.
PUTAST does not delete astrometry parameters already present in the
header, unless they are explicity overwritten.
As of April 2012, PUTAST will add SIP
( http://fits.gsfc.nasa.gov/registry/sip.html ) distortion parameters to
a FITS header if present in the astrometry structure.
PROMPTS:
If only a header is supplied, the user will be prompted for a plate
scale, the X and Y coordinates of a reference pixel, the RA and
DEC of the reference pixel, the equinox of the RA and Dec and a
rotation angle.
PROCEDURES USED:
ADD_DISTORT, GETOPT(), GET_COORDS, GET_EQUINOX, SXADDPAR, SXPAR(),
TAG_EXIST(), ZPARCHECK
REVISION HISTORY:
Written by W. Landsman 9-3-87
Major rewrite, use new astrometry structure March, 1994
Use both CD and CDELT to get plate scale for CD_TYPE=1 September 1995
Use lower case for FITS keyword Comments W.L. March 1997
Fixed for CD_TYPE=1 and CDELT = [1.0,1.0] W.L September 1997
Default value of CD_TYPE is now 2, Use GET_COORDS to read coordinates
to correct -0 problem W.L. September 1997
Update CROTA1 if it already exists W.L. October 1997
Convert rotation to degrees for CD_TYPE = 1 W. L. June 1998
Accept CD_TYPE = 0 keyword input W.L October 1998
Remove reference to obsolete !ERR W.L. February 2000
No longer support CD001001 format, write default tangent CTYPE value
consistent conversion between CROTA and CD matrix W.L. October 2000
Use GET_EQUINOX to get equinox value W.L. January 2001
Update CTYPE keyword if previous value is 'LINEAR' W.L. July 2001
Use SIZE(/TNAME) instead of DATATYPE() W.L. November 2001
Allow direct specification of CTYPE W.L. June 2002
Don't assume celestial coordinates W. Landsman April 2003
Make default CD_TYPE = 2 W. Landsman September 2003
Add projection parameters, e.g. PV2_1, PV2_2 if present in the
input structure W. Landsman May 2004
Correct interactive computation of image center W. Landsman Feb. 2005
Don't use CROTA (CD_TYPE=1) if a skew exists W. Landsman May 2005
Added NAXIS keyword W. Landsman January 2007
Update PC matrix, if CD_TYPE=0 and CD matrix supplied W.L. July 2007
Don't write PV2 keywords for WCS types that don't use it W.L. Aug 2011
Add SIP distortion parameters if present W.L. April 2012
Work if empty distortion structure present W.L. November 2012
(See astrolib/pro/putast.pro)
QDCB_GRID
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NAME:
QDCB_GRID
PURPOSE:
Produce an overlay of latitude and longitude lines over a plot or image
EXPLANATION:
Grid is plotted on the current graphics device assuming that the
current plot is a map in the so called quad cube projection. The
output plot range is assumed to go from 7.0 to -1.0 on the X axis and
-3.0 to 3.0 on the Y axis. Within this plotting space, the quad cube
faces are laid out as follows (X=Empty, Astronomical Layout shown -
X axis can be swapped for geographic maps):
3.0_
XXX0
4321
-3.0_XXX5
| |
7.0 -1.0
CATEGORY:
Mapping Support Routine
CALLING SEQUENCE:
QDCB_GRID,[,DLONG,DLAT,[LINESTYLE=N,/LABELS]
INPUT PARAMETERS:
DLONG = Optional input longitude line spacing in degrees. If left
out, defaults to 30.
DLAT = Optional input lattitude line spacing in degrees. If left
out, defaults to 30.
OPTIONAL KEYWORD PARAMETERS:
LINESTYLE = Optional input integer specifying the linestyle to
use for drawing the grid lines.
LABELS = Optional keyword specifying that the lattitude and
longitude lines on the prime meridian and the
equator should be labeled in degrees. If LABELS is
given a value of 2, i.e. LABELS=2, then the longitude
labels will be in hours and minutes instead of
degrees.
OUTPUT PARAMETERS:
NONE
PROCEDURE:
Uses WCSSPH2XY.PRO with projection 23 ("QSC" - COBE Quadrilatieralized
Spherical Cube) to compute positions of grid lines and labels.
COPYRIGHT NOTICE:
Copyright 1991, The Regents of the University of California. This
software was produced under U.S. Government contract (W-7405-ENG-36)
by Los Alamos National Laboratory, which is operated by the
University of California for the U.S. Department of Energy.
The U.S. Government is licensed to use, reproduce, and distribute
this software. Neither the Government nor the University makes
any warranty, express or implied, or assumes any liability or
responsibility for the use of this software.
AUTHOR:
Jeff Bloch
MODIFICATIONS/REVISION LEVEL:
%I% %G%
Use WCSSPH2XY instead of QDCB Wayne Landsman December 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/qdcb_grid.pro)
QGET_STRING
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NAME:
QGET_STRING
PURPOSE:
To get a string from the keyboard without echoing it to the screen.
CALLING SEQUENCE:
string = QGET_STRING()
INPUTS:
None.
OUTPUTS:
string The string read from the keyboard.
SIDE EFFECTS:
A string variable is created and filled.
PROCEDURE:
The IDL GET_KBRD functions is used to get each character in
the string. Each character is added to the string until a
carriage return is struck. The carriage return is not appended
to the string. Striking the delete key or the backspace key
removes the previous character from the string.
NOTES:
For a widget password procedure see
http://idlcoyote.com/tip_examples/password.pro
MODIFICATION HISTORY:
Written by Michael R. Greason, STX, 8 January 1991.
Work for Mac and Windows IDL W. Landsman September 1995
(See astrolib/pro/qget_string.pro)
QSIMP
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NAME:
QSIMP
PURPOSE:
Integrate using Simpson's rule to specified accuracy.
EXPLANATION:
Integrate a function to specified accuracy using the extended
trapezoidal rule. Adapted from algorithm in Numerical Recipes,
by Press et al. (1992, 2nd edition), Section 4.2. This procedure
has been partly obsolete since IDL V3.5 with the introduction of the
intrinsic function QSIMP(), but see notes below.
CALLING SEQUENCE:
QSIMP, func, A, B, S, [ EPS = , MAX_ITER =, _EXTRA = ]
INPUTS:
func - scalar string giving name of function of one variable to
be integrated
A,B - numeric scalars giving the lower and upper bound of the
integration
OUTPUTS:
S - Scalar giving the approximation to the integral of the specified
function between A and B.
OPTIONAL KEYWORD PARAMETERS:
EPS - scalar specifying the fractional accuracy before ending the
iteration. Default = 1E-6
MAX_ITER - Integer specifying the total number iterations at which
QSIMP will terminate even if the specified accuracy has not yet
been met. The maximum number of function evaluations will be
2^(MAX_ITER). Default value is MAX_ITER = 20
Any other keywords are passed directly to the user-supplied function
via the _EXTRA facility.
NOTES:
(1) The function QTRAP is robust way of doing integrals that are not
very smooth. However, if the function has a continuous 3rd derivative
then QSIMP will likely be more efficient at performing the integral.
(2) QSIMP can be *much* faster than the intrinsic QSIMP() function (as
of IDL V7.1). This is because the intrinsic QSIMP() function only
requires that the user supplied function accept a *scalar* variable.
Thus on the the 16th iteration, the intrinsic QSIMP() makes 32,767
calls to the user function, whereas this procedure makes one call
with a 32,767 element vector. Also, unlike the intrinsic QSIMP(), this
procedure allows keywords in the user-supplied function.
(3) Since the intrinsic QSIMP() is a function, and this file contains a
procedure, there should be no name conflict.
EXAMPLE:
Compute the integral of sin(x) from 0 to !PI/3.
IDL> QSIMP, 'sin', 0, !PI/3, S & print, S
The value obtained should be cos(!PI/3) = 0.5
PROCEDURES CALLED:
TRAPZD, ZPARCHECK
REVISION HISTORY:
W. Landsman ST Systems Co. August, 1991
Continue after max iter warning message W. Landsman March, 1996
Converted to IDL V5.0 W. Landsman September 1997
Pass keyword to function via _EXTRA facility W. Landsman July 1999
(See astrolib/pro/qsimp.pro)
QTRAP
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NAME:
QTRAP
PURPOSE:
Integrate using trapezoidal rule to specified accuracy.
EXPLANATION:
Integrate a function to specified accuracy using the extended
trapezoidal rule. Adapted from Numerical Recipes (1992, 2nd edition),
Section 4.2.
CALLING SEQUENCE:
QTRAP, func, A, B, S, [EPS = , MAX_ITER =, _EXTRA = ]
INPUTS:
func - scalar string giving name of function of one variable to
be integrated
A,B - numeric scalars giving the lower and upper bound of the
integration
OUTPUTS:
S - Scalar giving the approximation to the integral of the specified
function between A and B.
OPTIONAL KEYWORD PARAMETERS:
EPS - scalar specify the fractional accuracy before ending the
iteration. Default = 1E-6
MAX_ITER - Integer specifying the total number iterations at which
QTRAP will terminate even if the specified accuracy has not yet
been met. The maximum number of function evaluations will
be 2^(MAX_ITER). Default value is MAX_ITER = 20
Any other keywords are passed directly to the user-supplied function
via the _EXTRA facility.
NOTES:
QTRAP is robust way of doing integrals that are not very smooth. If the
function has a continuous 3rd derivative then the function QSIMP will
likely be more efficient at performing the integral.
EXAMPLE:
Compute the integral of sin(x) from 0 to !PI/3.
IDL> QTRAP, 'sin', 0, !PI/3, S & print,S
The value obtained should be cos(!PI/3) = 0.5
PROCEDURES CALLED:
TRAPZD, ZPARCHECK
REVISION HISTORY:
W. Landsman ST Systems Co. August, 1991
Continue after Max Iter warning message, W. Landsman March 1996
Converted to IDL V5.0 W. Landsman September 1997
Pass keyword to function via _EXTRA facility W. Landsman July 1999
(See astrolib/pro/qtrap.pro)
QUADTERP
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NAME:
QUADTERP
PURPOSE:
Quadratic interpolation of X,Y vectors onto a new X grid
EXPLANATION:
Interpolate a function Y = f(X) at specified grid points using an
average of two neighboring 3 point quadratic (Lagrangian) interpolants.
Use LINTERP for linear interpolation
CALLING SEQUENCE:
QUADTERP, Xtab, Ytab, Xint, Yint, [ MISSING = ]
INPUT:
Xtab - Vector (X TABle) containing the current independent variable
Must be either monotonic increasing or decreasing
Ytab - Vector (Y TABle) containing the dependent variable defined
at each of the points of XTAB.
Xint - Scalar or vector giving the values of X for which interpolated
Y values are sought
OUTPUT:
Yint - Interpolated value(s) of Y, same number of points as Xint
OPTIONAL INPUT KEYWORD:
MISSING - Scalar specifying Yint value(s) to be assigned, when Xint
value(s) are outside of the range of Xtab. Default is to
truncate the out of range Yint value(s) to the nearest value
of Ytab. See the help for the INTERPOLATE function.
METHOD:
3-point Lagrangian interpolation. The average of the two quadratics
derived from the four nearest points is returned in YTAB. A single
quadratic is used near the end points. VALUE_LOCATE is used
to locate center point of the interpolation.
NOTES:
QUADTERP provides one method of high-order interpolation. The
RSI interpol.pro function includes the following alternatives:
interpol(/LSQUADRATIC) - least squares quadratic fit to a 4 pt
neighborhood
interpol(/QUADRATIC) - quadratic fit to a 3 pt neighborhood
interpol(/SPLINE) - cubic spline fit to a 4 pt neighborhood
Also, the IDL Astro function HERMITE fits a cubic polynomial and its
derivative to the two nearest points.
RESTRICTIONS:
Unless MISSING keyword is set, points outside the range of Xtab in
which valid quadratics can be computed are returned at the value
of the nearest end point of Ytab (i.e. Ytab[0] and Ytab[NPTS-1] ).
EXAMPLE:
A spectrum has been defined using a wavelength vector WAVE and a
flux vector FLUX. Interpolate onto a new wavelength grid, e.g.
IDL> wgrid = [1540.,1541.,1542.,1543.,1544.,1545.]
IDL> quadterp, wave, flux, wgrid, fgrid
FGRID will be a 5 element vector containing the quadratically
interpolated values of FLUX at the wavelengths given in WGRID.
EXTERNAL ROUTINES:
ZPARCHECK
REVISION HISTORY:
31 October 1986 by B. Boothman, adapted from the IUE RDAF
12 December 1988 J. Murthy, corrected error in Xint
September 1992, W. Landsman, fixed problem with double precision
August 1993, W. Landsman, added MISSING keyword
June, 1995, W. Landsman, use single quadratic near end points
Converted to IDL V5.0 W. Landsman September 1997
Fix occasional problem with integer X table,
YINT is a scalar if XINT is a scalar W. Landsman Dec 1999
Use VALUE_LOCATE instead of TABINV W. Landsman Feb. 2000
(See astrolib/pro/quadterp.pro)
QUERYDSS
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NAME:
QueryDSS
PURPOSE:
Query the digital sky survey (DSS) on-line at the STSCI (or ESO) server
EXPLANATION:
The script can query the DSS survey and retrieve an image and FITS
header either from the the Space Telescope Science Institute (STScI) or
European Space Observatory (ESO) servers.
See http://archive.eso.org/dss/dss and/or
http://archive.stsci.edu/dss/index.html for details.
CALLING SEQUENCE:
QueryDSS, targetname_or_coords, Im, Hdr, [IMSIZE= , /ESO, Outfile= ]
INPUTS:
TARGETNAME_OR_COORDS - Either a scalar string giving a target name,
(with J2000 coordinates determined by SIMBAD (default) or NED), or
a 2-element numeric vector giving the J2000 right ascension in
*degrees* and the target declination in degrees.
OPTIONAL INPUTS:
None
OPTIONAL KEYWORD PARAMETERS:
ImSize - Numeric scalar giving size of the image to be retrieved in
arcminutes. Default is 10 arcminute.
/ESO - Use the ESO server for image retrieval. Default is to use
the STScI server
/NED - Query the Nasa Extragalactic Database (NED) for the
target's coordinates. The default is to use Simbad for
the target search.
OUTPUT - scalar string specifying name of output FITS file.
If set, then the output IDL variables are not used.
/STSCI - obsolete keyword, now does nothing, since STSCI is the default
Server.
SURVEY - Scalar string specifying which survey to retrieve.
Possible values are
'1' - First generation (red), this is the default
'2b' - Second generation blue
'2r' - Second generation red
'2i' - Second generation near-infrared
Note that 2nd generation images may not be available for all regions
of the sky. Also note that the first two letters of the 'REGION'
keyword in the FITS header gives the bandpass 'XP' - Red IIIaF,
'XJ' - Blue IIIaJ, 'XF' - Near-IR IVN
/VERBOSE - If set, then the query sent to the DSS server is displayed
OUTPUTS:
Im - The image returned by the server. If there is an error, this
contains a single 0.
Hdr - The FITS header of the image. Empty string in case of errors.
If the OutFile keyword is set then no outputs are returned (only the
file is written).
SIDE EFFECTS:
If Im and Hdr exist in advance, they are overwritten.
RESTRICTIONS:
Relies on a working network connection.
PROCEDURE:
Construct a query-url, call WEBGET() and sort out the server's
answer.
EXAMPLE:
Retrieve an 10' image surrounding the ultracompact HII region
G45.45+0.06. Obtain the 2nd generation blue image.
IDL> QueryDSS, 'GAL045.45+00.06', image, header, survey = '2b'
IDL> tvscl, image
IDL> hprint, header
IDL> writefits,'dss_image.fits', image, header
Note that the coordinates could have been specified directly, rather than
giving the target name.
IDL> QueryDSS, [288.587, 11.1510], image, header,survey='2b'
To write a file directly to disk, use the OutFile keyword
IDL> QueryDSS, [288.587, 11.1510], survey='2b', out='gal045_2b.fits'
PROCEDURES CALLED:
QUERYSIMBAD, WEBGET()
MODIFICATION HISTORY:
Written by M. Feldt, Heidelberg, Oct 2001
Option to supply target name instead of coords W. Landsman Aug. 2002
Added OUTFILE, /NED keywords W. Landsman April 2003
Don't abort on Simbad failure W. Landsman/J. Brauher June 2003
Added /VERBOSE keyword W. Landsman Jan 2009
Make /STScI server the default W. Landsman June 2010
Fix OUTPUT option W. Landsman June 2010
(See astrolib/pro/querydss.pro)
QUERYGSC
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NAME:
QUERYGSC
PURPOSE:
Query the Guide Star Catalog (GSC V2.3.2) at STScI by position
EXPLANATION:
Uses the IDL SOCKET command to query the GSC 2.3.2 database over the Web.
Alternatively, (and more reliably) one can query the GSC 2.3.2 catalog using
queryvizier.pro and the VIZIER database, e.g.
IDL> st = queryvizier('GSC2.3',[23,35],10,/all)
GSC2.3 is an all-sky export of calibrated photographic survey plate
source parameters from the COMPASS database. The number of unique
objects is approximately 945,592,683. All sources are
from the second-generation plate-processing pipeline with the exception
of Tycho-2 and Skymap sources in the case of very bright objects. The
Skymap sources are exported when there is no matching GSC or Tycho
sources. Each GSC 2.3 entry contains only one position and one
magnitude per bandpass for each unique sky object
CALLING SEQUENCE:
info = QueryGSC(targetname_or_coords, [ dis, /HOURS] )
INPUTS:
TARGETNAME_OR_COORDS - Either a scalar string giving a target name,
(with J2000 coordinates determined by SIMBAD), or a 2-element
numeric vector giving the J2000 right ascension in *degrees* (or
hours if /HOURS is set) and the target declination in degrees.
OPTIONAL INPUT:
dis - Numeric scalar giving search radius in arcminutes to search around
specified target Default is 5 arcminutes
OPTIONAL INPUT KEYWORDS:
/BOX - if set, then radius gives a box width in arcminutes
/HOURS - If set, then the right ascension is both input and output (in
the info .ra tag) in hours instead of degrees
/VERBOSE - If set, then the CGI command to the Webserver will be displayed
;
OUTPUTS:
info - IDL structure containing information on the GSC stars within the
specified distance of the specified center. There are (currently)
23 tags in this structure -- for further information see
http://gsss.stsci.edu/Catalogs/GSC/GSC2/gsc23/gsc23_release_notes.htm
.HSTID - GSC 2.3 name for HST operations
.GSC1ID - GSC1 name
.RA,.DEC - Position in degrees (double precision). RA is given in
hours if the /HOURS keyword is set.
.RAERR, .DECERR - uncertainty (in arcseconds) in the RA and Dec
.EPOCH - mean epoch of the observation
.FPGMAG, .FPGERR - magnitude and error in photographic F
.JPGMAG, .JPGERR - magnitude and error in photographic J
.VPGMAG, .VPGERR - V magnitude and error
.NPGMAG, .NPGERR - magnitude and error
.UMAG, .UERR - magnitude and error
.BMAG, .BERR - magnitude and error
.VMAG, .VERR - magnitude and error
.RMAG, .RERR - magnitude and error
.IMAG, .IERR - magnitude and error
.JMAG, .JERR - magnitude and error
.HMAG, .HERR - magnitude and error
.KMAG, .KERR - magnitude and error
.A - semi-major axis in pixels
.PA - Position angle of extended objects in degrees
.E - eccentricity of extended objects
.CLASS - classification (0-5): 0-star, 1-galaxy, 2-blend,
3-nonstar, 4-unclassified, 5-defect
.STATUS -10 digit field used to encode more detailed information
about the properties of the catalog object. For more info, see
http://www-gsss.stsci.edu/Catalogs/GSC/GSC2/gsc23/gsc23_release_notes.htm#ClassificationCodes
.VFLAG, MFLAG - Variability nad multiplicity flags
.FPGBAND, .NPGBAND, .JPGBAND. UBAND, BBAND, .VBAND - flag as
to wether given bandpass is available
EXAMPLE:
Plot a histogram of the photographic J magnitudes of all GSC 2.3.2
stars within 10 arcminutes of the center of the globular cluster M13
IDL> info = querygsc('M13',10)
IDL> plothist,info.jpgmag,xran=[10,20]
PROCEDURES USED:
QUERYSIMBAD, RADEC, WEBGET()
MODIFICATION HISTORY:
Written by W. Landsman SSAI August 2002
Fixed parsing of RA and Dec W. Landsman September 2002
Major rewrite to use new STScI Web server, remove magrange
keyword W. Landsman Dec 2007
Update server name, added /BOX,/ VERBOSE keywords W.L 19 Dec 2007
Web server now also returns infrared data W.L. Feb 2010
Fixed case where dec neg. and deg or min 0 Pat Fry Jul 2010
(See astrolib/pro/querygsc.pro)
QUERYSIMBAD
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NAME:
QUERYSIMBAD
PURPOSE:
Query the SIMBAD/NED/Vizier astronomical name resolver to obtain coordinates
EXPLANATION:
Uses the IDL SOCKET command to query either the SIMBAD or NED nameserver
over the Web to return J2000 coordinates. ; By default, QuerySimbad
first queries the Simbad database, then (if no match found) the NED
database, and then the Vizier database.
For details on the SIMBAD service, see http://simbad.u-strasbg.fr/Simbad
and for the NED service, see http://ned.ipac.caltech.edu/
CALLING SEQUENCE:
QuerySimbad, name, ra, dec, [ id, Found=, /NED, /CADC, ERRMSG=, /VERBOSE]
INPUTS:
name - a scalar string containing the target name in SIMBAD (or NED)
nomenclature. For SIMBAD details see
http://vizier.u-strasbg.fr/cgi-bin/Dic-Simbad .
OUTPUTS:
ra - Right ascension of the target in J2000.0 in *degrees*, scalar
dec - declination of the target in degrees, scalar
OPTIONAL INPUT KEYWORD:
/CFA - if set, then use the Simbad server at the Center for Astrophysics
rather than the default server in Strasbourg, France.
ERRMSG = If defined and passed, then any error messages will be
returned to the user in this parameter rather than
depending on the MESSAGE routine in IDL. If no errors are
encountered, then a null string is returned.
/NED - if set, then only the nameserver of the NASA Extragalactic database
is used to resolve the name and return coordinates. Note that
/NED cannot be used with Galactic objects
/VERBOSE - If set, then the HTTP-GET command is displayed
/PRINT - if set, then output coordinates are displayed at the terminal
By default, the coordinates are displayed if no output parameters
are supplied to QUERYSIMBAD
/SILENT - If set, then don't print warnings if multiple SIMBAD objects
correspond to the supplied name.
OPTIONAL OUTPUT:
id - the primary SIMBAD (or NED) ID of the target, scalar string
As of June 2009, a more reliable ID seems to be found when using
CFA (/CFA) server.
OPTIONAL KEYWORD OUTPUT:
found - set to 1 if the translation was successful, or to 0 if the
the object name could not be translated by SIMBAD or NED
Errmsg - if supplied, then any error messages are returned in this
keyword, rather than being printed at the terminal. May be either
a scalar or array.
Server - Character indicating which server was actually used to resolve
the object, 'S'imbad, 'N'ed or 'V'izier
EXAMPLES:
(1) Display the J2000 coordinates for the ultracompact HII region
G45.45+0.06
IDL> QuerySimbad,'GAL045.45+00.06'
===>19 14 20.77 +11 09 3.6
PROCEDURES USED:
REPSTR(), WEBGET()
NOTES:
The actual query is made to the Sesame name resolver
( see http://cdsweb.u-strasbg.fr/doc/sesame.htx ). The Sesame
resolver first searches the Simbad name resolver, then NED and then
Vizier.
MODIFICATION HISTORY:
Written by M. Feldt, Heidelberg, Oct 2001
Minor updates, W. Landsman August 2002
Added option to use NED server, better parsing of SIMBAD names such as
IRAS F10190+5349 W. Landsman March 2003
Turn off extended name search for NED server, fix negative declination
with /NED W. Landsman April 2003
Use Simbad Sesame sever, add /Verbose, /CADC keywords
B. Stecklum, TLS Tautenburg/ W. Landsman, Feb 2007
Update NED query to account for new IPAC format, A. Barth March 2007
Update NED query to account for another new IPAC format, A. Barth
July 2007
Update message when NED does not find object W.L. October 2008
Remove CADC keyword, add CFA keyword, warning if more than two
matches W.L. November 2008
Make NED queries through the Sesame server, add Server output
keyword W.L. June 2009
Don't get primary name if user didn't ask for it W.L. Aug 2009
Added /SILENT keyword W.L. Oct 2009
Added /PRINT keyword W.L. Oct 2011
(See astrolib/pro/querysimbad.pro)
QUERYVIZIER
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NAME:
QUERYVIZIER
PURPOSE:
Query any catalog in the Vizier database by position
EXPLANATION:
Uses the IDL SOCKET command to provide a positional query of any catalog
in the the Vizier (http://vizier.u-strasbg.fr/) database over the Web and
return results in an IDL structure.
CALLING SEQUENCE:
info = QueryVizier(catalog, targetname_or_coords, [ dis
/ALLCOLUMNS, /CANADA, CONSTRAINT= ,/VERBOSE ])
INPUTS:
CATALOG - Scalar string giving the name of the VIZIER catalog to be
searched. The complete list of catalog names is available at
http://vizier.u-strasbg.fr/vizier/cats/U.htx .
Popular VIZIER catalogs include
'II/306' - Sloan SDSS photometric catalog Release 8 (2011)
'2MASS-PSC' - 2MASS point source catalog (2003)
'GSC2.3' - Version 2.3.2 of the HST Guide Star Catalog (2006)
'USNO-B1' - Verson B1 of the US Naval Observatory catalog (2003)
'UCAC4' - 4th U.S. Naval Observatory CCD Astrograph Catalog (2012)
'B/DENIS/DENIS' - 2nd Deep Near Infrared Survey of southern Sky (2005)
'I/259/TYC2' - Tycho-2 main catalog (2000)
'I/311/HIP2' - Hipparcos main catalog, new reduction (2007)
Note that some names will prompt a search of multiple catalogs
and QUERYVIZIER will only return the result of the first search.
Thus, setting catalog to "HIP2" will search all catalogs
associated with the Hipparcos mission, and return results for the
first catalog found. To specifically search the Hipparcos or
Tycho main catalogs use the VIZIER catalog names listed above
TARGETNAME_OR_COORDS - Either a scalar string giving a target name,
(with J2000 coordinates determined by SIMBAD), or a 2-element
numeric vector giving the J2000 right ascension in *degrees* and
the target declination in degrees.
If the targetname is set to 'NONE' then QUERYVIZIER will perform
an all-sky search using the constraints given in the CONSTRAINT
keyword.
OPTIONAL INPUT:
dis - scalar or 2-element vector. If one value is supplied then this
is the search radius in arcminutes. If two values are supplied
then this is the width (i.e., in longitude direction) and height
of the search box. Default is a radius search with radius of
5 arcminutes
OUTPUTS:
info - Anonymous IDL structure containing information on the catalog
sources within the specified distance of the specified center. The
structure tag names are identical with the VIZIER catalog column
names, with the exception of an occasional underscore
addition, if necessary to convert the column name to a valid
structure tag. The VIZIER Web page should consulted for the
column names and their meaning for each particular catalog..
If the tagname is numeric and the catalog field is blank then either
NaN (if floating) or -1 (if integer) is placed in the tag.
If no sources are found within the specified radius, or an
error occurs in the query then -1 is returned.
OPTIONAL KEYWORDS:
/ALLCOLUMNS - if set, then all columns for the catalog are returned
The default is to return a smaller VIZIER default set.
/CANADA - By default, the query is sent to the main VIZIER site in
Strasbourg, France. If /CANADA is set then the VIZIER site
at the Canadian Astronomical Data Center (CADC) is used instead.
Note that not all Vizier sites have the option to return
tab-separated values (TSV) which is required by this program.
CONSTRAINT - string giving additional nonpositional numeric
constraints on the entries to be selected. For example, when
in the GSC2.3 catalog, to only select sources with Rmag < 16 set
Constraint = 'Rmag<16'. Multiple constraints can be
separated by commas. Use '!=' for "not equal", '<=' for smaller
or equal, ">=" for greater than or equal. See the complete list
of operators at
http://vizier.u-strasbg.fr/doc/asu.html#AnnexQual
For this keyword only, **THE COLUMN NAME IS CASE SENSITIVE** and
must be written exactly as displayed on the VIZIER Web page.
Thus for the GSC2.3 catalog one must use 'Rmag' and not 'rmag' or
'RMAG'. In addition, *DO NOT INCLUDE ANY BLANK SPACE* unless it
is a necessary part of the query.
/SILENT - If set, then no message will be displayed if no sources
are found. Error messages are still displayed.
/VERBOSE - If set then the query sent to the VIZIER site is
displayed, along with the returned title(s) of found catalog(s)
EXAMPLES:
(1) Plot a histogram of the J magnitudes of all 2MASS point sources
stars within 10 arcminutes of the center of the globular cluster M13
IDL> info = queryvizier('2MASS-PSC','m13',10)
IDL> plothist,info.jmag,xran=[10,20]
(2) Find the brightest J mag GSC2.3 source within 3' of the
J2000 position ra = 10:12:34, dec = -23:34:35
IDL> str = queryvizier('GSC2.3',[ten(10,12,34)*15,ten(-23,34,35)],3)
IDL> print,min(str.jmag,/NAN)
(3) Find sources with V < 19 in the Magellanic Clouds Photometric
Survey (Zaritsky+, 2002) within 5 arc minutes of the position
00:47:34 -73:06:27
Checking the VIZIER Web page we find that this catalog is
IDL> catname = 'J/AJ/123/855/table1'
IDL> ra = ten(0,47,34)*15 & dec = ten(-73,6,27)
IDL> str = queryvizier(catname, [ra,dec], 5, constra='Vmag<19')
(4) Perform an all-sky search of the Tycho-2 catalog for stars with
BTmag = 13+/-0.1
IDL> str = queryvizier('I/259/TYC2','NONE',constrain='BTmag=13+/-0.1')
PROCEDURES USED:
GETTOK(), REMCHAR, REPSTR(), STRCOMPRESS2(), WEBGET()
TO DO:
(1) Allow specification of output sorting
MODIFICATION HISTORY:
Written by W. Landsman SSAI October 2003
Give structure name returned by VIZIER not that given by user
W. Landsman February 2004
Don't assume same format for all found sources W. L. March 2004
Added CONSTRAINT keyword for non-positional constraints WL July 2004
Remove use of EXECUTE() statement WL June 2005
Make dis optional as advertised WL August 2005
Update for change in Vizier output format WL February 2006
Fix problem in Feb 2006 update when only 1 object found
WL/D.Apai March 2006
Accept 'E' format for floating point. M. Perrin April 2006
Added /ALLCOLUMNS option to return even more data. M. Perrin, May 2006
Return anonymous structure W. Landsman May 2006
Removed V6.0 notation to restore V5 compatibility W.Landsman July2006
Accept target='NONE' for all-sky search, allow '+/-' constraints
W. Landsman October 2006
Use HTTP 1.0 protocol in call to webget.pro
Use vector form of IDL_VALIDNAME if V6.4 or later W.L. Dec 2007
Update Strasbourg Web address for target name W.L. 3 March 2008
Also update Web address for coordinate search W.L. 7 March 2008
Allow for 'D' specification format R. Gutermuth/W.L. June 2008
Allow for possible lower-case returned formats W.L. July 2008
Use STRCOMPRESS2()to remove blanks around operators in constraint
string W.L. August 2008
Added /SILENT keyword W.L. Jan 2009
Avoid error if output columns but not data returned W.L. Mar 2010
Ignore vector tags (e.g. SED spectra) W.L. April 2011
Better checking when more than one catalog returned W.L. June 2012
(See astrolib/pro/queryvizier.pro)
RADEC
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NAME:
RADEC
PURPOSE:
To convert RA and Dec from decimal to sexagesimal units.
EXPLANATION:
The conversion is to sexagesimal hours for RA, and sexagesimal
degrees for declination.
CALLING SEQUENCE:
radec, ra, dec, ihr, imin, xsec, ideg, imn, xsc, [/HOURS}
INPUTS:
ra - Right ascension, scalar or vector, in DEGREES unless the
/HOURS keyword is set
dec - declination in decimal DEGREES, scalar or vector, same number
of elements as RA
OUTPUTS:
ihr - right ascension hours (INTEGER*2)
imin - right ascension minutes (INTEGER*2)
xsec - right ascension seconds (REAL*4 or REAL*8)
ideg - declination degrees (INTEGER*2)
imn - declination minutes (INTEGER*2)
xsc - declination seconds (REAL*4 or REAL*8)
OPTIONAL KEYWORD INPUT:
/HOURS - if set, then the input righ ascension should be specified in
hours instead of degrees.
RESTRICTIONS:
RADEC does minimal parameter checking.
REVISON HISTORY:
Written by B. Pfarr, STX, 4/24/87
Converted to IDL V5.0 W. Landsman September 1997
Added /HOURS keyword W. Landsman August 2002
(See astrolib/pro/radec.pro)
RANDOMCHI
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NAME:
RANDOMCHI
PURPOSE:
GENERATE CHI-SQUARE DISTRIBUTED RANDOM VARIABLES.
AUTHOR : BRANDON C. KELLY, STEWARD OBS., SEP 2005
INPUTS :
SEED - THE SEED FOR THE RANDOM NUMBER GENERATOR, CAN BE UNDEFINED.
DOF - THE DEGREES OF FREEDOM FOR THE CHI-SQUARED DISTRIBUTION.
OPTIONAL INPUTS :
NRAND - THE NUMBER OF RANDOM NUMBERS TO DRAW
(See astrolib/pro/randomchi.pro)
RANDOMDIR
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NAME:
RANDOMDIR
PURPOSE:
GENERATE DIRICHLET-DISTRIBUTED RANDOM VARIABLES.
AUTHOR : BRANDON C. KELLY, STEWARD OBS., APRIL 2006
INPUTS :
SEED - THE SEED FOR THE RANDOM NUMBER GENERATOR, CAN BE UNDEFINED.
ALPHA - THE SHAPE PARAMETERS FOR THE DIRICHLET DISTRIBUTION. THIS
SHOULD BE A K-ELEMENT VECTOR.
OPTIONAL INPUTS :
NRAND - THE NUMBER OF RANDOM NUMBERS TO DRAW
CALLED ROUTINES :
RANDOMGAM
(See astrolib/pro/randomdir.pro)
RANDOMGAM
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NAME:
RANDOMGAM
PURPOSE:
GENERATE GAMMA-DISTRIBUTED RANDOM VARIABLES.
AUTHOR : BRANDON C. KELLY, STEWARD OBS., APRIL 2006
INPUTS :
SEED - THE SEED FOR THE RANDOM NUMBER GENERATOR, CAN BE UNDEFINED.
ALPHA, BETA - THE SHAPE PARAMETERS FOR THE GAMMA DISTRIBUTION.
OPTIONAL INPUTS :
NRAND - THE NUMBER OF RANDOM NUMBERS TO DRAW
(See astrolib/pro/randomgam.pro)
RANDOMP
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NAME:
RANDOMP
PURPOSE:
Generates an array of random numbers distributed as a power law.
CALLING SEQUENCE:
RANDOMP, X, Pow, N, [ RANGE_X = [low,high], SEED= ]'
INPUTS:
Pow: Exponent of power law.
The pdf of X is f_X(x) = A*x^pow, low <= x <= high
ASTRONOMERS PLEASE NOTE:
pow is little gamma = big gamma - 1 for stellar IMFs.
N: Number of elements in generated vector.
OPTIONAL INPUT KEYWORD PARAMETER:
RANGE_X: 2-element vector [low,high] specifying the range of
output X values; the default is [5, 100].
OPTIONAL INPUT-OUTPUT KEYWORD PARAMETER:
SEED: Seed value for RANDOMU function. As described in the
documentation for RANDOMU, the value of SEED is updated on
each call to RANDOMP, and taken from the system clock if not
supplied. This keyword can be used to have RANDOMP give
identical results on different runs.
OUTPUTS:
X: Vector of random numbers, distributed as a power law between
specified range
PROCEDURE:
"Transformation Method" for random variables is described in Bevington
& Robinson, "Data Reduction & Error Analysis for Physical Sciences", 2nd
Edition (McGraw-Hill, 1992). p. 83.
Output of RANDOMU function is transformed to power-law
random variable.
EXAMPLE:
Create a stellar initial mass function (IMF) with 10000 stars
ranging from 0.5 to 100 solar masses and a Salpeter slope. Enter:
RANDOMP,MASS,-2.35,10000,RANGE_X=[0.5,100]
NOTES:
Versions 5.1.1 and V5.2 of IDL have a bug in RANDOMU such that the SEED
value is initialized to the same value at the start of each session,
rather than being initialized by the system clock. RANDOMP will be
affected in a similar manner.
MODIFICATION HISTORY:
Written by R. S. Hill, Hughes STX, July 13, 1995
July 14, 1995 SEED keyword added at Landsman's suggestion.
Documentation converted to standard format. RSH
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/randomp.pro)
RANDOMWISH
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NAME:
RANDOMWISH
PURUPOSE:
ROUTINE TO DRAW RANDOM MATRICES FROM A WISHART DISTRIBUTION WITH DOF
DEGREES OF FREEDOM AND SCALE MATRIX S.
AUTHOR : BRANDON C. KELLY, STEWARD OBS., JULY 2006
INPUTS :
SEED - THE SEED FOR THE RANDOM NUMBER GENERATOR, CAN BE UNDEFINED.
DOF - THE DEGREES OF FREEDOM FOR THE WISHART DISTRIBUTION.
S - THE SCALE MATRIX. THE DIMENSION OF S CANNOT BE GREATER THAN
DOF.
OPTIONAL INPUTS :
NRAND - THE NUMBER OF RANDOM MATRICES TO DRAW
CALLED ROUTINES :
MRANDOMN
(See astrolib/pro/randomwish.pro)
RDFITS_STRUCT
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NAME:
RDFITS_STRUCT
PURPOSE:
Read an entire FITS file (all extensions) into a single IDL structure.
EXPLANATION:
Each header, image or table array is placed in a separate structure
tag.
CALLING SEQUENCE:
RDFITS_STRUCT, filename, struct, /SILENT, /HEADER_ONLY, EXTEN= ]
INPUT:
FILENAME = Scalar string giving the name of the FITS file.
One can also specify a gzip (.gz) compressed file
OPTIONAL KEYWORD:
/HEADER_ONLY - If set, then only the FITS headers (and not the data)
are read into the structure.
/SILENT - Set this keyword to suppress informational displays at the
terminal.
OUTPUT:
struct = structure into which FITS data is read. The primary header
and image are placed into tag names HDR0 and IM0. The ith
extension is placed into the tag names HDRi, and either TABi
(if it is a binary or ASCII table) or IMi (if it is an image
extension)
If /HEADER_ONLY is set, then struct will contain tags HDR0, HDR1
....HDRn containing all the headers of a FITS file with n
extensions
OPTIONAL INPUT KEYWORD:
EXTEN - positive integer array specifying which extensions to read.
Default is to read all extensions.
PROCEDURES USED:
FITS_OPEN, FITS_READ, FITS_CLOSE
METHOD:
The file is opened with FITS_OPEN which return information on the
number and type of each extension. The CREATE_STRUCT() function
is used iteratively, with FITS_READ calls to build the final structure.
EXAMPLE:
Read the FITS file 'm33.fits' into an IDL structure, st
IDL> rdfits_struct, 'm33.fits', st
IDL> help, /str, st ;Display info about the structure
To just read the second and fourth extensions
IDL> rdfits_struct, 'm33.fits', st, exten=[2,4]
RESTRICTIONS:
Does not handle random groups or variable length binary tables
MODIFICATION HISTORY:
Written K. Venkatakrishna, STX April 1992
Code cleaned up a bit W. Landsman STX October 92
Modified for MacOS I. Freedman HSTX April 1994
Work under Windows 95 W. Landsman HSTX January 1996
Use anonymous structures, skip extensions without data WBL April 1998
Converted to IDL V5.0, W. Landsman, April 1998
OS-independent deletion of temporary file W. Landsman Jan 1999
Major rewrite to use FITS_OPEN and CREATE_STRUCT() W. Landsman Sep 2002
Added /HEADER_ONLY keyword W. Landsman October 2003
Do not copy primary header into extension headers W. Landsman Dec 2004
Do not modify NAXIS when using /HEADER_ONLY W. Landsman Jan 2005
Added EXTEN keyword W. Landsman July 2009
(See astrolib/pro/rdfits_struct.pro)
RDFLOAT
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NAME:
RDFLOAT
PURPOSE:
Quickly read a numeric ASCII data file into IDL floating/double vectors.
EXPLANATION:
Columns of data may be separated by tabs or spaces. This
program is fast but is restricted to data files where all columns can
be read as floating point (or all double precision).
Use READCOL if greater flexibility is desired. Use READFMT to read a
fixed-format ASCII file. Use FORPRINT to print columns of data.
CALLING SEQUENCE:
RDFLOAT, name, v1, [ v2, v3, v4, v5, ... v19]
COLUMNS, /DOUBLE, SKIPLINE = , NUMLINE = ]
INPUTS:
NAME - Name of ASCII data file, scalar string. In VMS, an extension of
.DAT is assumed, if not supplied.
OPTIONAL INPUT KEYWORDS:
COLUMNS - Numeric scalar or vector specifying which columns in the file
to read. For example, if COLUMNS = [3,7,11] then the first
output variable (v1) would contain column 3, the second would
contain column 7 and the third would contain column 11. If
the number of elements in the COLUMNS vector is less than the
number of output parameters, then consecutive columns are
implied. For example, if 3 output parameters are supplied
(v1,v2,v3) and COLUMNS = 3, then columns 3,4, and 5 will be
read.
SKIPLINE - Integer scalar specifying number of lines to skip at the top
of file before reading. Default is to start at the first line.
NUMLINE - Integer scalar specifying number of lines in the file to read.
Default is to read the entire file
/DOUBLE - If this keyword is set, then all variables are read in as
double precision.
/SILENT - Set this keyword to suppress any informative messages
OUTPUTS:
V1,V2,V3,...V19 - IDL vectors to contain columns of data.
Up to 19 columns may be read. All output vectors are of type
float, unless the /DOUBLE keyword is set,
EXAMPLES:
Each row in a file 'position.dat' contains a star number and 6 columns
of data giving an RA and Dec in sexagesimal format. Read into IDL
variables.
IDL> rdfloat,'position.dat',ID,hr,min,sec,deg,dmin,dsec
All output vectors will be floating point. To only read the
declination vectors (Deg,dmin,dsec)
IDL> rdfloat,'position.dat',deg,dmin,dsec,col=4
RESTRICTIONS:
(1) All rows in the file must be formatted identically (except for
those skipped by SKIPLINE). RDFLOAT reads the first line of
the data (after SKIPLINE) to determine the number of columns of
data.
(2) Cannot be used to read strings
PROCEDURES USED:
None.
REVISION HISTORY:
Written W. Landsman September 1995
Call NUMLINES() function February 1996
Read up to 19 columns August 1997
Converted to IDL V5.0 W. Landsman September 1997
Allow to skip more than 32767 lines W. Landsman June 2001
Added /SILENT keyword W. Landsman March 2002
Added COLUMNS keyword, use STRSPLIT W. Landsman May 2002
Use SKIP_LUN if V5.6 or later W. Landsman Nov 2002
V5.6 version, use FILE_LINES() W. Landsman Dec 2002
(See astrolib/pro/rdfloat.pro)
RDPLOT
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NAME:
RDPLOT
PURPOSE:
Like CURSOR but with a full-screen cursor and continuous readout option
EXPLANATION:
This program is designed to essentially mimic the IDL CURSOR command,
but with the additional options of continuously printing out the data
values of the cursor's position, and using a full-screen cursor rather
than a small cross cursor. The full screen cursor uses OPLOT and
X-windows graphics masking to emulate the cursor.
One difference is that IF the PRINT keyword is set but the DOWN,
WAIT, CHANGE, or NOWAIT keywords are not set, then the leftmost mouse
button will print a "newline" line-feed, but not exit.
CALLING SEQUENCE:
RDPLOT [, X, Y] [, WaitFlag] [, /DATA | /DEVICE | /NORMAL]
[, /NOWAIT | /WAIT | /DOWN | /CHANGE]
[, /FULLCURSOR] [, /NOCLIP] [, /CROSS] [, /ACCUMULATE]
[, ERR=, PRINT=, XTITLE=, YTITLE=, XVALUES=, YVALUES=
, LINESTYLE=, THICK=, COLOR=, BACKGROUND=]
REQUIRED INPUTS:
None.
OPTIONAL INPUTS:
WAITFLAG = Uses the same table as the intrinsic CURSOR command, But note
that unlike the CURSOR command, there is no UP keyword.
WaitFlag=0 sets the NOWAIT keyword
WaitFlag=1 sets the WAIT keyword {default}
WaitFlag=2 sets the CHANGE keyword
WaitFlag=3 sets the DOWN keyword
OPTIONAL OUTPUTS:
X - a named variable to receive the final cursor X position, scalar
or vector (if /ACCUMULATE is set)
Y - a named variable to receive the final cursor Y position, scalar
or vector (if /ACCUMULATE is set)
OPTIONAL KEYWORD INPUT PARAMETERS:
/DATA - data coordinates are displayed and returned.
/DEVICE - device coordinates are displayed and returned.
/NORMAL - normal coordinates are displayed and returned.
Default is to use DATA coordinates if available (see notes).
/NOWAIT = if non-zero the routine will immediately return the cursor's
present position.
/WAIT - if non-zero will wait for a mouse key click before returning. If
cursor key is already down, then procedure immediately exits.
/DOWN - equivalent to WAIT *except* that if the mouse key is already down
when the procedure is called, the procedure will wait until the mouse
key is clicked down again.
/CHANGE - returns when the mouse is moved OR a key is clicked up or down.
PRINT = if non-zero will continuously print out (at the terminal) the data
values of the cursor's position. If PRINT>1, program will printout a
brief header describing the mouse button functions. However, note that
the button functions are overridden if any of the DOWN, WAIT, or
CHANGE values are non-zero.
XTITLE = label used to describe the values of the abscissa if PRINT>0.
YTITLE = label used to describe the values of the ordinate if PRINT>0.
XVALUES = a vector corresponding to the values to be printed when the
PRINT keyword is set. This allows the user the option of printing
out other values rather than the default X coordinate position of
the cursor. E.g., if XVALUES is a string vector of dates such as
['May 1', 'May 2', ...], then those dates will be printed rather than
the X value of the cursor's position: if X=1 then 'May 2' would be
printed, etc. This requires that the values of the X coordinate read
by the cursor must be positive (can't access negative elements).
If XVALUES=-1, then NO values for X will be printed.
YVALUES = analogous to the XVALUES keyword.
/FULLCURSOR - if non-zero default cursor is blanked out and full-screen
(or full plot window, depending on the value of NOCLIP) lines are
drawn; their intersecton is centered on the cursor position.
/NOCLIP - if non-zero will make a full-screen cursor, otherwise it will
default to the value in !P.NOCLIP.
LINESTYLE = style of line that makes the full-screen cursor.
THICK = thickness of the line that makes the full-screen cursor.
COLOR = color of the full-screen cursor.
BACKGROUND = color of the background of the plot device. If this has
been set to !P.BackGround, then this keyword is unnecessary.
CROSS = if non-zero will show the regular cross AND full screen cursors.
/ACCUMULATE - all of the positions for which the left button was
clicked are stored in the X and Y variables. Has no effect if X and Y
are not present.
OPTIONAL KEYWORD OUTPUT PARAMETER:
ERR = returns the most recent value of the !mouse.button value.
NOTES:
Note that this procedure does not allow the "UP" keyword/flag...which
doesn't seem to work too well in the origianl CURSOR version anyway.
If a data coordinate system has not been established, then RDPLOT will
create one identical to the device coordinate system. Note that this
kluge is required even if the user specified /NORMAL coordinates, since
RDPLOT makes use of the OPLOT procedure. This new data coordinate system
is effectively "erased" (!X.CRange and !Y.CRange are both set to zero)
upon exit of the routine so as to not change the plot status from the
user's point of view.
Only tested on X-windows systems. If this program is interrupted, the
graphics function might be left in a non-standard state; in that case,
run the program RESET_RDPLOT to return the standard graphics functions,
or type the command: DEVICE, /CURSOR_CROSS, SET_GRAPHICS=3, BYPASS=0
Robishaw added /ACCUMULATE keyword to pass back all the positions at
which the mouse was left-clicked. In addition, the value of the exit
click is returned unless the cursor did not change position between the
last left-click and the exit click.
BUGS:
NOTE: (1/27/05) The bugs below have been fixed by Robishaw and tested
on Solaris, Linux and OS-X.
It is assumed that the current background of the plot is correctly
defined by the value in !P.Background. Otherwise, the color of the
long cursor probably will not be correct. Sometimes the color doesn't
work anyway, and I'm not sure why.
NOTE: Robishaw fixed this 1/27/05.
There may be some cases (e.g., when THICK>1 and NOCLIP=0) when the
full-screen cursor is not correctly erased, leaving "ghost images" on the
plot. It just seems that the screen updates get slow or the positions
ambiguous with a thick line and the cursor off the plot.
NOTE: Robishaw fixed this 1/27/05.
PROCEDURE:
Basically is a bells-n-whistles version of the CURSOR procedure. All
the details are covered in the above discussion of the keywords.
EXAMPLES:
A silly, but informative one:
Months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', $
'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
plot, indgen(12), xrange=[-5, 15]
rdplot, /FULL, /PRINT, XTITLE='Month: ', YTITLE='Y-value per month = ', $
xvalues=Months
If your plot has a non-black background color, be sure to set either
!p.background or the BACKGROUND keyword. Here are examples of how to
use a blue full-screen cursor on a plot with a red background and
yellow axes and data. First, deal with color decomposition off:
device, decomposed=0
tvlct, [255,255,0], [0,255,0], [0,0,255], 1
plot, randomn(seed,1024), XSTYLE=19, PSYM=3, COLOR=2, BACK=1
rdplot, /PRINT, /FULL, THICK=5, /NOCLIP, BACK=1, COLOR=3
For decomposition on (TrueColor or DirectColor only):
device, decomposed=1
plot, randomn(seed,1024), XSTYLE=19, PSYM=3, COLOR=65535l, BACK=255l
rdplot, /PRINT, /FULL, THICK=5, /NOCLIP, BACK=255l, COLOR=16711680l
MODIFICATION HISTORY:
Written (originally named CURFULL) by J.Wm.Parker 1993 Nov 22
Created data coordinates if not already present, W. Landsman Nov. 93
Added continuous printout of data values, COLOR and FULLCURSOR keywords
(so that default is that it acts just like the cursor command).
Changed name from CURFULL to RDPLOT. J.Wm.Parker 1994 Apr 20
Modified (with some translation table assistance from the IDL support
group) to correctly plot the crosshair with the desired IDL
color using the device's translation table to determine the XOR
function and using the BYPASS function. Added the RESET_RDPLOT
procedure to cleanup crashes that might occur while running
RDPLOT. Other minor changes/bug fixes. J.Wm.Parker 1994 May 21
Modified DOWN, WAIT, CHANGE functions to behave more similar to the
generic CURSOR procedure. J.Wm.Parker 1995 April 24
Added XVALUES, YVALUES keywords and cleanup. J.Wm.Parker 1995 April 24
Convert to IDL V5.0, W. Landsman July 1998
Change !D.NCOLORS to !D.TABLE_SIZE for 24 bit displays W. Landsman May 2000
Skip translation table for TrueColor visuals W. Landsman March 2001
Fixed /FULLCURSOR ghosts. Fixed to properly deal with background colors
in 24-bit visual classes (TrueColor and DirectColor). Added
BACKGROUND keyword. Tim Robishaw 2005 Jan 27
Added /ACCUMULATE keyword. T. Robishaw 2006 Nov 8
Corrected following problems. When /CHANGE and /PRINT were set,
returned X & Y were different than those printed. When /PRINT and
/NOWAIT were set, or /PRINT and /WAIT were set and the routine was
entered with a mouse button clicked, nothing was printed. When
/PRINT and /DOWN were set, if routine was started with button down,
advertised behavior was that routine would exit on next down click;
in practice if cursor was not moved, successive down clicks had no
effect. Now, if X is passed as an output variable, requires that Y
is also passed, like CURSOR. Bottom line is that RDPLOT now really
does behave like CURSOR and when /PRINT is set, the values printed
correspond to those returned in X & Y. T. Robishaw 2006 Nov 12
Fixed misbehavior when color decomposition was set to off for
TrueColor and DirectColor. Now thoroughly tested on PseudoColor
displays as well as both decomposition states for TrueColor and
DirectColor. Also made the default cursor color white when
decomposition is on (this has been its default value for
decomposition off). T. Robishaw 2006 Nov 16
(See astrolib/pro/rdplot.pro)
RDPSF
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NAME:
RDPSF
PURPOSE:
Read the FITS file created by GETPSF in the DAOPHOT sequence
EXPLANATION:
Combines the Gaussian with the residuals to create an output PSF array.
CALLING SEQUENCE:
RDPSF, PSF, HPSF, [ PSFname]
OPTIONAL INPUTS
PSFname - string giving the name of the FITS file containing the PSF
residuals
OUTPUTS
psf - array containing the actual PSF
hpsf - header associated with psf
PROCEDURES CALLED:
DAO_VALUE(), MAKE_2D, SXADDPAR, READFITS(), SXPAR()
REVISION HISTORY:
Written W. Landsman December, 1988
Checked for IDL Version 2, J. Isensee & J. Hill, December, 1990
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/rdpsf.pro)
READCOL
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NAME:
READCOL
PURPOSE:
Read a free-format ASCII file with columns of data into IDL vectors
EXPLANATION:
Lines of data not meeting the specified format (e.g. comments) are
ignored. By default, columns may be separated by commas or spaces.
Use READFMT to read a fixed-format ASCII file. Use RDFLOAT for
much faster I/O (but less flexibility). Use FORPRINT to write
columns of data (inverse of READCOL).
If you sure that all lines meet the specified format (excluding
commented and SKIPed lines) then the speed for reading large files
can be significantly improved by setting the /QUICK keyword.
CALLING SEQUENCE:
READCOL, name, v1, [ v2, v3, v4, v5, ... v40 , COMMENT=, /NAN
DELIMITER= ,FORMAT = , /DEBUG , /SILENT , SKIPLINE = , NUMLINE =
COUNT =, STRINGSKIP=
INPUTS:
NAME - Name of ASCII data file, scalar string.
OPTIONAL INPUT KEYWORDS:
FORMAT - scalar string containing a letter specifying an IDL type
for each column of data to be read. Allowed letters are
A - string data, B - byte, D - double precision, F- floating
point, I - short integer, L - longword, LL - 64 bit integer,
U - unsigned short integer, UL - unsigned long integer
Z - longword hexadecimal, and X - skip a column.
Columns without a specified format are assumed to be floating
point. Examples of valid values of FMT are
'A,B,I' ;First column to read as a character string, then
1 column of byte data, 1 column integer data
'L,L,L,L' ;Four columns will be read as longword arrays.
' ' ;All columns are floating point
If a FORMAT keyword string is not supplied, then all columns are
assumed to be floating point.
/SILENT - Normally, READCOL will display each line that it skips over.
If SILENT is set and non-zero then these messages will be
suppressed.
/DEBUG - If this keyword is non-zero, then additional information is
printed as READCOL attempts to read and interpret the file.
COMMENT - single character specifying comment character. Any line
beginning with this character will be skipped. Default is
no comment lines.
/COMPRESS - If set, then the file is assumed to be gzip compressed.
There is no automatic recognition of compressed files
by extension type.
DELIMITER - Character(s) specifying delimiter used to separate
columns. Usually a single character but, e.g. delimiter=':,'
specifies that either a colon or comma as a delimiter.
Set DELIM = string(9b) to read tab separated data
The default delimiter is either a comma or a blank.
/NAN - if set, then an empty field will be read into a floating or
double numeric variable as NaN; by default an empty field is
converted to 0.0.
/PRESERVE_NULL - If set, then spaces are considered to be valid fields,
useful if the columns contain missing data. Note that between
April and December 2006, /PRESERVE_NULL was the default.
/QUICK - If set, then READCOL does not check that each individual line
matches the supplied format. This makes READCOL less
flexible but can provide a significant speed improvement when
reading large files.
SKIPLINE - Scalar specifying number of lines to skip at the top of file
before reading. Default is to start at the first line.
NUMLINE - Scalar specifying number of lines in the file to read.
Default is to read the entire file
STRINGSKIP - will skip all lines that begin with the specified string.
(Unlike COMMENT this can be more than 1 character.) Useful to
skip over comment lines.
OUTPUTS:
V1,V2,V3,...V40 - IDL vectors to contain columns of data.
Up to 40 columns may be read. The type of the output vectors
are as specified by FORMAT.
OPTIONAL OUTPUT KEYWORDS:
COUNT - integer giving the number of valid lines actually read
NLINES - integer giving the total number of lines in the file
(as returned by FILE_LINES)
EXAMPLES:
Each row in a file position.dat contains a star name and 6 columns
of data giving an RA and Dec in sexagesimal format. Read into IDL
variables. (NOTE: The star names must not include the delimiter
as a part of the name, no spaces or commas as default.)
IDL> FMT = 'A,I,I,F,I,I,F'
IDL> READCOL,'position.dat',F=FMT,name,hr,min,sec,deg,dmin,dsec
The HR,MIN,DEG, and DMIN variables will be integer vectors.
Alternatively, all except the first column could be specified as
floating point.
IDL> READCOL,'position.dat',F='A',name,hr,min,sec,deg,dmin,dsec
To read just the variables HR,MIN,SEC
IDL> READCOL,'position.dat',F='X,I,I,F',HR,MIN,SEC
RESTRICTIONS:
This procedure is designed for generality and not for speed.
If a large ASCII file is to be read repeatedly, it may be worth
writing a specialized reader.
Columns to be read as strings must not contain the delimiter character
(i.e. commas or spaces by default). Either change the default
delimiter with the DELIMITER keyword, or use READFMT to read such files.
Numeric values are converted to specified format. For example,
the value 0.13 read with an 'I' format will be converted to 0.
PROCEDURES CALLED
GETTOK(), STRNUMBER()
The version of STRNUMBER() must be after August 2006.
REVISION HISTORY:
Written W. Landsman November, 1988
Modified J. Bloch June, 1991
(Fixed problem with over allocation of logical units.)
Added SKIPLINE and NUMLINE keywords W. Landsman March 92
Read a maximum of 25 cols. Joan Isensee, Hughes STX Corp., 15-SEP-93.
Call NUMLINES() function W. Landsman Feb. 1996
Added DELIMITER keyword W. Landsman Nov. 1999
Fix indexing typos (i for k) that mysteriously appeared W. L. Mar. 2000
Hexadecimal support added. MRG, RITSS, 15 March 2000.
Default is comma or space delimiters as advertised W.L. July 2001
Faster algorithm, use STRSPLIT if V5.3 or later W.L. May 2002
Accept null strings separated by delimiter ,e.g. ',,,'
Use SCOPE_VARFETCH instead of EXECUTE() for >V6.1 W.L. Jun 2005
Added compile_opt idl2 W. L. July 2005
Added the NaN keyword W. L August 2006
Added /PRESERVE_NULL keyword W.L. January 2007
Assume since V5.6 (FILE_LINES available ) W.L. Nov 2007
Added COUNT output keyword W.L. Aug 2008
Added NLINES output keyword W.L. Nov 2008
Added SKIPSTART keyword Stephane Beland January 2008
Renamed SKIPSTART to STRINGSKIP to keep meaning of SKIP W.L. Feb 2008
Assume since V6.1, SCOPE_VARFETCH available W.L. July 2009
Read up to 40 columns W.L. Aug 2009
Use pointers instead of SCOPE_VARFETCH. Fixes bug with
IDL Workbench and runs 20% faster Douglas J. Marshall/W.L. Nov 2009
Recognize LL, UL, and ULL data types, don't use 'val' output from
STRNUMBER() W.L. Feb 2010
Graceful return even if no valid lines are present D. Sahnow April 2010
Ability to read tab separated data WL April 2010
Free memory used by pointers WL July 2010
Added /QUICK keyword WL Sep 2010
Accept normal FORTRAN formats (e.g. F5.1) P. Noterdaeme/W.L Jan 2011
Add COMPRESS keyword, IDL 6 notation W. Landsman/J. Bailin Feb 2011
Allow filename to be 1 element array W.Landsman/S.Antonille Apr 2011
Feb 2010 change caused errors when reading blanks as numbers.
W.L. July 2012
(See astrolib/pro/readcol.pro)
READFITS
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NAME:
READFITS
PURPOSE:
Read a FITS file into IDL data and header variables.
EXPLANATION:
READFITS() can read FITS files compressed with gzip or Unix (.Z)
compression. FPACK ( http://heasarc.gsfc.nasa.gov/fitsio/fpack/ )
compressed FITS files can also be read provided that the FPACK software
is installed.
See http://idlastro.gsfc.nasa.gov/fitsio.html for other ways of
reading FITS files with IDL.
CALLING SEQUENCE:
Result = READFITS( Filename/Fileunit,[ Header, heap, /NOSCALE, EXTEN_NO=,
NSLICE=, /SILENT , STARTROW =, NUMROW = , HBUFFER=,
/CHECKSUM, /COMPRESS, /FPACK, /No_Unsigned, NaNVALUE = ]
INPUTS:
Filename = Scalar string containing the name of the FITS file
(including extension) to be read. If the filename has
a *.gz extension, it will be treated as a gzip compressed
file. If it has a .Z extension, it will be treated as a
Unix compressed file. If Filename is an empty string then
the user will be queried for the file name.
OR
Fileunit - A scalar integer specifying the unit of an already opened
FITS file. The unit will remain open after exiting
READFITS(). There are two possible reasons for choosing
to specify a unit number rather than a file name:
(1) For a FITS file with many extensions, one can move to the
desired extensions with FXPOSIT() and then use READFITS(). This
is more efficient than repeatedly starting at the beginning of
the file.
(2) For reading a FITS file across a Web http: address after opening
the unit with the SOCKET procedure
OUTPUTS:
Result = FITS data array constructed from designated record.
If the specified file was not found, then Result = -1
OPTIONAL OUTPUT:
Header = String array containing the header from the FITS file.
If you don't need the header, then the speed may be improved by
not supplying this parameter. Note however, that omitting
the header can imply /NOSCALE, i.e. BSCALE and BZERO values
may not be applied.
heap = For extensions, the optional heap area following the main
data array (e.g. for variable length binary extensions).
OPTIONAL INPUT KEYWORDS:
/CHECKSUM - If set, then READFITS() will call FITS_TEST_CHECKSUM to
verify the data integrity if CHECKSUM keywords are present
in the FITS header. Cannot be used with the NSLICE, NUMROW
or STARTROW keywords, since verifying the checksum requires
that all the data be read. See FITS_TEST_CHECKSUM() for more
information.
/COMPRESS - Signal that the file is gzip compressed. By default,
READFITS will assume that if the file name extension ends in
'.gz' then the file is gzip compressed. The /COMPRESS keyword
is required only if the the gzip compressed file name does not
end in '.gz' or .ftz
EXTEN_NO - non-negative scalar integer specifying the FITS extension to
read. For example, specify EXTEN = 1 or /EXTEN to read the
first FITS extension.
/FPACK - Signal that the file is compressed with the FPACK software.
http://heasarc.gsfc.nasa.gov/fitsio/fpack/ ) By default,
(READFITS will assume that if the file name extension ends in
.fz that it is fpack compressed. The FPACK software must
be installed on the system
HBUFFER - Number of lines in the header, set this to slightly larger
than the expected number of lines in the FITS header, to
improve performance when reading very large FITS headers.
Should be a multiple of 36 -- otherwise it will be modified
to the next higher multiple of 36. Default is 180
/NOSCALE - If present and non-zero, then the ouput data will not be
scaled using the optional BSCALE and BZERO keywords in the
FITS header. Default is to scale.
/NO_UNSIGNED - By default, if the header indicates an unsigned integer
(BITPIX = 16, BZERO=2^15, BSCALE=1) then READFITS() will output
an IDL unsigned integer data type (UINT). But if /NO_UNSIGNED
is set, then the data is converted to type LONG.
NSLICE - An integer scalar specifying which N-1 dimensional slice of a
N-dimensional array to read. For example, if the primary
image of a file 'wfpc.fits' contains a 800 x 800 x 4 array,
then
IDL> im = readfits('wfpc.fits',h, nslice=2)
is equivalent to
IDL> im = readfits('wfpc.fits',h)
IDL> im = im[*,*,2]
but the use of the NSLICE keyword is much more efficient.
Note that any degenerate dimensions are ignored, so that the
above code would also work with a 800 x 800 x 4 x 1 array.
NUMROW - Scalar non-negative integer specifying the number of rows
of the image or table extension to read. Useful when one
does not want to read the entire image or table.
POINT_LUN - Position (in bytes) in the FITS file at which to start
reading. Useful if READFITS is called by another procedure
which needs to directly read a FITS extension. Should
always be a multiple of 2880, and not be used with EXTEN_NO
keyword.
/SILENT - Normally, READFITS will display the size the array at the
terminal. The SILENT keyword will suppress this
STARTROW - Non-negative integer scalar specifying the row
of the image or extension table at which to begin reading.
Useful when one does not want to read the entire table.
NaNVALUE - This keyword is included only for backwards compatibility
with routines that require IEEE "not a number" values to be
converted to a regular value.
/UNIXPIPE - When a FileUnit is supplied to READFITS(), then /UNIXPIPE
indicates that the unit is to a Unix pipe, and that
no automatic byte swapping is performed.
EXAMPLE:
Read a FITS file test.fits into an IDL image array, IM and FITS
header array, H. Do not scale the data with BSCALE and BZERO.
IDL> im = READFITS( 'test.fits', h, /NOSCALE)
If the file contains a FITS extension, it could be read with
IDL> tab = READFITS( 'test.fits', htab, /EXTEN )
The function TBGET() can be used for further processing of a binary
table, and FTGET() for an ASCII table.
To read only rows 100-149 of the FITS extension,
IDL> tab = READFITS( 'test.fits', htab, /EXTEN,
STARTR=100, NUMR = 50 )
To read in a file that has been compressed:
IDL> tab = READFITS('test.fits.gz',h)
ERROR HANDLING:
If an error is encountered reading the FITS file, then
(1) the system variable !ERROR_STATE.CODE is set negative
(via the MESSAGE facility)
(2) the error message is displayed (unless /SILENT is set),
and the message is also stored in !!ERROR_STATE.MSG
(3) READFITS returns with a value of -1
RESTRICTIONS:
(1) Cannot handle random group FITS
NOTES:
(1) If data is stored as integer (BITPIX = 16 or 32), and BSCALE
and/or BZERO keywords are present, then the output array is scaled to
floating point (unless /NOSCALE is present) using the values of BSCALE
and BZERO. In the header, the values of BSCALE and BZERO are then
reset to 1. and 0., while the original values are written into the
new keywords O_BSCALE and O_BZERO. If the BLANK keyword was
present (giving the value of undefined elements *prior* to the
application of BZERO and BSCALE) then the *keyword* value will be
updated with the values of BZERO and BSCALE.
(2) The use of the NSLICE keyword is incompatible with the NUMROW
or STARTROW keywords.
(3) On some Unix shells, one may get a "Broken pipe" message if reading
a Unix compressed (.Z) file, and not reading to the end of the file
(i.e. the decompression has not gone to completion). This is an
informative message only, and should not affect the output of READFITS.
PROCEDURES USED:
Functions: SXPAR()
Procedures: MRD_SKIP, SXADDPAR, SXDELPAR
MODIFICATION HISTORY:
Original Version written in 1988, W.B. Landsman Raytheon STX
Revision History prior to October 1998 removed
Major rewrite to eliminate recursive calls when reading extensions
W.B. Landsman Raytheon STX October 1998
Add /binary modifier needed for Windows W. Landsman April 1999
Read unsigned datatypes, added /no_unsigned W. Landsman December 1999
Output BZERO = 0 for unsigned data types W. Landsman January 2000
Update to V5.3 (see notes) W. Landsman February 2000
Fixed logic error in use of NSLICE keyword W. Landsman March 2000
Fixed byte swapping for Unix compress files on little endian machines
W. Landsman April 2000
Added COMPRESS keyword, catch IO errors W. Landsman September 2000
Option to read a unit number rather than file name W.L October 2001
Fix undefined variable problem if unit number supplied W.L. August 2002
Don't read entire header unless needed W. Landsman Jan. 2003
Added HBUFFER keyword W. Landsman Feb. 2003
Added CHECKSUM keyword W. Landsman May 2003
Restored NaNVALUE keyword for backwards compatibility,
William Thompson, 16-Aug-2004, GSFC
Recognize .ftz extension as compressed W. Landsman September 2004
Fix unsigned integer problem introduced Sep 2004 W. Landsman Feb 2005
Don't modify header for unsigned integers, preserve double precision
BSCALE value W. Landsman March 2006
Use gzip instead of compress for Unix compress files W.Landsman Sep 2006
Call MRD_SKIP to skip bytes on different file types W. Landsman Oct 2006
Make ndata 64bit for very large files E. Hivon/W. Landsman May 2007
Fixed bug introduced March 2006 in applying Bzero C. Magri/W.L. Aug 2007
Check possible 32bit overflow when using NSKIP W. Landsman Mar 2008
Always reset BSCALE, BZERO even for unsigned integers W. Landsman May 2008
Make ndata 64bit for very large extensions J. Schou/W. Landsman Jan 2009
Use PRODUCT() to compute # of data points W. Landsman May 2009
Read FPACK compressed file via UNIX pipe. W. Landsman May 2009
Fix error using NUMROW,STARTROW with non-byte data, allow these
keywords to be used with primary array W. Landsman July 2009
Ignore degenerate trailing dimensions with NSLICE keyword W.L. Oct 2009
Add DIALOG_PICKFILE() if filename is an empty string W.L. Apr 2010
Set BLANK values *before* applying BSCALE,BZERO, use short-circuit
operators W.L. May 2010
Skip extra SPAWN with FPACK decompress J. Eastman, W.L. July 2010
Fix possible problem when startrow=0 supplied J. Eastman/W.L. Aug 2010
First header is not necessarily primary if unit supplied WL Jan 2011
Fix test for 'SIMPLE' at beginning of header WL November 2012
(See astrolib/pro/readfits.pro)
READFMT
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NAME:
READFMT
PURPOSE:
Quickly read a fixed format ASCII data file into IDL variables.
EXPLANATION:
Lines of data not meeting the specified format (e.g. comments) are
ignored.
To read a free format ASCII data file use the procedures
READCOL or RDFLOAT. To print (formatted or free) columns of data
use the procedure FORPRINT.
CALLING SEQUENCE:
READFMT, name, fmt, v1,[ v2, v3, v4, ..., v25 ,
/SILENT, /DEBUG, SKIPLINE= , NUMLINE =]
INPUTS:
NAME - Name of ASCII data file. An extension of .DAT is assumed,
if not supplied.
FMT - scalar string containing a valid FORTRAN read format.
Must include a field length specification. Cannot include
internal parenthesis. A format field must be included for
each output vector. Multiple format fields are allowed, but
the repetition factor must be less than 100, (.i.e. 19X is
allowed but 117X is illegal)
Examples of valid FMT values are
FMT = 'A7,3X,2I4' or FMT = '1H ,5I7,2A7'
Examples of INVALID FMT values are
FMT = 'A7,B3' ;'B' is not a valid FORTRAN format
FMT = 'A7,2(I3,F5.1)' ;Internal parenthesis not allowed
FMT = 'A7,F,I' ;Field length not included
OUTPUTS:
V1,V2,V3,V4... - IDL vectors to contain columns of data.
Up to 25 output vectors may be read. The type of the output
vectors are specified by FMT.
OPTIONAL KEYWORD INPUTS:
/SILENT - If this keyword is set and non-zero, then certain terminal
output is suppressed while reading the file
/DEBUG - Set this keyword to display additional information while
reading the file.
SKIPLINE - Scalar specifying number of lines to skip at the top of
file before reading. Default is to start at first line
NUMLINE - Scalar specifying number of lines in the file to read.
Default is to read the entire file
EXAMPLES:
Each row in a fixed-format file POSITION.DAT contains a 5 character
star name and 6 columns of data giving an RA and Dec in sexagesimal
format. A possible format for such data might be
IDL> FMT = 'A5,2I3,F5.1,2x,3I3'
and the file could be quickly read with
IDL> READFMT,'POSITION', fmt, name, hr, min, sec, deg, dmin, dsec
NAME will be a string vector,SEC will be a floating point vector, and
the other vectors will be of integer type.
RESTRICTIONS:
This procedure is designed for generality and not for speed.
If a large ASCII file is to be read repeatedly, it may be worth
writing a specialized reader.
NOTES:
When reading a field with an integer format I, the output vector is
byte - if n = 1
integer*2 - if 1 < n < 5
integer*4 - in all other cases
Octal ('O') and hexadecimal ('Z') formats are read into longwords
PROCEDURE CALLS:
GETTOK(), REMCHAR, ZPARCHECK
REVISION HISTORY:
Written W. Landsman November, 1988
Added SKIPLINE and NUMLINE keywords March 92
Allow up to 25 columns to be read June 92
Call NUMLINES() function Feb 1996
Recognize 'O' and 'Z' formats W. Landsman September 1997
Recognize 'G' format, use SKIP_LUN W. Landsman May 2010
(See astrolib/pro/readfmt.pro)
READ_FMR
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NAME:
READ_FMR
PURPOSE:
Read a journal (ApJ, AJ) machine-readable table into IDL
EXPLANATION:
Given a machine readable table name and optionally column
numbers, this FUNCTION reads the format information in the
meta-header and outputs a IDL function containing either the
complete table or only the requested columns.
CALLING SEQUENCE:
data = read_fmr(filename)
INPUTS:
filename [STRING]: the name of the file containing the machine
readable table. If filename is missing a dialog to select the
filename will be presented
INPUT KEYWORD PARAMETERS:
/HELP - if set show the help
COLUMNS - [(array of) integers or strings] of column(s) to be returned.
If columns is of type integer they represent indices for which
column numbers to return, if they are strings the columns with the
corresponding names will be returned in the order as given.
MISSINGVALUE [float]: value with which to replace the missing values in the
table, default is NaN.
/USE_COLNUM - If specified and non-zero then column names will be generated
as 'C1, C2, .... Cn' for the number of columns in the table, rather
than using the table names.
OUTPUTS:
The ouput data structure will look like:
TYPE STRING 'mr_structure'
NAME STRING Array[X]
UNIT STRING Array[X]
DESCRIPTION STRING Array[X]
DATA STRUCT -> Array[1]
where name contains the names of each columns
unit contains the given units
description contains the short descriptions and
data holds the values of the separate columns. By default the tag names are
taken from the column names, with modifications necessary to make them a
valid tag name. For example, the column name 'B-V' will be converted to
'B_V' to become a valid tag name. If the /USE_COLNUM keyword is set, then
the column will be named C0, C1, ... , CX, where X stands for the total
number of columns read.
RESTRICTIONS:
(1) The file to be read should be formatted as a machine readable datafile.
(2) Use of the COLUMN keyword currently requires use of the EXECUTE, and so
cannot be used with the IDL Virtural machine.
EXAMPLE:
meas = read_fmr('smith.dat',col=[2,5,6], /Use_colnum)
plot,meas.data.c1,ytitle=meas.name[1]+' ('+meas.unit[1]+')'
and
data = read_fmr('smith.dat',col=['Name','Date'], /Use_colnum)
print,meas.data.c0
MODIFICATION HISTORY:
Version 1:
Written by Sacha Hony (ESA) Nov 14 2003
Based heavily on mrcolextract by Greg Schwarz (AAS Journals
staff scientist) on 8/16/00.
Version 1.1:
Fixed bug where column=[3,4] always returned the first few columns
VErsion 2.0 By default use column names as tag names W. Landsman Feb 2010
(See astrolib/pro/read_fmr.pro)
READ_KEY
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NAME:
READ_KEY
PURPOSE:
To read a keystroke and return its ASCII equivalent
EXPLANATION:
If an ESCAPE sequence was produced and the sequence is
recognized (e.g. up arrow), then a code is returned.
This functionality is mostly made obsolete by the addition of the
ESCAPE and KEY_NAME keywords to GET_KBRD in IDL V6.2
CALLING SEQUENCE:
key = READ_KEY(Wait)
INPUTS:
Wait - The wait flag. If non-zero, execution is halted until a
key is struck. If zero, execution returns immediately and
a zero is returned if there was no keystroke waiting in the
keyboard buffer. If not specified, zero is assumed.
OUTPUT:
Returned - The key struck. The ASCII code for non-escape sequences.
Escape sequence equivalents:
Up Arrow -- 128
Down Arrow -- 130
Left Arrow -- 129
Right Arrow -- 131
Else -- 0
The return value is a byte value.
MODIFICATION HISTORY:
Written by Michael R. Greason, STX, 22 June 1990.
Rewritten for a SUN workstation. MRG, STX, 23 August 1990.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/read_key.pro)
REMCHAR
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NAME:
REMCHAR
PURPOSE:
Remove all appearances of character (char) from string (st)
CALLING SEQUENCE:
REMCHAR, ST, CHAR
INPUT-OUTPUT:
ST - String from which character will be removed, scalar or vector
INPUT:
CHAR- Single character to be removed from string or all elements of a
string array
EXAMPLE:
If a = 'a,b,c,d,e,f,g' then
IDL> remchar,a, ','
will give a = 'abcdefg'
REVISIONS HISTORY
Written D. Lindler October 1986
Test if empty string needs to be returned W. Landsman Feb 1991
Work on string arrays W. Landsman August 1997
Avoid 32 bit integer overflow K. Tolbert/W. Landsman Feb 2007
(See astrolib/pro/remchar.pro)
REMOVE
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NAME:
REMOVE
PURPOSE:
Contract a vector or up to 25 vectors by removing specified elements
CALLING SEQUENCE:
REMOVE, index, v1,[ v2, v3, v4, v5, v6, ... v25]
INPUTS:
INDEX - scalar or vector giving the index number of elements to
be removed from vectors. Duplicate entries in index are
ignored. An error will occur if one attempts to remove
all the elements of a vector. REMOVE will return quietly
(no error message) if index is !NULL or undefined.
INPUT-OUTPUT:
v1 - Vector or array. Elements specifed by INDEX will be
removed from v1. Upon return v1 will contain
N fewer elements, where N is the number of distinct values in
INDEX.
OPTIONAL INPUT-OUTPUTS:
v2,v3,...v25 - additional vectors containing
the same number of elements as v1. These will be
contracted in the same manner as v1.
EXAMPLES:
(1) If INDEX = [2,4,6,4] and V = [1,3,4,3,2,5,7,3] then after the call
IDL> remove,index,v
V will contain the values [1,3,3,5,3]
(2) Suppose one has a wavelength vector W, and three associated flux
vectors F1, F2, and F3. Remove all points where a quality vector,
EPS is negative
IDL> bad = where( EPS LT 0, Nbad)
IDL> if Nbad GT 0 then remove, bad, w, f1, f2, f3
METHOD:
If more than one element is to be removed, then HISTOGRAM is used
to generate a 'keep' subscripting vector. To minimize the length of
the subscripting vector, it is only computed between the minimum and
maximum values of the index. Therefore, the slowest case of REMOVE
is when both the first and last element are removed.
REVISION HISTORY:
Written W. Landsman ST Systems Co. April 28, 1988
Cleaned up code W. Landsman September, 1992
Major rewrite for improved speed W. Landsman April 2000
Accept up to 25 variables, use SCOPE_VARFETCH internally
W. Landsman Feb 2010
Fix occasional integer overflow problem V. Geers Feb 2011
Quietly return if index is !null or undefined W.L. Aug 2011
(See astrolib/pro/remove.pro)
REM_DUP
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NAME:
REM_DUP
PURPOSE:
Function to remove duplicate values from a vector.
CALLING SEQUENCE:
result = rem_dup( a, [ flag ] )
INPUTS:
a - vector of values from which duplicates are to be found
flag - (optional) if supplied then when duplicates occur,
the one with the largest value of flag is selected.
If not supplied the the first occurence of the value
in a is selected. Should be a vector with the same
number of elements as a.
OUTPUT:
A vector of subscripts in a is returned. Each subscript
points to a selected value such that a(rem_dup(a,flag))
has no duplicates.
SIDE EFFECTS:
The returned subscripts will sort the values in a in ascending
order with duplicates removed.
EXAMPLES:
Remove duplicate values in vector a.
a = a[ rem_dup(a)]
Remove duplicates in vector WAVE. When duplicate values
are found, select the one with the largest intensity, INTE.
sub = rem_dup( wave, inte)
wave = wave[sub]
inte = inte[sub]
NOTES:
The UNIQ function in the User's Library uses a faster algorithm,
but has no equivalent of the "flag" parameter. Also, note that
REM_DUP() gives the index of the *first* equal value found, while
UNIQ() gives the index of the *last* equal value found.
MODIFICATION HISTORY:
D. Lindler Mar. 87
11/16/90 JKF ACC - converted to IDL Version 2.
August 1997 -- Changed loop index to type LONG
October 1997 -- Also changed NGOOD index to LONG
April 2007 - Use faster algorithm when Flag vector not set, W. Landsman
Feb 2011 - Remove spurious line W.L.
Jan 2012 - Call BSORT() to ensure original order maintained for equal
values
(See astrolib/pro/rem_dup.pro)
REPSTR
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NAME:
REPSTR
PURPOSE:
Replace all occurences of one substring by another.
EXPLANATION:
Meant to emulate the string substitution capabilities of text editors
For a more sophisticated routine that allows regular expressions look
at MG_STRREPLACE()
http://docs.idldev.com/idllib/strings/mg_streplace.html
CALLING SEQUENCE:
result = repstr( obj, in, out )
INPUT PARAMETERS:
obj = object string for editing, scalar or array
in = substring of 'obj' to be replaced, scalar
OPTIONAL INPUT PARMETER:
out = what 'in' is replaced with, scalar. If not supplied
then out = '', i.e. 'in' is not replaced by anything.
OUTPUT PARAMETERS:
Result returned as function value. Input object string
not changed unless assignment done in calling program.
PROCEDURE:
Searches for 'in', splits 'obj' into 3 pieces, reassembles
with 'out' in place of 'in'. Repeats until all cases done.
EXAMPLE:
If a = 'I am what I am' then print,repstr(a,'am','was')
will give 'I was what I was'.
MODIFICATION HISTORY:
Written by Robert S. Hill, ST Systems Corp., 12 April 1989.
Accept vector object strings, W. Landsman HSTX, April, 1996
Convert loop to LONG, vectorize STRLEN call W. Landsman June 2002
Correct bug in optimization, case where STRLEN(OBJ) EQ
STRLEN(IN), C. Markwardt, Jan 2003
Fixed problem when multiple replacements extend the string length
D. Finkbeiner, W. Landsman April 2003
Allow third parameter to be optional again W. Landsman August 2003
Remove limitation of 9999 characters, C. Markwardt Dec 2003
Test for empty "in" string (causing infinite loop) W. Landsman Jan 2010
Streamline code W Landsman Dec 2011
(See astrolib/pro/repstr.pro)
RESISTANT_MEAN
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NAME:
RESISTANT_Mean
PURPOSE:
Outlier-resistant determination of the mean and standard deviation.
EXPLANATION:
RESISTANT_Mean trims away outliers using the median and the median
absolute deviation. An approximation formula is used to correct for
the truncation caused by trimming away outliers
CALLING SEQUENCE:
RESISTANT_Mean, ARRAY, Sigma_CUT, Mean, Sigma_Mean, Num_RejECTED
[/DOUBLE, DIMENSION= , GOODVEC = ]
INPUT ARGUMENT:
ARRAY = Vector or array to average
Sigma_CUT = Data more than this number of standard deviations from the
median is ignored. Suggested values: 2.0 and up.
OUTPUT ARGUMENT:
Mean = the mean of the input array, numeric scalar, If the
DIMENSION keyword is set, then MEAN will be an array with one
less dimension than the input.
OPTIONAL OUTPUTS:
Sigma_Mean = the approximate standard deviation of the mean, numeric
scalar. This is the Sigma of the distribution divided by sqrt(N-1)
where N is the number of unrejected points. The larger
SIGMA_CUT, the more accurate. It will tend to underestimate the
true uncertainty of the mean, and this may become significant for
cuts of 2.0 or less.
Num_RejECTED = the number of points trimmed, integer scalar
OPTIONAL INPUT KEYWORDS:
/DOUBLE - If set, then all calculations are performed internally
in double precision.
DIMENSION - for a multi-dimensional array, the dimension over which to
take the mean, starting at 1. If not set, then the scalar mean
over all elements is used. If this argument is present, the result
is an array with one less dimension than Array. For example, if
the dimensions of Array are N1, N2, N3, and Dimension is 2, then
the dimensions of the result are (N1, N3)
SUMDIM - Obsolete synonym for DIMENSION
OPTIONAL OUTPUT KEYWORD:
Goodvec - Indices of non-trimmed elements of the input vector
Wused - synonym for Goodvec (for solarsoft compatibility)
EXAMPLE:
IDL> a = randomn(seed, 10000) ;Normal distribution with 10000 pts
IDL> RESISTANT_Mean,a, 3, mean, meansig, num ;3 Sigma clipping
IDL> print, mean, meansig,num
The mean should be near 0, and meansig should be near 0.01 ( =
1/sqrt(10000) ).
PROCEDURES USED:
MEAN() - compute simple mean, in Exelis library
REVISION HISTORY:
Written, H. Freudenreich, STX, 1989; Second iteration added 5/91.
Use MEDIAN(/EVEN) W. Landsman April 2002
Correct conditional test, higher order truncation correction formula
R. Arendt/W. Landsman June 2002
New truncation formula for sigma H. Freudenriech July 2002
Divide Sigma_mean by Num_good rather than Npts W. Landsman/A. Conley
January 2006
Use of double precision S. Bianchi February 2008
More double precision B. Carcich December 2009
Added DIMENSION keyword (from M. Desnoyer) B. Carcich December 2009
Use IDL's MEAN() function instead of AVG() W. Landsman Jan 2012
Use of Dimension keyword yielded transpose of correct value
W. Landsman July 2012
(See astrolib/pro/resistant_mean.pro)
RHOTHETA
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NAME:
RHOTHETA
PURPOSE:
Calculate the separation and position angle of a binary star
EXPLANATION:
This function will return the separation rho and position angle
theta of a visual binary star derived from its orbital elements.
The algorithms described in the following book will be used:
Meeus J., 1992, Astronomische Algorithmen, Barth.
Compared to the examples given at p. 400 and no discrepancy found.
Input parameters will never be changed.
CALLING SEQUENCE:
Result = RHOTHETA ( P, T, e, a, i, Omega, omega2, t2)
INPUT:
P - Period [year]
T - Time of periastron passage [year]
e - eccentricity of the orbit
a - semi-major axis [arc second]
i - inclination [degree]
Omega - node [degree]
omega2 - longitude of periastron [degree]
t2 - epoch of observation [year]
OUTPUT:
structure containing
rho - separation [arc second]
theta - position angle [degree]
In case of errors rho and theta are -1.
RESTRICTIONS:
All input parameters have to be scalars and floating point numbers.
EXAMPLE:
Find the position of Eta Coronae Borealis at the epoch 1980.0
IDL> test=rhotheta(41.623,1934.008,0.2763,0.907,59.025,23.717,219.907,1980.0)
rho= 0.411014 theta= 318.42307
PROCEDURES CALLED:
CIRRANGE - from IDL Astronomy Library
MODIFICATION HISTORY:
Written by: Sebastian Kohl Hamburg Observatory, November, 2012
(See astrolib/pro/rhotheta.pro)
RINTER
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NAME:
RINTER
PURPOSE:
Cubic interpolation of an image at a set of reference points.
EXPLANATION:
This interpolation program is equivalent to using the intrinsic
INTERPOLATE() function with CUBIC = -0.5. However,
RINTER() has two advantages: (1) one can optionally obtain the
X and Y derivatives at the reference points, and (2) if repeated
interpolation is to be applied to an array, then some values can
be pre-computed and stored in Common. RINTER() was originally
for use with the DAOPHOT procedures, but can also be used for
general cubic interpolation.
CALLING SEQUENCE:
Z = RINTER( P, X, Y, [ DFDX, DFDY ] )
or
Z = RINTER(P, /INIT)
INPUTS:
P - Two dimensional data array,
X - Either an N element vector or an N x M element array,
containing X subscripts where cubic interpolation is desired.
Y - Either an N element vector or an N x M element array,
containing Y subscripts where cubic interpolation is desired.
OUTPUT:
Z - Result = interpolated vector or array. If X and Y are vectors,
then so is Z, but if X and Y are arrays then Z will be also.
If P is DOUBLE precision, then so is Z, otherwise Z is REAL.
OPTIONAL OUTPUT:
DFDX - Vector or Array, (same size and type as Z), containing the
derivatives with respect to X
DFDY - Array containing derivatives with respect to Y
OPTIONAL KEYWORD INPUT:
/INIT - Perform computations associated only with the input array (i.e.
not with X and Y) and store in common. This can save time if
repeated calls to RINTER are made using the same array.
EXAMPLE:
suppose P is a 256 x 256 element array and X = FINDGEN(50)/2. + 100.
and Y = X. Then Z will be a 50 element array, containing the
cubic interpolated points.
SIDE EFFECTS:
can be time consuming.
RESTRICTION:
Interpolation is not possible at positions outside the range of
the array (including all negative subscripts), or within 2 pixel
units of the edge. No error message is given but values of the
output array are meaningless at these positions.
PROCEDURE:
invokes CUBIC interpolation algorithm to evaluate each element
in Z at virtual coordinates contained in X and Y with the data
in P.
COMMON BLOCKS:
If repeated interpolation of the same array is to occur, then
one can save time by initializing the common block RINTER.
REVISION HISTORY:
March 1988 written W. Landsman STX Co.
Checked for IDL Version 2, J. Isensee, September, 1990
Corrected call to HISTOGRAM, W. Landsman November 1990
Converted to IDL V5.0 W. Landsman September 1997
Fix output derivatives for 2-d inputs, added /INIT W. Landsman May 2000
(See astrolib/pro/rinter.pro)
ROBUST_LINEFIT
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NAME:
ROBUST_LINEFIT
PURPOSE:
An outlier-resistant two-variable linear regression.
EXPLANATION:
Either Y on X or, for the case in which there is no true independent
variable, the bisecting line of Y vs X and X vs Y is calculated. No
knowledge of the errors of the input points is assumed.
CALLING SEQUENCE:
COEFF = ROBUST_LINEFIT( X, Y, YFIT, SIG, COEF_SIG, [ /BISECT,
BiSquare_Limit = , Close_factor = , NumIT = ] )
INPUTS:
X = Independent variable vector, floating-point or double-precision
Y = Dependent variable vector
OUTPUTS:
Function result = coefficient vector.
If = 0.0 (scalar), no fit was possible.
If vector has more than 2 elements (the last=0) then the fit is dubious.
OPTIONAL OUTPUT PARAMETERS:
YFIT = Vector of calculated y's
SIG = The "standard deviation" of the fit's residuals. If BISECTOR
is set, this will be smaller by ~ sqrt(2).
COEF_SIG = The estimated standard deviations of the coefficients. If
BISECTOR is set, however, this becomes the vector of fit
residuals measured orthogonal to the line.
OPTIONAL INPUT KEYWORDS:
NUMIT = the number of iterations allowed. Default = 25
BISECT if set, the bisector of the "Y vs X" and "X vs Y" fits is
determined. The distance PERPENDICULAR to this line is used
in calculating weights. This is better when the uncertainties
in X and Y are comparable, so there is no true independent
variable. Bisquare_Limit Limit used for calculation of
bisquare weights. In units of outlier-resistant standard
deviations. Default: 6.
Smaller limit ==>more resistant, less efficient
Close_Factor - Factor used to determine when the calculation has converged.
Convergence if the computed standard deviation changes by less
than Close_Factor * ( uncertainty of the std dev of a normal
distribution ). Default: 0.03.
SUBROUTINE CALLS:
ROB_CHECKFIT
ROBUST_SIGMA, to calculate a robust analog to the std. deviation
PROCEDURE:
For the initial estimate, the data is sorted by X and broken into 2
groups. A line is fitted to the x and y medians of each group.
Bisquare ("Tukey's Biweight") weights are then calculated, using the
a limit of 6 outlier-resistant standard deviations.
This is done iteratively until the standard deviation changes by less
than CLOSE_ENOUGH = CLOSE_FACTOR * {uncertainty of the standard
deviation of a normal distribution}
REVISION HISTORY:
Written, H. Freudenreich, STX, 4/91.
4/13/93 to return more realistic SS's HF
2/94 --more error-checking, changed convergence criterion HF
5/94 --added BISECT option. HF.
8/94 --added Close_Factor and Bisquare_Limit options Jack Saba.
4/02 --V5.0 version, use MEDIAN(/EVEN) W. Landsman
(See astrolib/pro/robust_linefit.pro)
ROBUST_POLY_FIT
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NAME:
ROBUST_POLY_FIT
PURPOSE:
An outlier-resistant polynomial fit.
CALLING SEQUENCE:
COEFF = ROBUST_POLY_FIT(X,Y,NDEGREE, [ YFIT,SIG, /DOUBLE, NUMIT=] )
INPUTS:
X = Independent variable vector, floating-point or double-precision
Y = Dependent variable vector
NDEGREE - integer giving degree of polynomial to fit, maximum = 6
OUTPUTS:
Function result = coefficient vector, length NDEGREE+1.
IF COEFF=0.0, NO FIT! If N_ELEMENTS(COEFF) > degree+1, the fit is poor
(in this case the last element of COEFF=0.)
Either floating point or double precision.
OPTIONAL OUTPUT PARAMETERS:
YFIT = Vector of calculated y's
SIG = the "standard deviation" of the residuals
OPTIONAL INPUT KEYWORD:
/DOUBLE - If set, then force all computations to double precision.
NUMIT - Maximum number of iterations to perform, default = 25
RESTRICTIONS:
Large values of NDEGREE should be avoided. This routine works best
when the number of points >> NDEGREE.
PROCEDURE:
For the initial estimate, the data is sorted by X and broken into
NDEGREE+2 sets. The X,Y medians of each set are fitted to a polynomial
via POLY_FIT. Bisquare ("Tukey's Biweight") weights are then
calculated, using a limit of 6 outlier-resistant standard deviations.
The fit is repeated iteratively until the robust standard deviation of
the residuals changes by less than .03xSQRT(.5/(N-1)).
PROCEDURES CALLED:
POLY(), POLY_FIT()
ROB_CHECKFIT()
REVISION HISTORY
Written, H. Freudenreich, STX, 8/90. Revised 4/91.
2/94 -- changed convergence criterion
Added /DOUBLE keyword, remove POLYFITW call W. Landsman Jan 2009
(See astrolib/pro/robust_poly_fit.pro)
ROBUST_SIGMA
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NAME:
ROBUST_SIGMA
PURPOSE:
Calculate a resistant estimate of the dispersion of a distribution.
EXPLANATION:
For an uncontaminated distribution, this is identical to the standard
deviation.
CALLING SEQUENCE:
result = ROBUST_SIGMA( Y, [ /ZERO, GOODVEC = ] )
INPUT:
Y = Vector of quantity for which the dispersion is to be calculated
OPTIONAL INPUT KEYWORD:
/ZERO - if set, the dispersion is calculated w.r.t. 0.0 rather than the
central value of the vector. If Y is a vector of residuals, this
should be set.
OPTIONAL OUPTUT KEYWORD:
GOODVEC = Vector of non-trimmed indices of the input vector
OUTPUT:
ROBUST_SIGMA returns the dispersion. In case of failure, returns
value of -1.0
PROCEDURE:
Use the median absolute deviation as the initial estimate, then weight
points using Tukey's Biweight. See, for example, "Understanding Robust
and Exploratory Data Analysis," by Hoaglin, Mosteller and Tukey, John
Wiley & Sons, 1983, or equation 9 in Beers et al. (1990, AJ, 100, 32)
REVSION HISTORY:
H. Freudenreich, STX, 8/90
Replace MED() call with MEDIAN(/EVEN) W. Landsman December 2001
Don't count NaN values W.Landsman June 2010
(See astrolib/pro/robust_sigma.pro)
ROB_CHECKFIT
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NAME:
ROB_CHECKFIT
PURPOSE:
Used by ROBUST_... routines to determine the quality of a fit and to
return biweights.
CALLING SEQUENCE:
status = ROB_CHECKFIT( Y, YFIT, EPS, DEL, SIG, FRACDEV, NGOOD, W, B
BISQUARE_LIMIT = )
INPUT:
Y = the data
YFIT = the fit to the data
EPS = the "too small" limit
DEL = the "close enough" for the fractional median abs. deviations
RETURNS:
Integer status. if =1, the fit is considered to have converged
OUTPUTS:
SIG = robust standard deviation analog
FRACDEV = the fractional median absolute deviation of the residuals
NGOOD = the number of input point given non-zero weight in the
calculation
W = the bisquare weights of Y
B = residuals scaled by sigma
OPTIONAL INPUT KEYWORD:
BISQUARE_LIMIT = allows changing the bisquare weight limit from
default 6.0
PROCEDURES USED:
ROBUST_SIGMA()
REVISION HISTORY:
Written, H.T. Freudenreich, HSTX, 1/94
(See astrolib/pro/rob_checkfit.pro)
SELECT_W
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NAME:
SELECT_W
PURPOSE:
Create a non-exclusive widget menu of items
EXPLANATION:
More than one item may be selected or 'de-selected'.
Normally called by SCREEN_SELECT
CALLING SEQUENCE:
SELECT_W, items ,iselected, [ comments, command_line, only_one ]
INPUTS:
items - string array giving list of items that can be
selected.
OPTIONAL INPUTS:
comments - comments which can be requested for each item in
array selections. NOT YET IMPLEMENTED
command_line - optional command line to be placed at the bottom
of the screen. It is usually used to specify what the
user is selecting.
only_one - integer flag. If set to 1 then the user can only select
one item. The routine returns immediately after the first
selection is made.
OPTIONAL KEYWORD INPUT
SELECTIN - vector of items to be pre-selected upon input (not used for
only_one option)
OUTPUT:
iselected - list of indices in selections giving the selected
items.
OPTIONAL OUTPUT KEYWORD:
COUNT - Integer scalar giving the number of items selected
COMMON BLOCKS:
SELECT_W - Used to communicate with the SELECT_W_EVENT procedure
MODIFICATION HISTORY:
Written, K. Venkatakrishna & W. Landsman, Hughes/STX January, 1992
Widgets made MODAL. M. Greason, Hughes STX, 15 July 1992.
Changed handling of MODAL keyword for V5.0 W.Thompson September 1997
Added selectin keyword D. Lindler 01/12/99
(See astrolib/pro/select_w.pro)
SIGMA_FILTER
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NAME:
SIGMA_FILTER
PURPOSE:
Replace pixels more than a specified pixels deviant from its neighbors
EXPLANATION:
Computes the mean and standard deviation of pixels in a box centered at
each pixel of the image, but excluding the center pixel. If the center
pixel value exceeds some # of standard deviations from the mean, it is
replaced by the mean in box. Note option to process pixels on the edges.
CALLING SEQUENCE:
Result = sigma_filter( image, box_width, N_sigma=(#), /ALL,/MON )
INPUTS:
image = 2-D image (matrix)
box_width = width of square filter box, in # pixels (default = 3)
KEYWORDS:
N_sigma = # standard deviations to define outliers, floating point,
recommend > 2, default = 3. For gaussian statistics:
N_sigma = 1 smooths 35% of pixels, 2 = 5%, 3 = 1%.
RADIUS = alternative to specify box radius, so box_width = 2*radius+1.
/ALL_PIXELS causes computation to include edges of image,
/KEEP causes opposite effect: pixels with values outside of specified
deviation are not changed, pixels within deviation are smoothed.
/ITERATE causes sigma_filter to be applied recursively (max = 20 times)
until no more pixels change (only allowed when N_sigma >= 2).
/MONITOR prints information about % pixels replaced.
Optional Outputs:
N_CHANGE = # of pixels changed (replaced with neighborhood mean).
VARIANCE = image of pixel neighborhood variances * (N_sigma)^2,
DEVIATION = image of pixel deviations from neighborhood means, squared.
CALLS:
function filter_image( )
PROCEDURE:
Compute mean over moving box-cars using smooth, subtract center values,
compute variance using smooth on deviations from mean,
check where pixel deviation from mean is within variance of box,
replace those pixels in smoothed image (mean) with orignal values,
return the resulting partial mean image.
MODIFICATION HISTORY:
Written, 1991, Frank Varosi and Dan Gezari NASA/GSFC
F.V.1992, added optional keywords /ITER,/MON,VAR=,DEV=,N_CHANGE=.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/sigma_filter.pro)
SIGRANGE()
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NAME:
SIGRANGE()
PURPOSE:
Selects the most significant data range in an image.
EXPLANATION:
Selects out the most significant range in the data to be used in
displaying images. The histogram of ARRAY is used to select the most
significant range. Useful for scaling an image display.
CALLING SEQUENCE:
OUTPUT = SIGRANGE( ARRAY )
INPUTS:
ARRAY = Array to take most significant range of.
OPTIONAL INPUTS:
None.
OUTPUTS:
The function returns an array where values above and below the
selected range are set equal to the maximum and minimum of the
range respectively.
OPTIONAL INPUT KEYWORDS:
FRACTION = Fraction of data to consider most significant.
Defaults to 0.99
MISSING = Value used to flag missing points. Data points with this
value are not considered or changed.
OPTIONAL OUTPUT KEYWORD
RANGE = 2 element vector, giving the range (minimum and maxmimum)
used
NOTES:
If the image array contains more than 10,000 points then SIGRANGE()
uses random indexing of a subset of the points to determine the range
(for speed). Thus identical calls to SIGRANGE() might not yield
identical results (although they should be very close).
RESTRICTIONS:
ARRAY must have more than two points. Fraction must be greater than 0
and less than 1.
SIGRANGE was originally part of the SERTS image display package.
Other routines from this package are available at
http://sohowww.nascom.nasa.gov/solarsoft/gen/idl/image/
Note that this version of SIGRANGE does not include the non-standard
system variables used in the SERTS package.
REVISION HISTORY:
Version 1, William Thompson, GSFC, 12 May 1993.
Incorporated into CDS library.
Version 2, William Thompson, GSFC, 25 May 1993.
Changed call to HISTOGRAM to be compatible with OpenVMS/ALPHA
Version 3, CDP, RAL, Add RANGE keyword. 16-Apr-96
Version 4, William Thompson, GSFC, 17 April 1996
Corrected some problems when range is too high.
Version 5, 13-Jan-1998, William Thompson, GSFC
Use random numbers to improve statistics when only using a
fraction of the array.
Version 6, 06-Mar-1998, William Thompson, GSFC
Change default to 0.99
(See astrolib/pro/sigrange.pro)
SIXLIN
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NAME:
SIXLIN
PURPOSE:
Compute linear regression coefficients by six different methods.
EXPLANATION:
Adapted from the FORTRAN program (Rev. 1.1) supplied by Isobe,
Feigelson, Akritas, and Babu Ap. J. Vol. 364, p. 104 (1990).
Suggested when there is no understanding about the nature of the
scatter about a linear relation, and NOT when the errors in the
variable are calculable.
CALLING SEQUENCE:
SIXLIN, xx, yy, a, siga, b, sigb, [WEIGHT = ]
INPUTS:
XX - vector of X values
YY - vector of Y values, same number of elements as XX
OUTPUTS:
A - Vector of 6 Y intercept coefficients
SIGA - Vector of standard deviations of 6 Y intercepts
B - Vector of 6 slope coefficients
SIGB - Vector of standard deviations of slope coefficients
The output variables are computed using linear regression for each of
the following 6 cases:
(0) Ordinary Least Squares (OLS) Y vs. X (c.f. linfit.pro)
(1) Ordinary Least Squares X vs. Y
(2) Ordinary Least Squares Bisector
(3) Orthogonal Reduced Major Axis
(4) Reduced Major-Axis
(5) Mean ordinary Least Squares
OPTIONAL INPUT KEYWORD:
WEIGHT - vector of weights, same number of elements as XX and YY
For 1 sigma Gausssian errors, the weights are 1/sigma^2 but
the weight vector can be more general. Default is no
weighting.
NOTES:
Isobe et al. make the following recommendations
(1) If the different linear regression methods yield similar results
then quoting OLS(Y|X) is probably the most familiar.
(2) If the linear relation is to be used to predict Y vs. X then
OLS(Y|X) should be used.
(3) If the goal is to determine the functional relationship between
X and Y then the OLS bisector is recommended.
REVISION HISTORY:
Written Wayne Landsman February, 1991
Corrected sigma calculations February, 1992
Converted to IDL V5.0 W. Landsman September 1997
Added WEIGHT keyword J. Moustakas Februrary 2007
(See astrolib/pro/sixlin.pro)
SIXTY()
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NAME:
SIXTY()
PURPOSE:
Converts a decimal number to sexagesimal.
EXPLANATION:
Reverse of the TEN() function.
CALLING SEQUENCE:
X = SIXTY( SCALAR, [ /TrailSign ] )
INPUTS:
SCALAR -- Decimal quantity.
OUTPUTS:
Function value returned = real vector of three elements,
sexagesimal equivalent of input decimal quantity. Double
precision if the input is double, otherwise floating point.
By default, a negative number is signified by making the first non-zero
element of the output vection negative, but this can be modfied with
the /TrailSign keyword.
OPTIONAL INPUT KEYWORD:
/TrailSign - By default, SIXTY() returns a negative sign in the first
nonzero element. If /TrailSign is set, then SIXTY() will return
always return a negative sign in the first element, even if it is
zero
PROCEDURE:
Mostly involves checking arguments and setting the sign.
EXAMPLE:
If x = -0.345d then sixty(x) = [0.0, -20.0, 42.0]
and sixty(x,/trail) = [-0.0, 20.0, 42.0]
MODIFICATION HISTORY:
Written by R. S. Hill, STX, 19-OCT-87
Output changed to single precision. RSH, STX, 1/26/88
Accept single element vector W. Landsman Sep. 1996
Converted to IDL V5.0 W. Landsman September 1997
Added /TrailSign keyword, preserve data type
B. Stecklum/ W. Landsman March 2006
(See astrolib/pro/sixty.pro)
SKY
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NAME:
SKY
PURPOSE:
Determine the sky level in an image
EXPLANATION:
Approximately 10000 uniformly spaced pixels are selected for the
computation. Adapted from the DAOPHOT routine of the same name.
The sky is computed either by using the procedure mmm.pro (default)
or by sigma clipping (if /MEANBACK is set)
CALLING SEQUENCE:
SKY, image, [ skymode, skysig ,/SILENT, /MEANBACK, /NAN, CIRCLERAD= ]
Keywords available when MEANBACK is not set (passed to mmm.pro):
/DEBUG, HIGHBAD=, /INTEGER, MAXITER=. READNOISE=
Keywords available when /MEANBACK is set:
CLIPSIG=, /DOUBLE, CONVERGE_NUM=, MAXITER=, /VERBOSE
INPUTS:
IMAGE - One or two dimensional array
OPTIONAL OUTPUT ARRAYS:
SKYMODE - Scalar, giving the mode of the sky pixel values of the
array IMAGE, as determined by the procedures MMM or MEANCLIP
SKYSIG - Scalar, giving standard deviation of sky brightness. If it
was not possible to derive a mode then SKYSIG is set to -1
INPUT KEYWORD PARAMETERS:
CIRCLERAD - Use this keyword to have SKY only select pixels within
specified pixel radius of the center of the image. If
CIRCLERAD =1, then the radius is set equal to half the image
width. Can only be used with square images.
/MEANBACK - if set, then the background is computed using the 3 sigma
clipped mean (using meanclip.pro) rather than using the mode
computed with mmm.pro. This keyword is useful for the Poisson
count regime or where contamination is known to be minimal.
/NAN - This keyword must be set to ignore NaN values when computing
the sky.
/SILENT - If this keyword is supplied and non-zero, then SKY will not
display the sky value and sigma at the terminal
The _EXTRA facility can is used to pass optional keywords to the programs
that actually perform the sky computation: either mmm.pro
(default) or meanclip.pro (if /MEANBACK) is set. The following
keywords are available with the mmm.pro (default) setting
HIGHBAD - scalar value of the (lowest) "bad" pixel level (e.g. cosmic
rays or saturated pixels) If not supplied, then there is
assumed to be no high bad pixels.
READNOISE - Scalar giving the read noise (or minimum noise for any
pixel). Normally, MMM determines the (robust) median by
averaging the central 20% of the sky values. In some cases
where the noise is low, and pixel values are quantized a
larger fraction may be needed. By supplying the optional
read noise parameter, MMM is better able to adjust the
fraction of pixels used to determine the median.
/INTEGER - Set this keyword if the input SKY image only contains
discrete integer values. This keyword is only needed if the
SKY image is of type float or double precision, but contains
only discrete integer values.
If the /MEANBACK keyword is set then the following keywords are available
CLIPSIG: Number of sigma at which to clip. Default=3
MAXITER: Ceiling on number of clipping iterations. Default=5
CONVERGE_NUM: If the proportion of rejected pixels is less
than this fraction, the iterations stop. Default=0.02, i.e.,
iteration stops if fewer than 2% of pixels excluded.
/DOUBLE - if set then perform all computations in double precision.
Otherwise double precision is used only if the input
data is double
PROCEDURE:
A grid of points, not exceeding 10000 in number, is extracted
from the srray. The mode of these pixel values is determined
by the procedure mmm.pro or meanclip.pro. In a 2-d array the grid is
staggered in each row to avoid emphasizing possible bad columns
PROCEDURE CALLS:
MEANCLIP, MMM, DIST_CIRCLE
REVISION HISTORY:
Written, W. Landsman STX Co. September, 1987
Changed INDGEN to LINDGEN January, 1994
Fixed display of # of points used March, 1994
Stagger beginning pixel in each row, added NSKY, READNOISE, HIGHBAD
W. Landsman June 2004
Adjustments for unbiased sampling W. Landsman June 2004
Added /NAN keyword, put back CIRCLERAD keyword W. Landsman July 2004
Added MEANBACK keyword, _EXTRA kewyord ,preserve data type in
calculations W. Landsman November 2005
Fix problem for very large images by requiring at least 2 pixels to
be sampled per row. March 2007 W. Landsman
Avoid possible out of bounds if /NAN set W. Landsman Jan 2008
Use TOTAL(/INTEGER) June 2009
(See astrolib/pro/sky.pro)
SKYADJ_CUBE
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NAME:
SKYADJ_CUBE
PURPOSE:
Sky adjust the planes of a datacube.
EXPLANATION:
When removing cosmic rays from a set of images, it is desirable that
all images have the same sky level. This procedure (called by
CR_REJECT) removes the sky from each image in a data cube.
CALLING SEQUENCE:
SKYADJ_CUBE,Datacube,Skyvals,Totsky
MODIFIED ARGUMENT:
Datacube: 3-D array with one image of same field in each plane.
Returned with sky in each plane adjusted to zero.
OUTPUT ARGUMENTS:
Skyvals: Array of sky values used on each plane of datacube.
For a scalar sky, this parameter is a vector
containing the sky value for each image plane. For a
vector sky, this parameter is a 2-D array where each
line corresponds to one image plane.
INPUT KEYWORD PARAMETERS:
REGION - [X0,X1,Y0,Y1] to restrict area used for computation
of sky. Default is 0.1*Xdim, 0.9*Xdim, 0.1*Ydim,
0.9*Ydim. If INPUT_MASK is specified, the two
specs are combined, i.e., the intersection of the
areas is used.
VERBOSE - Flag. If set, print information on skyvals.
NOEDIT - Flag. If set, return sky values without changing
datacube.
XMEDSKY - Flag. If set, return vector sky as a function of X.
SELECT - Array of subscripts of planes of the cube to process.
(Default=all)
EXTRAPR - Applies only in XMEDSKY mode.
Subregion to use for polynomial extrapolation of sky
vector into portions excluded by REGION parameter.
(Default=first and last 10% of pixels; set to zero
to defeat extrapolation)
EDEGREE - Applies only in XMEDSKY mode.
Degree of polynomial for extrapolation (Default=1)
INPUT_MASK - Cube of flags corresponding to data cube. If used,
the sky computation is restricted to the smallest
contiguous rectangle containing all the pixels flagged
valid (with 1 rather than 0).
PROCEDURE:
Uses astronomy library "sky" routine for scalar sky and
column-by-column median for vector sky.
MODIFICATION HISTORY:
10 Jul. 1997 - Written. R. S. Hill, Hughes STX
20 Oct. 1997 - 1-D sky option. RSH
7 Aug. 1998 - SELECT keyword. RSH
6 Oct. 1998 - Extrapolation. RSH
7 Oct. 1998 - INPUT_MASK added. RSH
21 Oct. 1998 - Fallback to 3-sigma clipped mean if mode fails. RSH
22 Mar. 2000 - Combine mask with region rather having mask
override region. Improve comments. RSH
16 June 2000 - On_error and message used. Square brackets for array
subscripts. EXTRAP included in this file.
WBL & RSH, 16 June 2000
(See astrolib/pro/skyadj_cube.pro)
SPEC_DIR()
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NAME:
SPEC_DIR()
PURPOSE:
Complete a file specification by appending the default disk or directory
CALLING SEQUENCE:
File_spec = SPEC_DIR( filename, [ extension ] )
INPUT:
filename - character string giving partial specification of a file
name. Examples for different operating systems include the
following:
Unix: 'pro/test.dat', '$IDL_HOME/test','~/subpro'
MacOS: ':Programs:test'
Windows: '\pro\test.dat','d:\pro\test'
OPTIONAL INPUT:
exten - string giving a default file name extension to be used if
filename does not contain one. Do not include the period.
OUTPUT:
File_spec - Complete file specification using default disk or
directory when necessary.
EXAMPLE:
IDL> a = spec_dir('test','dat')
is equivalent to the commands
IDL> cd, current=cdir
IDL> a = cdir + delim + 'test.dat'
where delim is the OS-dependent separator
METHOD:
SPEC_DIR() decomposes the file name using FDECOMP, and appends the
default directory (obtained from the FILE_EXPAND_PATH) if necessary.
SPEC_DIR() does not check whether the constructed file name actually
exists.
PROCEDURES CALLED:
FDECOMP, EXPAND_TILDE()
REVISION HISTORY:
Written W. Landsman STX July, 1987
Expand Unix tilde if necessary W. Landsman September 1997
Assume since V5.5, use FILE_EXPAND_PATH, remove VMS support
W. Landsman September 2006
(See astrolib/pro/spec_dir.pro)
SRCOR
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NAME:
SRCOR
PURPOSE:
Correlate the source positions found on two lists.
EXPLANATION:
Source matching is done by finding sources within a specified radius.
If you have position errors available and wish to match by significance
level, then try match_xy.pro in the TARA library
(http://www.astro.psu.edu/xray/docs/TARA/)
CALLING SEQUENCE:
srcor,x1in,ylin,x2in,y2in,dcr,ind1,ind2,
[MAGNITUDE=,SPHERICAL=,COUNT=,/SILENT]
INPUTS:
x1in,y1in - First set of x and y coordinates. The program
marches through this list element by element,
looking in list 2 for the closest match. So, the program
will run faster if this is the shorter of the two lists.
Unless you use the option or magnitude keyword, there is
nothing to guarantee unique matches.
x2in,y2in - Second set of x and y coordinates. This list is
searched in its entirety every time one element of list 1
is processed.
dcr - Critical radius outside which correlations are rejected;
but see 'option' below.
OPTIONAL KEYWORD INPUT:
option - Changes behavior of program and description of output
lists slightly, as follows:
OPTION=0 or left out
Same as older versions of SRCOR. The closest match from list2
is found for each element of list 1, but if the distance is
greater than DCR, the match is thrown out. Thus the index
of that element within list 1 will not appear in the IND1 output
array.
OPTION=1
Forces the output mapping to be one-to-one. OPTION=0 results,
in general, in a many-to-one mapping from list 1 to list 2.
Under OPTION=1, a further processing step is performed to
keep only the minimum-distance match, whenever an entry from
list 1 appears more than once in the initial mapping.
OPTION=2
Same as OPTION=1, except the critical distance parameter DCR
is ignored. I.e., the closest object is retrieved from list 2
for each object in list 1 WITHOUT a critical-radius criterion,
then the clean-up of duplicates is done as under OPTION=1.
magnitude
An array of stellar magnitudes corresponding to x1in and y1in.
If this is supplied, then the brightest star from list 1
within the selected distance of the star in list 2 is taken.
The option keyword is ignored in this case.
spherical
If SPHERICAL=1, it is assumed that the input arrays are in
celestial coordinates (RA and Dec), with x1in and x2in in
decimal hours and y1in and y2in in decimal degrees. If
SPHERICAL=2 then it is assumed that the input arrays are in
longitude and latitude with x1in,x2in,y1in,y2in in decimal
degrees. In both cases, the critial radius dcr is in
*arcseconds*. Calculations of spherical distances are made
with the gcirc program.
OUTPUTS:
ind1 - index of matched stars in first list, set to -1 if no matches
found
ind2 - index of matched stars in second list
OPTIONAL OUTPUT KEYWORD:
Count - integer giving number of matches returned
PROCEDURES USED:
GCIRC, REMOVE
REVISON HISTORY:
Adapted from UIT procedure J.Wm.Parker, SwRI 29 July 1997
Improve speed for spherical searches, added /SILENT keyword
W. Landsman Mar 2009
Avoid error when no matches found with /SPHERICAL O. Trottier June 2009
Added output Count keyword W.L June 2009
Adjust right ascension for cosine angle W.L. December 2009
Return as soon as no matches found W.L. December 2009
Use some V6.0 notation W.L. February 2011
Fix problem when /Spherical and Option =2 set, and sources separated
by more han 180 degrees. W.L. March 2011
(See astrolib/pro/srcor.pro)
STARAST
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NAME:
STARAST
PURPOSE:
Compute astrometric solution using positions of 2 or 3 reference stars
EXPLANATION:
Computes an exact astrometric solution using the positions and
coordinates from 2 or 3 reference stars and assuming a tangent
(gnomonic) projection. If 2 stars are used, then
the X and Y plate scales are assumed to be identical, and the
axis are assumed to be orthogonal. Use of three stars will
allow a unique determination of each element of the CD matrix.
CALLING SEQUENCE:
starast, ra, dec, x, y, cd, [/Righthanded, HDR = h, PROJECTION=]
INPUTS:
RA - 2 or 3 element vector containing the Right Ascension in DEGREES
DEC- 2 or 3 element vector containing the Declination in DEGREES
X - 2 or 3 element vector giving the X position of reference stars
Y - 2 or 3 element vector giving the Y position of reference stars
OUTPUTS:
CD - CD (Coordinate Description) matrix (DEGREES/PIXEL) determined
from stellar positions and coordinates.
OPTIONAL INPUT KEYWORD:
/RightHanded - If only 2 stars are supplied, then there is an ambiguity
in the orientation of the coordinate system. By default,
STARAST assumes the astronomical standard left-handed system
(R.A. increase to the left). If /Right is set then a
righthanded coordinate is assumed. This keyword has no effect
if 3 star positions are supplied.
PROJECTION - Either a 3 letter scalar string giving the projection
type (e.g. 'TAN' or 'SIN') or an integer 1 - 25 specifying the
projection as given in the WCSSPH2XY procedure. If not
specified then a tangent projection is computed.
OPTIONAL INPUT-OUTPUT KEYWORD:
HDR - If a FITS header string array is supplied, then an astrometry
solution is added to the header using the CD matrix and star 0
as the reference pixel (see example). Equinox 2000 is assumed.
EXAMPLE:
To use STARAST to add astrometry to a FITS header H;
IDL> starast,ra,dec,x,y,cd ;Determine CD matrix
IDL> crval = [ra[0],dec[0]] ;Use Star 0 as reference star
IDL> crpix = [x[0],y[0]] +1 ;FITS is offset 1 pixel from IDL
IDL> putast,H,cd,crpix,crval ;Add parameters to header
This is equivalent to the following command:
IDL> STARAST,ra,dec,x,y,hdr=h
METHOD:
The CD parameters are determined by solving the linear set of equations
relating position to local coordinates (l,m)
For highest accuracy the first star position should be the one closest
to the reference pixel.
REVISION HISTORY:
Written, W. Landsman January 1988
Converted to IDL V5.0 W. Landsman September 1997
Added /RightHanded and HDR keywords W. Landsman September 2000
Write CTYPE values into header W. Landsman/A. Surkov December 2002
CD matrix was mistakenly transpose in 3 star solution
Added projection keyword W. Landsman September 2003
Test for singular matrix W. Landsman August 2011
(See astrolib/pro/starast.pro)
STORE_ARRAY
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NAME:
STORE_ARRAY
PURPOSE:
Insert array INSERT into the array DESTINATION
EXPLANATION:
The dimensions of the DESTINATION array are adjusted to accommodate
the inserted array.
CATEGOBY:
Utility
CALLING SEQUENCE:
STORE_ARRAY, DESTINATION, INSERT, INDEX
INPUT:
DESTINATION = Array to be expanded.
INSERT = Array to insert into DESTINATION.
INDEX = Index of the final dimension of DESTINATION to insert
INSERT into.
OUTPUTS:
DESTINATION = Expanded output array. If both input arrays have the
same number of dimensions, then the DESTINATION will
be replaced with INSERT.
RESTRICTIONS:
DESTINATION and INSERT have to be either both of type string or both of
numerical types.
INSERT must not have more dimensions than DESTINATION.
MODIFICATION HISTOBY:
William Thompson, Feb. 1992, from BOOST_ARRAY by D. Zarro and P. Hick.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/store_array.pro)
STRCOMPRESS2
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NAME:
STRCOMPRESS2
PURPOSE:
Remove blanks around specified characters in a string
CALLING SEQUENCE
newstring = strcompress2( st, chars)
INPUTS:
st - any scalar string
chars - scalar or vector string specifing which characters around which
blanks should be removed. For example, if chars=['=','-','+']
then spaces around the three characters "=', '-', and '+' will
be removed.
OUTPUTS:
newstring - input string with spaces removed around the specified
characters.
EXAMPLE:
The Vizier constraint string (see queryvizier.pro) does not allow
blanks around the operators '=','<', or '>'. But we do not want
to remove blanks around names (e.g. 'NGC 5342'):
IDL> st = 'name = NGC 5342, v< 23'
IDL> print,strcompress2(st, ['=','<','>'])
name=NGC 5342, v<23
MODIFICATION HISTORY:
Written by W.Landsman July 2008
(See astrolib/pro/strcompress2.pro)
STRN
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NAME:
STRN
PURPOSE:
Convert a number to a string and remove padded blanks.
EXPLANATION:
The main and original purpose of this procedure is to convert a number
to an unpadded string (i.e. with no blanks around it.) However, it
has been expanded to be a multi-purpose formatting tool. You may
specify a length for the output string; the returned string is either
set to that length or padded to be that length. You may specify
characters to be used in padding and which side to be padded. Finally,
you may also specify a format for the number. NOTE that the input
"number" need not be a number; it may be a string, or anything. It is
converted to string.
CALLING SEQEUNCE:
tmp = STRN( number, [ LENGTH=, PADTYPE=, PADCHAR=, FORMAT = ] )
INPUT:
NUMBER This is the input variable to be operated on. Traditionally,
it was a number, but it may be any scalar type.
OPTIONAL INPUT:
LENGTH This KEYWORD specifies the length of the returned string.
If the output would have been longer, it is truncated. If
the output would have been shorter, it is padded to the right
length.
PADTYPE This KEYWORD specifies the type of padding to be used, if any.
0=Padded at End, 1=Padded at front, 2=Centered (pad front/end)
IF not specified, PADTYPE=1
PADCHAR This KEYWORD specifies the character to be used when padding.
The default is a space (' ').
FORMAT This keyword allows the FORTRAN type formatting of the input
number (e.g. '(f6.2)')
OUTPUT:
tmp The formatted string
USEFUL EXAMPLES:
print,'Used ',strn(stars),' stars.' ==> 'Used 22 stars.'
print,'Attempted ',strn(ret,leng=6,padt=1,padch='0'),' retries.'
==> 'Attempted 000043 retries.'
print,strn('M81 Star List',length=80,padtype=2)
==> an 80 character line with 'M81 Star List' centered.
print,'Error: ',strn(err,format='(f15.2)')
==> 'Error: 3.24' or ==> 'Error: 323535.22'
HISTORY:
03-JUL-90 Version 1 written by Eric W. Deutsch
10-JUL-90 Trimming and padding options added (E. Deutsch)
29-JUL-91 Changed to keywords and header spiffed up (E. Deutsch)
Ma7 92 Work correctly for byte values (W. Landsman)
19-NOV-92 Added Patch to work around IDL 2.4.0 bug which caused an
error when STRN('(123)') was encountered. (E. Deutsch)
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/strn.pro)
STRNUMBER()
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NAME:
STRNUMBER()
PURPOSE:
Function to determine if a string is a valid numeric value.
EXPLANATION:
A string is considered a valid numeric value if IDL can convert it
to a numeric variable without error.
CALLING SEQUENCE:
result = strnumber( st, [val, /HEX] )
INPUTS:
st - any IDL scalar string
OUTPUTS:
1 is returned as the function value if the string st has a
valid numeric value, otherwise, 0 is returned.
OPTIONAL OUTPUT:
val - (optional) value of the string. double precision unless /L64 is set
OPTIONAL INPUT KEYWORD:
/HEX - If present and nonzero, the string is treated as a hexadecimal
longword integer.
/L64 - If present and nonzero, the val output variable is returned
as a 64 bit integer. This to ensure that precision is not
lost when returning a large 64 bit integer as double precision.
This keyword has no effect on the function result.
/NAN - if set, then the value of an empty string is returned as NaN,
by default the returned value is 0.0d. In either case,
an empty string is considered a valid numeric value.
EXAMPLES:
IDL> res = strnumber('0.2d', val)
returns res=1 (a valid number), and val = 0.2000d
NOTES:
(1) STRNUMBER was modified in August 2006 so that an empty string is
considered a valid number. Earlier versions of strnumber.pro did not
do this because in very early (pre-V4.0) versions of IDL
this could corrupt the IDL session.
(2) STRNUMBER will return a string such as '23.45uyrg' as a valid
number (=23.45) since this is how IDL performs the type conversion. If
you want a stricter definition of valid number then use the VALID_NUM()
function.
HISTORY:
version 1 By D. Lindler Aug. 1987
test for empty string, W. Landsman February, 1993
Hex keyword added. MRG, RITSS, 15 March 2000.
An empty string is a valid number W. Landsman August 2006
Added /NAN keyword W. Landsman August 2006
Added /L64 keyword W. Landsman Feb 2010
(See astrolib/pro/strnumber.pro)
STR_INDEX()
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NAME:
STR_INDEX()
PURPOSE:
Get indices of a substring (SUBSTR) in string.
EXPLANATION:
The IDL intrinsic function STRPOS returns only the index of the first
occurrence of a substring. This routine calls itself recursively to get
indices of the remaining occurrences.
CALLING SEQUENCE:
result= STR_INDEX(str, substr [, offset])
INPUTS:
STR -- The string in which the substring is searched for
SUBSTR -- The substring to be searched for within STR
OPTIONAL INPUTS:
OFFSET -- The character position at which the search is begun. If
omitted or being negative, the search begins at the first
character (character position 0).
OUTPUTS:
RESULT -- Integer scalar or vector containing the indices of SUBSTR
within STR. If no substring is found, it is -1.
CALLS:
DELVARX
COMMON BLOCKS:
STR_INDEX -- internal common block. The variable save in the block is
deleted upon final exit of this routine.
CATEGORY:
Utility, string
MODIFICATION HISTORY:
Written January 3, 1995, Liyun Wang, GSFC/ARC
Converted to IDL V5.0 W. Landsman September 1997
Use size(/TNAME) instead of DATATYPE() W. Landsman October 2001
(See astrolib/pro/str_index.pro)
ST_DISKREAD
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NAME:
ST_DISKREAD
PURPOSE:
Read HST FITS formatted disk files and reconstruct GEIS (STSDAS) files.
CALLING SEQUENCE:
ST_DISKREAD, infiles
INPUT PARAMETER:
infiles - (scalar string) input disk files to be converted into GEIS
files. Wildcards are allowed.
FILES CREATED:
GEIS files:
The GEIS file is reconstructed from each input Fits file. The
output filename is composed from the rootname of the observation
and the appropriate GEIS file extension (i.e. d0h/d, c0h/d, etc.).
Tables:
If input file is a fits table, the output is an SDAS table.
EXAMPLES:
a) Reconstruct the GEIS file for disk FITS file z29i020ct*.fits.
st_diskread,'z29i020ct*.fits'
PROCEDURES CALLED:
ST_DISK_DATA, ST_DISK_TABLE, ST_DISK_GEIS
FTSIZE,SXPAR(),TAB_CREATE, TAB_WRITE
HISTORY:
10/17/94 JKF/ACC - taken from ST_TAPEREAD.
11/02/94 JKF/ACC - added /block on open statement to
handle files with 512 bytes/record.
12/6/95 JKF/ACC - include new jitter files...replaces
st_read_jitter.pro.
03/5/96 W. Landsman, change FORRD to READU, remove Version 1
type codes, add message facility
05/20/00 W. Landsman, remove obsolete !ERR calls, new calling
sequence to FTINFO
09/2006 W. Landsman, remove obsolete keywords to OPEN
****************************************************************************
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/st_diskread.pro)
ST_DISK_DATA
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NAME:
ST_DISK_DATA
PURPOSE:
Routine to read next header and data array from an HST FITS disk file.
This is a subroutine of ST_DISKREAD and not intended for stand alone
use.
CALLING SEQUENCE:
st_disk_data,unit,h,data,name,gcount,dimen,opsize,nbytes,itype
INPUTS:
unit - logical unit number.
OUTPUTS:
h - FITS header
data - data array
name - file name
gcount - number of groups
dimen - data dimensions
opsize - parameter blocks size
nbytes - bytes per data group
itype - idl data type
Notes:
This is not a standalone program. Use ST_DISKREAD.
PROCEDURES CALLED:
GETTOK(), SXPAR()
HISTORY:
10/17/94 JKF/ACC - taken from ST_TAPE_DATA.
***************************************************************************
(See astrolib/pro/st_diskread.pro)
ST_DISK_GEIS
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NAME:
ST_DISK_GEIS
PURPOSE:
Routine to construct GEIS files from ST FITS disk files.
CALLING SEQUENCE:
ST_DISK_GEIS, h, data, htab, tab, table_available, name, gcount,
dimen,opsize, nbytes_g,itype
INPUT PARAMETERS:
h - header for data
data - data array
htab - header for the table
tab - fits table
table_available - logical variable (1 if table was found)
name - data set name
gcount - number of groups
dimen - data dimensions
opsize - original parameter block size
nbytes_g - number of bytes per group
itype - idl integer data type value for the output data groups
SIDE EFFECTS:
GEIS file updated with group parameters in unit 1 (already open)
and header file created
NOTES:
This is not a standalone program. Use st_diskread.
During the creation of the header, this routine performs the
following steps:
1) create a basic fits header (7 keywords)
2) adjust basic fits header for the number of axis present (i.e. >1)
3) adjust basic fits header for parameter keywords (i.e. ptype,etc)
4) from this point, sequentially copies keywords until it hits one of
the following keywords 'INSTRUME','INSTRUID', or 'CONFG'.
5) append 'END' statement
PROCEDURES CALLED:
FTSIZE, SXADDPAR, SXHWRITE
HISTORY:
10/17/94 JKF/ACC - taken from ST_DISK_GEIS
****************************************************************************
(See astrolib/pro/st_diskread.pro)
ST_DISK_TABLE
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NAME:
ST_DISK_TABLE
PURPOSE:
Routine to read FITS table from an ST fits on disk.
This is a subroutine of st_diskread and not intended for stand alone
use.
CALLING SEQUENCE:
st_disk_table,unit,h,data
INPUTS PARAMETER:
unit - disk unit number
OUTPUTS:
h - FITS header
data - table array
NOTES:
This is not a standalone program. Use ST_DISKREAD.
HISTORY:
10/17/94 JKF/ACC - taken from ST_TAPE_TABLE.
12/7/95 JKF/ACC - handle tables for jitter data.
****************************************************************************
(See astrolib/pro/st_diskread.pro)
SUBSTAR
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NAME:
SUBSTAR
PURPOSE:
Subtract a scaled point spread function at specified star position(s).
EXPLANATION:
Part of the IDL-DAOPHOT photometry sequence
CALLING SEQUENCE:
SUBSTAR, image, x, y, mag, [ id, psfname, /VERBOSE]
INPUT-OUTPUT:
IMAGE - On input, IMAGE is the original image array. A scaled
PSF will be subtracted from IMAGE at specified star positions.
Make a copy of IMAGE before calling SUBSTAR, if you want to
keep a copy of the unsubtracted image array
INPUTS:
X - REAL Vector of X positions found by NSTAR (or FIND)
Y - REAL Vector of Y positions found by NSTAR (or FIND)
MAG - REAL Vector of stellar magnitudes found by NSTAR (or APER)
Used to scale the PSF to match intensity at star position.
Stars with magnitude values of 0.0 are assumed missing and
ignored in the subtraction.
OPTIONAL INPUTS:
ID - Index vector indicating which stars are to be subtracted. If
omitted, (or set equal to -1), then stars will be subtracted
at all positions specified by the X and Y vectors.
PSFNAME - Name of the FITS file containing the PSF residuals, as
generated by GETPSF. SUBSTAR will prompt for this parameter
if not supplied.
OPTIONAL INPUT KEYWORD:
VERBOSE - If this keyword is set and nonzero, then SUBSTAR will
display the star that it is currently processing
COMMON BLOCKS:
The RINTER common block is used (see RINTER.PRO) to save time in the
PSF calculations
PROCEDURES CALLED:
DAO_VALUE(), READFITS(), REMOVE, SXOPEN, SXPAR(), SXREAD()
REVISION HISTORY:
Written, W. Landsman August, 1988
Added VERBOSE keyword January, 1992
Fix star subtraction near edges, W. Landsman May, 1996
Assume the PSF file is in FITS format W. Landsman July, 1997
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/substar.pro)
SUNPOS
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NAME:
SUNPOS
PURPOSE:
To compute the RA and Dec of the Sun at a given date.
CALLING SEQUENCE:
SUNPOS, jd, ra, dec, [elong, obliquity, /RADIAN ]
INPUTS:
jd - The Julian date of the day (and time), scalar or vector
usually double precision
OUTPUTS:
ra - The right ascension of the sun at that date in DEGREES
double precision, same number of elements as jd
dec - The declination of the sun at that date in DEGREES
OPTIONAL OUTPUTS:
elong - Ecliptic longitude of the sun at that date in DEGREES.
obliquity - the obliquity of the ecliptic, in DEGREES
OPTIONAL INPUT KEYWORD:
/RADIAN - If this keyword is set and non-zero, then all output variables
are given in Radians rather than Degrees
NOTES:
Patrick Wallace (Rutherford Appleton Laboratory, UK) has tested the
accuracy of a C adaptation of the sunpos.pro code and found the
following results. From 1900-2100 SUNPOS gave 7.3 arcsec maximum
error, 2.6 arcsec RMS. Over the shorter interval 1950-2050 the figures
were 6.4 arcsec max, 2.2 arcsec RMS.
The returned RA and Dec are in the given date's equinox.
Procedure was extensively revised in May 1996, and the new calling
sequence is incompatible with the old one.
METHOD:
Uses a truncated version of Newcomb's Sun. Adapted from the IDL
routine SUN_POS by CD Pike, which was adapted from a FORTRAN routine
by B. Emerson (RGO).
EXAMPLE:
(1) Find the apparent RA and Dec of the Sun on May 1, 1982
IDL> jdcnv, 1982, 5, 1,0 ,jd ;Find Julian date jd = 2445090.5
IDL> sunpos, jd, ra, dec
IDL> print,adstring(ra,dec,2)
02 31 32.61 +14 54 34.9
The Astronomical Almanac gives 02 31 32.58 +14 54 34.9 so the error
in SUNPOS for this case is < 0.5".
(2) Find the apparent RA and Dec of the Sun for every day in 1997
IDL> jdcnv, 1997,1,1,0, jd ;Julian date on Jan 1, 1997
IDL> sunpos, jd+ dindgen(365), ra, dec ;RA and Dec for each day
MODIFICATION HISTORY:
Written by Michael R. Greason, STX, 28 October 1988.
Accept vector arguments, W. Landsman April,1989
Eliminated negative right ascensions. MRG, Hughes STX, 6 May 1992.
Rewritten using the 1993 Almanac. Keywords added. MRG, HSTX,
10 February 1994.
Major rewrite, improved accuracy, always return values in degrees
W. Landsman May, 1996
Added /RADIAN keyword, W. Landsman August, 1997
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/sunpos.pro)
SUNSYMBOL
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NAME:
SUNSYMBOL
PURPOSE:
Return the Sun symbol as a subscripted postscript character string
EXPLANATION:
Returns the Sun symbol (circle with a dot in the middle) as a
(subscripted) postscript character string. Needed because although
the Sun symbol is available using the vector fonts as the string
'!9n', it is not in the standard postscript set.
CALLING SEQUENCE:
result = SUNSYMBOL([FONT= ])
INPUTS:
None
OPTIONAL INPUT KEYWORDS:
font = scalar font graphics keyword (-1,0 or 1) for text. Note that
this keyword is useful for printing text with XYOUTS but *not*
e.g. the XTIT keyword to PLOT where the font call to PLOT takes
precedence.
OUTPUTS:
result - a scalar string representing the Sun symbol. A different
string is output depending (1) the device is postscript and
hardware fonts are used (!P.FONT=0), (2) vector fonts are used,
or (3) hardware fonts are used on a non-postscript device.
For case (3), SUNSYMBOL simply outputs the 3 character string
'Sun'
EXAMPLE:
To make the X-axis of a plot read M/M_Sun
IDL> plot,indgen(10),xtit = 'M / M' + sunsymbol()
RESTRICTIONS:
(1) The postscript output does not have the dot perfectly centered in
the circle. For a better symbol, consider postprocessing with
psfrag (see http://www.astrobetter.com/idl-psfrag/ ).
(2) SUNSYMBOL() includes subscript output positioning commands in the
output string.
(3) True type fonts (!p.font = 1) are not supported. If you want
to make a Sun symbol with true type fonts, see the discussion of
installing the Marvosym font at http://tinyurl.com/mst5q
REVISION HISTORY:
Written, W. Landsman, HSTX April, 1997
Converted to IDL V5.0 W. Landsman September 1997
Allow font keyword to be passed. T. Robishaw Apr. 2006
(See astrolib/pro/sunsymbol.pro)
SXADDHIST
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NAME:
SXADDHIST
PURPOSE:
Procedure to add HISTORY (or COMMENT) line(s) to a FITS header
EXPLANATION:
The advantage of using SXADDHIST instead of SXADDPAR is that with
SXADDHIST many HISTORY or COMMENT records can be added in a single call.
CALLING SEQUENCE
sxaddhist, history, header, [ /PDU, /COMMENT ]
INPUTS:
history - string or string array containing history or comment line(s)
to add to the FITS header
INPUT/OUTPUT
header - FITS header (string array). Upon output, it will contain the
specified HISTORY records added to the end
OPTIONAL KEYWORD INPUTS:
/BLANK - If specified then blank (' ') keywords will be written
rather than 'HISTORY ' keywords.
/COMMENT - If specified, then 'COMMENT ' keyword will be written rather
than 'HISTORY ' keywords.
Note that according to the FITS definition, any number of
'COMMENT' and 'HISTORY' or blank keywords may appear in a header,
whereas all other keywords may appear only once.
LOCATION=key - If present, the history will be added before this
keyword. Otherwise put it at the end.
/PDU - if specified, the history will be added to the primary
data unit header, (before the line beginning BEGIN EXTENSION...)
Otherwise, it will be added to the end of the header.
This has meaning only for extension headers using the STScI
inheritance convention.
OUTPUTS:
header - updated FITS header
EXAMPLES:
sxaddhist, 'I DID THIS', header ;Add one history record
hist = strarr(3)
hist[0] = 'history line number 1'
hist[1[ = 'the next history line'
hist[2] = 'the last history line'
sxaddhist, hist, header ;Add three history records
SIDE EFFECTS:
Header array is truncated to the final END statement
LOCATION overrides PDU.
HISTORY:
D. Lindler Feb. 87
April 90 Converted to new idl D. Lindler
Put only a single space after HISTORY W. Landsman November 1992
Aug. 95 Added PDU keyword parameters
LOCATION added. M. Greason, 28 September 2004.
Missing minus sign (1 -> -1) in testing for WHERE output when
looking for location to insert a comment M. Haffner Oct 2012
(See astrolib/pro/sxaddhist.pro)
SXADDPAR
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NAME:
SXADDPAR
PURPOSE:
Add or modify a parameter in a FITS header array.
CALLING SEQUENCE:
SXADDPAR, Header, Name, Value, [ Comment, Location, /SaveComment,
BEFORE =, AFTER = , FORMAT= , /PDU]
INPUTS:
Header = String array containing FITS or STSDAS header. The
length of each element must be 80 characters. If not
defined, then SXADDPAR will create an empty FITS header array.
Name = Name of parameter. If Name is already in the header the value
and possibly comment fields are modified. Otherwise a new
record is added to the header. If name is equal to 'COMMENT'
or 'HISTORY' or a blank string then the value will be added to
the record without replacement. For these cases, the comment
parameter is ignored.
Value = Value for parameter. The value expression must be of the
correct type, e.g. integer, floating or string. String values
of 'T' or 'F' are considered logical values.
OPTIONAL INPUT PARAMETERS:
Comment = String field. The '/' is added by this routine. Added
starting in position 31. If not supplied, or set equal to
'', or /SAVECOMMENT is set, then the previous comment field is
retained (when found)
Location = Keyword string name. The parameter will be placed before the
location of this keyword. This parameter is identical to
the BEFORE keyword and is kept only for consistency with
earlier versions of SXADDPAR.
OPTIONAL INPUT KEYWORD PARAMETERS:
BEFORE = Keyword string name. The parameter will be placed before the
location of this keyword. For example, if BEFORE='HISTORY'
then the parameter will be placed before the first history
location. This applies only when adding a new keyword;
keywords already in the header are kept in the same position.
AFTER = Same as BEFORE, but the parameter will be placed after the
location of this keyword. This keyword takes precedence over
BEFORE.
FORMAT = Specifies FORTRAN-like format for parameter, e.g. "F7.3". A
scalar string should be used. For complex numbers the format
should be defined so that it can be applied separately to the
real and imaginary parts. If not supplied then the default is
'G19.12' for double precision, and 'G14.7' for floating point.
/PDU = specifies keyword is to be added to the primary data unit
header. If it already exists, it's current value is updated in
the current position and it is not moved.
/SAVECOMMENT = if set, then any existing comment is retained, i.e. the
COMMENT parameter only has effect if the keyword did not
previously exist in the header.
OUTPUTS:
Header = updated FITS header array.
EXAMPLE:
Add a keyword 'TELESCOP' with the value 'KPNO-4m' and comment 'Name
of Telescope' to an existing FITS header h.
IDL> sxaddpar, h, 'TELESCOPE','KPNO-4m','Name of Telescope'
NOTES:
The functions SXADDPAR() and FXADDPAR() are nearly identical, with the
major difference being that FXADDPAR forces required FITS keywords
BITPIX, NAXISi, EXTEND, PCOUNT, GCOUNT to appear in the required order
in the header, and FXADDPAR supports the OGIP LongString convention.
There is no particular reason for having two nearly identical
procedures, but both are too widely used to drop either one.
All HISTORY records are inserted in order at the end of the header.
All COMMENT records are also inserted in order at the end of the header
header, but before the HISTORY records. The BEFORE and AFTER keywords
can override this.
All records with no keyword (blank) are inserted in order at the end of
the header, but before the COMMENT and HISTORY records. The BEFORE and
AFTER keywords can override this.
RESTRICTIONS:
Warning -- Parameters and names are not checked
against valid FITS parameter names, values and types.
MODIFICATION HISTORY:
DMS, RSI, July, 1983.
D. Lindler Oct. 86 Added longer string value capability
Converted to NEWIDL D. Lindler April 90
Added Format keyword, J. Isensee, July, 1990
Added keywords BEFORE and AFTER. K. Venkatakrishna, May '92
Pad string values to at least 8 characters W. Landsman April 94
Aug 95: added /PDU option and changed routine to update last occurence
of an existing keyword (the one SXPAR reads) instead of the
first occurence.
Comment for string data can start after column 32 W. Landsman June 97
Make sure closing quote supplied with string value W. Landsman June 98
Converted to IDL V5.0 W. Landsman June 98
Increase precision of default formatting of double precision floating
point values. C. Gehman, JPL September 1998
Mar 2000, D. Lindler, Modified to use capital E instead of lower case
e for exponential formats.
Apr 2000, Make user-supplied format upper-case W. Landsman
Oct 2001, Treat COMMENT or blank string like HISTORY keyword W. Landsman
Jan 2002, Allow BEFORE, AFTER to apply to COMMENT keywords W. Landsman
June 2003, Added SAVECOMMENT keyword W. Landsman
Jan 2004, If END is missing, then add it at the end W. Landsman
May 2005 Fix SAVECOMMENT error with non-string values W. Landsman
Oct 2005 Jan 2004 change made SXADDPAR fail for empty strings W.L.
May 2011 Fix problem with slashes in string values W.L.
(See astrolib/pro/sxaddpar.pro)
SXDELPAR
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NAME:
SXDELPAR
PURPOSE:
Procedure to delete a keyword parameter(s) from a FITS header
CALLING SEQUENCE:
sxdelpar, h, parname
INPUTS:
h - FITS or STSDAS header, string array
parname - string or string array of keyword name(s) to delete
OUTPUTS:
h - updated FITS header, If all lines are deleted from
the header, then h is returned with a value of 0
EXAMPLE:
Delete the astrometry keywords CDn_n from a FITS header, h
IDL> sxdelpar, h, ['CD1_1','CD1_2','CD2_1','CD2_2']
NOTES:
(1) No message is returned if the keyword to be deleted is not found
(2) All appearances of a keyword in the header will be deleted
HISTORY:
version 1 D. Lindler Feb. 1987
Test for case where all keywords are deleted W. Landsman Aug 1995
Allow for headers with more than 32767 lines W. Landsman Jan. 2003
Use ARRAY_EQUAL, cleaner syntax W. L. July 2009
(See astrolib/pro/sxdelpar.pro)
SXGINFO
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NAME:
SXGINFO
PURPOSE:
Return information on all group parameters in an STSDAS header.
EXPLANATION:
Return datatype, starting byte, and number bytes for all group
parameters in an STSDAS file. Obtaining these values
greatly speed up execution time in subsequent calls to SXGPAR.
CALLING SEQUENCE:
sxginfo, h, par, type, sbyte, nbytes
INPUTS:
h - header returned by SXOPEN
par - parameter block returned by SXREAD or multiple
parameter blocks stored in array of dimension
greater than one.
OUTPUT:
type - data type (if not supplied or null string, the
header is searched for type,sbyte, and nbytes)
sbyte - starting byte in parameter block for data
nbytes - number of bytes in parameter block for data
The number of elements in type,sbyte and nbytes equals the total
number of group parameters.
METHOD:
The parameter type for each parameter is obtained
from PDTYPEn keyword. If not found then DATATYPE keyword
value is used. If that is not found then BITPIX is
used. BITPIX=8, byte; BITPIX=16 integer*2; BITPIX=32
integer*4.
NOTES:
For an example of the use of SXGINFO, see CONV_STSDAS
HISTORY:
version 1 W. Landsman Apr. 93
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/sxginfo.pro)
SXGPAR
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NAME:
SXGPAR
PURPOSE:
Obtain group parameter value in SDAS/FITS file
CALLING SEQUENCE:
result = sxgpar( h, par, name, [ type, sbyte, nbytes] )
INPUTS:
h - header returned by SXOPEN
par - parameter block returned by SXREAD or multiple
parameter blocks stored in array of dimension
greater than one.
name - parameter name (keyword PTYPEn) or integer
parameter number.
OPTIONAL INPUT/OUTPUT
type - data type (if not supplied or null string, the
header is searched for type,sbyte, and nbytes)
sbyte - starting byte in parameter block for data
nbytes - number of bytes in parameter block for data
OUTPUT:
parameter value or value(s) returned as function value
SIDE EFFECTS:
If an error occured then !err is set to -1
OPERATIONAL NOTES:
Supplying type, sbyte and nbytes greatly decreases execution
time. The best way to get the types is on the first call
pass undefined variables for the three parameters or set
type = ''. The routine will then return their values for
use in subsequent calls.
METHOD:
The parameter type for parameter n is obtained
from PDTYPEn keyword. If not found then DATATYPE keyword
value is used. If that is not found then BITPIX is
used. BITPIX=8, byte; BITPIX=16 integer*2; BITPIX=32
integer*4.
HISTORY:
version 1 D. Lindler Oct. 86
version 2 D. Lindler Jan. 90 added ability to process
multiple parameter blocks in single call
version 3 D. Lindler (converted to New vaxidl)
Apr 14 1991 JKF/ACC - fixed make_array datatypes(float/double)
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/sxgpar.pro)
SXGREAD
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NAME:
SXGREAD
PURPOSE:
Read group parameters from a Space Telescope STSDAS image file
CALLING SEQUENCE:
grouppar = sxgread( unit, group )
INPUTS:
UNIT = Supply same unit as used in SXOPEN.
GROUP = group number to read. if omitted, read first group.
The first group is number 0.
OUTPUTS:
GROUPPAR = parameter values from fits group parameter block.
It is a byte array which may contain multiple data types.
The function SXGPAR can be used to retrieve values from it.
COMMON BLOCKS:
Uses IDL Common STCOMMN to access parameters.
SIDE EFFECTS:
IO is performed.
MODIFICATION HISTORY:
WRITTEN, Don Lindler, July, 1 1987
MODIFIED, Don Neill, Jan 11, 1991 - derived from sxread.pro
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/sxgread.pro)
SXHCOPY
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NAME:
SXHCOPY
PURPOSE:
Copies selected portions of one header to another
CALLING SEQUENCE:
sxhcopy, h, keyword1, keyword2, hout
INPUTS:
h - input header
keyword1 - first keyword to copy
keyword2 - last keyword to copy
INPUT/OUTPUT:
hout - header to copy the information to.
METHOD:
the headers lines from keyword1 to keyword2 are copied to
the end of the output header. No check is made to verify
that a keyword value already exists in the output header.
HISTORY:
version 1 D. Lindler Sept. 1989
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/sxhcopy.pro)
SXHMAKE
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NAME:
SXHMAKE
PURPOSE:
Create a basic STSDAS header file from an IDL data array
CALLING SEQUENCE:
sxhmake, Data, Groups, Header
INPUTS:
Data = IDL data array of the same type, dimensions and
size as are to be written to file.
Groups = # of groups to be written.
OUTPUTS:
Header = String array containing ST header file.
PROCEDURE:
Call sxhmake to create a header file. Then call sxopen to
open output image, followed by sxwrite to write the data.
If you do not plan to change the header created by sxhmake
before calling sxopen, you might consider using sxmake which
does both steps.
MODIFICATION HISTORY:
Don Lindler Feb 1990 modified from SXMAKE by DMS, July, 1983.
D. Lindler April 90 Converted to new VMS IDL
M. Greason May 1990 Header creation bugs eliminated.
W. Landsman Aug 1997 Use SYSTIME() instead of !STIME for V5.0
Converted to IDL V5.0 W. Landsman September 1997
Recognize unsigned datatype January 2000 W. Landsman
(See astrolib/pro/sxhmake.pro)
SXHREAD
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NAME:
SXHREAD
PURPOSE:
Procedure to read a STSDAS header from disk.
EXPLANATION:
This version of SXHREAD can read two types of disk files
(1) Unix stream files with a CR after every 80 bytes
(2) Variable length record files
(3) Fixed length (80 byte) record files
CALLING SEQUENCE:
sxhread, name, header
INPUT:
name - file name, scalar string. An extension of .hhh is appended
if not already supplied. (Note STSDAS headers are required
to have a 3 letter extension ending in 'h'.) gzip extensions
.gz will be recognized as compressed.
OUTPUT:
header - STSDAS header, string array
NOTES:
SXHREAD does not do any checking to see if the file is a valid
STSDAS header. It simply reads the file into a string array with
80 byte elements
HISTORY:
Version 1 D. Lindler July, 1987
Version 2 M. Greason, August 1990
Use READU for certain ST VAX GEIS files W. Landsman January, 1992
Read variable length Unix files E. Deutsch/W. Landsman November, 1994
Converted to IDL V5.0 W. Landsman September 1997
Updated by E. Artigau to handle gzipped fits August 2004
Remove VMS support, W. Lnadsman September 2006
(See astrolib/pro/sxhread.pro)
SXHWRITE
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NAME:
SXHWRITE
PURPOSE:
Procedure to write an STSDAS or FITS header to disk as a *.hhh file.
CALLING SEQUENCE:
SXHWRITE,name,h
INPUTS:
name - file name. If an extension is supplied it must be 3 characters
ending in "h".
h - FITS header, string array
SIDE EFFECTS:
File with specified name is written. If qualifier not specified
then .hhh is used
SXHWRITE will modify the header in the following ways, if necessary
(1) If not already present, an END statement is added as the
last line. Lines after an existing END statment are
deleted.
(2) Spaces are appended to force each line to be 80 characters.
(3) On Unix machines, a carriage return is appended at the end
of each line. This is consistent with STSDAS and allows
the file to be directly displayed on a stream device
PROCEDURES USED:
zparcheck, fdecomp
HISTORY:
version 1 D. Lindler June 1987
conversion cleaned up. M. Greason, June 1990
Add carriage return at the end of Unix files W. Landsman Oct 1991
Use SYSTIME() instead of !STIME for V5.0 compatibility Aug 1997
Assume since V55, remove VMS support
(See astrolib/pro/sxhwrite.pro)
SXMAKE
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NAME:
SXMAKE
PURPOSE:
Create a basic ST header file from an IDL array prior to writing data.
CALLING SEQUENCE:
sxmake, Unit, File, Data, Par, Groups, Header, [ PSIZE = ]
INPUTS:
Unit = Logical unit number from 1 to 9.
File = file name of data and header files to create. If no file name
extension is supplied then the default is to use .hhh for the
header file extension and .hhd for the data file extension
If an extension is supplied, it should be of the form .xxh
where xx are any alphanumeric characters.
Data = IDL data array of the same type, dimensions and
size as are to be written to file.
Par = # of elements in each parameter block for each data record. If
set equal to 0, then parameter blocks will not be written. The
data type of the parameter blocks must be the same as the data
array. To get around this restriction, use the PSIZE keyword.
Groups = # of groups to write. If 0 then write in basic
format without groups.
OPTIONAL INPUT PARAMETERS:
Header = String array containing ST header file. If this
parameter is omitted, a basic header is constructed.
If included, the basic parameters are added to the
header using sxaddpar. The END keyword must terminate
the parameters in Header.
OPTIONAL KEYWORD INPUT PARAMETER:
PSIZE - Integer scalar giving the number of bits in the parameter
block. If the PSIZE keyword is given, then the Par input
parameter is ignored.
OPTIONAL OUTPUT PARAMETERS:
Header = ST header array, an 80 by N character array.
COMMON BLOCKS:
Stcommn - as used in sxwrite, sxopen, etc.
SIDE EFFECTS:
The header file is created and written and then the
data file is opened on the designated unit.
RESTRICTIONS:
Header files must be named .xxh and data files must be
named .xxd, where xx are any alphanumeric characters.
PROCEDURE:
Call sxmake to create a header file. Then call sxwrite
to output each group.
PROCEDURES USED:
GET_DATE, SXADDPAR, SXOPEN
MODIFICATION HISTORY:
DMS, July, 1983.
converted to new VMS IDL April 90
Use SYSTIME() instead of !STIME W. Landsman Aug 1997
Converted to IDL V5.0 W. Landsman September 1997
Added optional PSIZE keyword August 1999 W. Landsman
Recognize unsigned datatype January 2000 W. Landsman
(See astrolib/pro/sxmake.pro)
SXOPEN
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NAME:
SXOPEN
PURPOSE:
Open a Space Telescope formatted (STSDAS) header file.
EXPLANATION:
Saves the parameters required subsequent SX routines in
the common block Stcommn. Optionally save the header in
the string array Header, and the history in the string array
History. Open the data file associated with this
header on the same unit.
CALLING SEQUENCE:
SXOPEN, Unit, Fname [, Header [,History] [,Access]]
INPUTS:
Unit = IDL unit used for IO. Must be from 1 to 9.
Fname = File name of header file. Default extension
is .hhh for header files and .hhd for data
files. If an extension is supplied it must have the
form .xxh where xx are any alphanumeric characters. The
data file must have extension .xxd
No version number is allowed. Most recent versions
of the files are used.
OPTIONAL INPUT PARAMETER:
Access = 'R' to open for read, 'W' to open for write.
OUTPUTS:
Stcommn = Common block containing ST parameter blocks.
(Long arrays.)
OPTIONAL OUTPUT PARAMETERS:
Header = 80 char by N string array containing the
names, values and comments from the FITS header.
Use the function SXPAR to obtain individual
parameter values.
History = String array containing the value of the
history parameter.
COMMON BLOCKS:
STCOMMN - Contains RESULT(20,10) where RESULT(i,LUN) =
0 - 121147 for consistency check, 1 - Unit for consistency,
2 - bitpix, 3 - naxis, 4 - groups (0 or 1), 5 - pcount,
6 - gcount, 7 - psize, 8 - data type as idl type code,
9 - bytes / record, 10 to 10+N-1 - dimension N,
17 = record length of file in bytes.
18 - # of groups written, 19 = gcount.
SIDE EFFECTS:
The data and header files are accessed.
RESTRICTIONS:
Works only for disc files. The data file must have
must have the extension ".xxd" and the header file must
have the extension ".xxh" where x is any alphanumeric character
PROCEDURE:
The header file is opened and each line is read.
Important parameters are stored in the output
parameter. If the last two parameters are specified
the parameter names and values are stored. The common
block STCOMMN is filled with the type of data, dimensions,
etc. for use by SXREAD.
If access is for write, each element of the header
array, which must be supplied, is written to the
header file. The common block is filled with
relevant parameters for SXWRITE. A keyword of "END"
ends the header.
MODIFICATION HISTORY:
Written, DMS, May, 1983.
D. Lindler Feb. 1990
Modified to allow var. record length header files.
D. Lindler April 1990 Conversion to new VMS IDL
Added /BLOCK when opening new .hhd file
Converted to IDL V5.0 W. Landsman September 1997
Recognize unsigned datatype for V5.1 or greater W. Landsman Jan 2000
Assume since V5.5 W. Landsman Sep 2006
(See astrolib/pro/sxopen.pro)
SXPAR
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NAME:
SXPAR
PURPOSE:
Obtain the value of a parameter in a FITS header
CALLING SEQUENCE:
result = SXPAR( Hdr, Name, [ Abort, COUNT=, COMMENT =, /NoCONTINUE,
/SILENT ])
INPUTS:
Hdr = FITS header array, (e.g. as returned by READFITS)
string array, each element should have a length of 80 characters
Name = String name of the parameter to return. If Name is of the
form 'keyword*' then an array is returned containing values of
keywordN where N is a positive (non-zero) integer. The value of
keywordN will be placed in RESULT[N-1]. The data type of RESULT
will be the type of the first valid match of keywordN found.
OPTIONAL INPUTS:
ABORT - string specifying that SXPAR should do a RETALL
if a parameter is not found. ABORT should contain
a string to be printed if the keyword parameter is not found.
If not supplied, SXPAR will return quietly with COUNT = 0
(and !ERR = -1) if a keyword is not found.
OPTIONAL INPUT KEYWORDS:
/NOCONTINUE = If set, then continuation lines will not be read, even
if present in the header
/SILENT - Set this keyword to suppress warning messages about duplicate
keywords in the FITS header.
OPTIONAL OUTPUT KEYWORDS:
COUNT - Optional keyword to return a value equal to the number of
parameters found by SXPAR, integer scalar
COMMENT - Array of comments associated with the returned values
OUTPUTS:
Function value = value of parameter in header.
If parameter is double precision, floating, long or string,
the result is of that type. Apostrophes are stripped
from strings. If the parameter is logical, 1b is
returned for T, and 0b is returned for F.
If Name was of form 'keyword*' then a vector of values
are returned.
SIDE EFFECTS:
!ERR is set to -1 if parameter not found, 0 for a scalar
value returned. If a vector is returned it is set to the
number of keyword matches found. The use of !ERR is deprecated, and
instead the COUNT keyword is preferred
If a keyword (except HISTORY or COMMENT) occurs more than once in a
header, a warning is given, and the *last* occurence is used.
EXAMPLES:
Given a FITS header, h, return the values of all the NAXISi values
into a vector. Then place the history records into a string vector.
IDL> naxisi = sxpar( h ,'NAXIS*') ; Extract NAXISi value
IDL> history = sxpar( h, 'HISTORY' ) ; Extract HISTORY records
PROCEDURE:
The first 8 chacters of each element of Hdr are searched for a
match to Name. The value from the last 20 characters is returned.
An error occurs if there is no parameter with the given name.
If a numeric value has no decimal point it is returned as type
LONG. If it contains more than 8 numerals, or contains the
characters 'D' or 'E', then it is returned as type DOUBLE. Otherwise
it is returned as type FLOAT. Very large integer values, outside
the range of valid LONG, are returned as DOUBLE.
If the value is too long for one line, it may be continued on to the
the next input card, using the OGIP CONTINUE convention. For more info,
see http://fits.gsfc.nasa.gov/registry/continue_keyword.html
Complex numbers are recognized as two numbers separated by one or more
space characters.
If a numeric value has no decimal point (or E or D) it is returned as
type LONG. If it contains more than 8 numerals, or contains the
character 'D', then it is returned as type DOUBLE. Otherwise it is
returned as type FLOAT. If an integer is too large to be stored as
type LONG, then it is returned as DOUBLE.
NOTES:
The functions SXPAR() and FXPAR() are nearly identical, although
FXPAR() has slightly more sophisticated parsing, and additional keywords
to specify positions in the header to search (for speed), and to force
the output to a specified data type.. There is no
particular reason for having two nearly identical procedures, but
both are too widely used to drop either one.
PROCEDURES CALLED:
GETTOK(), VALID_NUM()
MODIFICATION HISTORY:
DMS, May, 1983, STPAR Written.
D. Lindler Jan 90 added ABORT input parameter
J. Isensee Jul,90 added COUNT keyword
W. Thompson, Feb. 1992, added support for FITS complex values.
W. Thompson, May 1992, corrected problem with HISTORY/COMMENT/blank
keywords, and complex value error correction.
W. Landsman, November 1994, fix case where NAME is an empty string
W. Landsman, March 1995, Added COMMENT keyword, ability to read
values longer than 20 character
W. Landsman, July 1995, Removed /NOZERO from MAKE_ARRAY call
T. Beck May 1998, Return logical as type BYTE
W. Landsman May 1998, Make sure integer values are within range of LONG
W. Landsman Feb 1998, Recognize CONTINUE convention
W. Landsman Oct 1999, Recognize numbers such as 1E-10 as floating point
W. Landsman Jan 2000, Only accept integer N values when name = keywordN
W. Landsman Dec 2001, Optional /SILENT keyword to suppress warnings
W. Landsman/D. Finkbeiner Mar 2002 Make sure extracted vectors
of mixed data type are returned with the highest type.
W.Landsman Aug 2008 Use vector form of VALID_NUM()
W. Landsman Jul 2009 Eliminate internal recursive call
W. Landsman Apr 2012 Require vector numbers be greater than 0
(See astrolib/pro/sxpar.pro)
SXREAD
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NAME:
SXREAD
PURPOSE:
Read a Space Telescope STSDAS image file
CALLING SEQUENCE:
result = sxread( Unit, group , [par] )
INPUTS:
UNIT = Unit number of file, must be from 1 to 9.
Unit must have been opened with SXOPEN.
GROUP = group number to read. if omitted, read first record.
The first record is number 0.
OUTPUTS:
Result of function = array constructed from designated record.
OPTIONAL OUTPUT:
PAR = Variable name into which parameter values from STSDAS
group parameter block are read. It is a byte array
which may contain multiple data types. The function
SXGPAR can be used to retrieve values from it.
COMMON BLOCKS:
Uses IDL Common STCOMMN to access parameters.
NOTES:
Use the function SXGREAD to read the group parameter blocks without
having to read the group array.
If the STSDAS file does not contain groups, then the optional output
parameter PAR is returned undefined, but no error message is given.
SIDE EFFECTS:
IO is performed.
MODIFICATION HISTORY:
WRITTEN, Don Lindler, July, 1 1987
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/sxread.pro)
SXWRITE
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NAME:
SXWRITE
PURPOSE:
Write a group of data and parameters in ST format
to a STSDAS data file.
CALLING SEQUENCE:
SXWRITE, Unit, Data,[ Par]
INPUTS:
Unit = unit number of file. The file must have been
previously opened by SXOPEN.
Data = Array of data to be written. The dimensions
must agree with those supplied to SXOPEN and written
into the FITS header. The type is converted if
necessary.
OPTIONAL INPUT PARAMETERS:
Par = parameter block. The size of this array must
agree with the Psize parameter in the FITS header.
OUTPUTS:
None.
COMMON BLOCKS:
STCOMMN - Contains RESULT(20,10) where RESULT(i,LUN) =
0 - 121147 for consistency check, 1 - Unit for consistency,
2 - bitpix, 3 - naxis, 4 - groups (0 or 1), 5 - pcount,
6 - gcount, 7 - psize, 8 - data type as idl type code,
9 - bytes / record, 10 to 10+N-1 - dimension N,
18 - # of groups written, 19 = gcount.
SIDE EFFECTS:
The data are written into the next group.
RESTRICTIONS:
SXOPEN must have been called to initialize the
header and the common block.
MODIFICATION HISTORY:
DMS, July, 1983.
D.Lindler July, 1986 - changed block size of file to 512
moved group parameters after the groups data.
D.Lindler July, 1987 - modified to allow any size parameter block
(in bytes).
D. Lindler April, 1990 - converted to new VMS IDL
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/sxwrite.pro)
TABINV
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NAME:
TABINV
PURPOSE:
To find the effective index of a function value in an ordered vector.
CALLING SEQUENCE:
TABINV, XARR, X, IEFF, [/FAST]
INPUTS:
XARR - the vector array to be searched, must be monotonic
increasing or decreasing
X - the function value(s) whose effective
index is sought (scalar or vector)
OUTPUT:
IEFF - the effective index or indices of X in XARR
always floating point, same # of elements as X
OPTIONAL KEYWORD INPUT:
/FAST - If this keyword is set, then the input vector is not checked
for monotonicity, in order to improve the program speed.
RESTRICTIONS:
TABINV will abort if XARR is not monotonic. (Equality of
neighboring values in XARR is allowed but results may not be
unique.) This requirement may mean that input vectors with padded
zeroes could cause routine to abort.
PROCEDURE:
VALUE_LOCATE() is used to find the values XARR[I]
and XARR[I+1] where XARR[I] < X < XARR[I+1].
IEFF is then computed using linear interpolation
between I and I+1.
IEFF = I + (X-XARR[I]) / (XARR[I+1]-XARR[I])
Let N = number of elements in XARR
if x < XARR[0] then IEFF is set to 0
if x > XARR[N-1] then IEFF is set to N-1
EXAMPLE:
Set all flux values of a spectrum (WAVE vs FLUX) to zero
for wavelengths less than 1150 Angstroms.
IDL> tabinv, wave, 1150.0, I
IDL> flux[ 0:fix(I) ] = 0.
FUNCTIONS CALLED:
None
REVISION HISTORY:
Adapted from the IUE RDAF January, 1988
More elegant code W. Landsman August, 1989
Mod to work on 2 element decreasing vector August, 1992
Updated for V5.3 to use VALUE_LOCATE() W. Landsman January 2000
Work when both X and Xarr are integers W. Landsman August 2001
Use ARRAY_EQUAL, always internal double precision W.L. July 2009
Allow Double precision output, faster test for monotonicity.
WL, January 2012
(See astrolib/pro/tabinv.pro)
TAG_EXIST()
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NAME:
TAG_EXIST()
PURPOSE:
To test whether a tag name exists in a structure.
EXPLANATION:
Routine obtains a list of tagnames and tests whether the requested one
exists or not. The search is recursive so if any tag names in the
structure are themselves structures the search drops down to that level.
(However, see the keyword TOP_LEVEL).
CALLING SEQUENCE:
status = TAG_EXIST(str, tag, [ INDEX =, /TOP_LEVEL, /QUIET ] )
INPUT PARAMETERS:
str - structure variable to search
tag - tag name to search for, scalar string
OUTPUTS:
Function returns 1b if tag name exists or 0b if it does not.
OPTIONAL INPUT KEYWORD:
/TOP_LEVEL = If set, then only the top level of the structure is
searched.
/QUIET - if set, then do not print messages if invalid parameters given
/RECURSE - does nothing but kept for compatibility with the
Solarsoft version for which recursion is not the default
http://sohowww.nascom.nasa.gov/solarsoft/gen/idl/struct/tag_exist.pro
OPTIONAL OUTPUT KEYWORD:
INDEX = index of matching tag, scalar longward, -1 if tag name does
not exist
EXAMPLE:
Determine if the tag 'THICK' is in the !P system variable
IDL> print,tag_exist(!P,'THICK')
PROCEDURE CALLS:
None.
MODIFICATION HISTORY: :
Written, C D Pike, RAL, 18-May-94
Passed out index of matching tag, D Zarro, ARC/GSFC, 27-Jan-95
William Thompson, GSFC, 6 March 1996 Added keyword TOP_LEVEL
Zarro, GSFC, 1 August 1996 Added call to help
Use SIZE(/TNAME) rather than DATATYPE() W. Landsman October 2001
Added /RECURSE and /QUIET for compatibility with Solarsoft version
W. Landsman March 2009
Slightly faster algorithm W. Landsman July 2009
July 2009 update was not setting Index keyword W. L Sep 2009.
Use V6.0 notation W.L. Jan 2012
Not setting index again, sigh W.L./ K. Allers Jan 2012
(See astrolib/pro/tag_exist.pro)
TBDELCOL
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NAME:
TBDELCOL
PURPOSE:
Delete a column of data from a FITS binary table
CALLING SEQUENCE:
TBDELCOL, h, tab, name
INPUTS-OUPUTS
h,tab - FITS binary table header and data array. H and TAB will
be updated with the specified column deleted
INPUTS:
name - Either (1) a string giving the name of the column to delete
or (2) a scalar giving the column number to delete
EXAMPLE:
Delete the column "FLUX" from FITS binary table test.fits
IDL> tab = readfits('test.fits',h,/ext) ;Read table
IDL> tbdelcol, h, tab, 'FLUX' ;Delete Flux column
IDL> modfits,'test.fits',tab,h,/ext ;Write back table
PROCEDURES USED:
SXADDPAR, TBINFO, TBSIZE
REVISION HISTORY:
Written W. Landsman STX Co. August, 1988
Use new structure returned by TBINFO, August, 1997
Use SIZE(/TNAME) instead of DATATYPE() October 2001
Use /NOSCALE in call to TBINFO, update TDISP W. Landsman March 2007
(See astrolib/pro/tbdelcol.pro)
TBDELROW
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NAME:
TBDELROW
PURPOSE:
Delete specified row or rows of data from a FITS binary table
CALLING SEQUENCE:
TBDELROW, h, tab, rows
INPUTS-OUPUTS
h,tab - FITS binary table header and data array. H and TAB will
be updated on output with the specified row(s) deleted.
rows - scalar or vector, specifying the row numbers to delete
First row has index 0. If a vector it will be sorted and
duplicates removed by TBDELROW
EXAMPLE:
Compress a table to include only non-negative flux values
flux = TBGET(h,tab,'FLUX') ;Obtain original flux vector
bad = where(flux lt 0) ;Find negative fluxes
TBDELROW,h,tab,bad ;Delete rows with negative fluxes
PROCEDURE:
Specified rows are deleted from the data array, TAB. The NAXIS2
keyword in the header is updated.
REVISION HISTORY:
Written W. Landsman STX Co. August, 1988
Checked for IDL Version 2, J. Isensee, July, 1990
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/tbdelrow.pro)
TBGET
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NAME:
TBGET
PURPOSE:
Return value(s) from specified column in a FITS binary table
CALLING SEQUENCE
values = TBGET( h, tab, field, [ rows, nulls, /NOSCALE] )
or
values = TBGET( tb_str, tab, field, [ rows, nulls, /NOSCALE] )
INPUTS:
h - FITS binary table header, e.g. as returned by FITS_READ
or
tb_str - IDL structure extracted from FITS header by TBINFO.
Use of the IDL structure will improve processing speed
tab - FITS binary table array, e.g. as returned by FITS_READ
field - field name or number, scalar
OPTIONAL INPUTS:
rows - scalar or vector giving row number(s)
Row numbers start at 0. If not supplied or set to
-1 then values for all rows are returned
OPTIONAL KEYWORD INPUT:
/NOSCALE - If this keyword is set and nonzero, then the TSCALn and
TZEROn keywords will *not* be used to scale to physical values
Default is to perform scaling
CONTINUE - This keyword does nothing, it is kept for consistency with
with earlier versions of TBGET().
OUTPUTS:
the values for the row are returned as the function value.
Null values are set to 0 or blanks for strings.
OPTIONAL OUTPUT:
nulls - null value flag of same length as the returned data.
Only used for integer data types, B, I, and J
It is set to 1 at null value positions and 0 elsewhere.
If supplied then the optional input, rows, must also
be supplied.
EXAMPLE:
Read the columns labeled 'WAVELENGTH' and 'FLUX' from the second
extension of a FITS file 'spectra.fits' into IDL vectors w and f
IDL> fits_read,'spectra.fits',tab,htab,exten=2 ;Read 2nd extension
IDL> w = tbget(htab,tab,'wavelength')
IDL> f = tbget(htab,tab,'flux')
NOTES:
(1) If the column is variable length ('P') format, then TBGET() will
return the longword array of pointers into the heap area. TBGET()
currently lacks the ability to actually extract the data from the
heap area.
(2) Use the higher-level procedure FTAB_EXT (which calls TBGET()) to
extract vectors directly from the FITS file.
(3) Use the procedure FITS_HELP to determine which extensions are
binary tables, and FTAB_HELP or TBHELP to determine the columns of the
table
PROCEDURE CALLS:
TBINFO, TBSIZE
HISTORY:
Written W. Landsman February, 1991
Work for string and complex W. Landsman April, 1993
Default scaling by TSCALn, TZEROn, Added /NOSCALE keyword,
Fixed nulls output, return longword pointers for variable length
binary tables, W. Landsman December 1996
Added a check for zero width column W. Landsman April, 1997
Add TEMPORARY() and REFORM() for speed W. Landsman May, 1997
Use new structure returned by TBINFO W. Landsman August 1997
Add IS_IEEE_BIG(), No subscripting when all rows requested
W. Landsman March 2000
Use SIZE(/TNAME) instead of DATATYPE() W. Landsman October 2001
Bypass IEEE_TO_HOST call for improved speed W. Landsman November 2002
Cosmetic changes to SIZE() calls W. Landsman December 2002
Added unofficial support for 64bit integers W. Landsman February 2003
Support unsigned integers, new pointer types of TSCAL and TZERO
returned by TBINFO W. Landsman April 2003
Add an i = i[0] for V6.0 compatibility W. Landsman August 2003
Use faster BYTEORDER byteswapping W. Landsman April 2006
Free pointers if FITS header supplied W. Landsman March 2007
(See astrolib/pro/tbget.pro)
TBHELP
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NAME:
TBHELP
PURPOSE:
Routine to print a description of a FITS binary table header
CALLING SEQUENCE:
TBHELP, h, [TEXTOUT = ]
INPUTS:
h - FITS header for a binary table, string array
OPTIONAL INPUT KEYWORD:
TEXTOUT - scalar number (0-7) or string (file name) controling
output device (see TEXTOPEN). Default is TEXTOUT=1, output
to the user's terminal
METHOD:
FITS Binary Table keywords NAXIS*,EXTNAME,TFIELDS,TTYPE*,TFORM*,TUNIT*,
are read from the header and displayed at the terminal
A FITS header is recognized as bein for a binary table if the keyword
XTENSION has the value 'BINTABLE' or 'A3DTABLE'
NOTES:
Certain fields may be truncated in the display
SYSTEM VARIABLES:
Uses the non-standard system variables !TEXTOUT and !TEXTUNIT. These
are automatically defined by TBHELP if they have not been defined
previously.
PROCEDURES USED:
REMCHAR, SXPAR(), TEXTCLOSE, TEXTOPEN, ZPARCHECK
HISTORY:
W. Landsman February, 1991
Parsing of a FITS binary header made more robust May, 1992
Added TEXTOUT keyword August 1997
Define !TEXTOUT if not already present W. Landsman November 2002
Slightly more compact display W. Landsman August 2005
Fix Aug 2005 error omitting TFORM display W. Landsman Sep 2005
(See astrolib/pro/tbhelp.pro)
TBINFO
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NAME:
TBINFO
PURPOSE:
Return an informational IDL structure from a FITS binary table header.
CALLING SEQUENCE:
tbinfo, h, tb_str, [ERRMSG = ]
INPUTS:
h - FITS binary table header, e.g. as returned by READFITS()
OUTPUTS:
tb_str - IDL structure with extracted info from the FITS binary table
header. Tags include
.tbcol - starting column position in bytes, integer vector
.width - width of the field in bytes, integer vector
.idltype - idltype of field, byte vector
7 - string, 4- real*4, 3-integer*4, 5-real*8
.numval - repeat count, longword vector
.tunit - string unit numbers, string vector
.tnull - integer null value for the field, stored as a string vector
so that an empty string indicates that TNULL is not present
.tform - format for the field, string vector
.ttype - field name, string vector
.maxval- maximum number of elements in a variable length array, long
vector
.tscal - pointer array giving the scale factor for converting to
physical values, default 1.0
.tzero - pointer array giving the additive offset for converting to
physical values, default 0.0
.tdisp - recommended output display format
All of the output vectors will have same number of elements, equal
to the number of columns in the binary table.
The .tscal and .tzero values are stored as pointers so as to preserve
the individual data types (e.g. float or double) which may differ
in different columns. For example, to obtain the value of TSCAL for
the third column use *tab_str.tscal[2]
OPTIONAL INPUT KEYWORD:
/NOSCALE - if set, then the TSCAL* and TZERO* keywords are not extracted
from the FITS header, and the .tscal and .tzero pointers do not
appear in the output structure.
OPTIONAL OUTPUT KEYWORD:
ERRMSG = if present, then error messages are returned in this keyword
rather than displayed using the MESSAGE facility
PROCEDURES USED:
SXPAR()
NOTES:
For variable length ('P' format) column, TBINFO returns values for
reading the 2 element longward array of pointers (numval=2,
idltype = 3, width=4)
HISTORY:
Major rewrite to return a structure W. Landsman August 1997
Added "unofficial" 64 bit integer "K" format W. Landsamn Feb. 2003
Store .tscal and .tzero tags as pointers, so as to preserve
type information W. Landsman April 2003
Treat repeat count for string as specifying string length, not number
of elements, added ERRMSG W. Landsman July 2006
Treat logical as character string 'T' or 'F' W. Landsman October 2006
Added NOSCALE keyword W. Landsman March 2007
(See astrolib/pro/tbinfo.pro)
TBPRINT
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NAME:
TBPRINT
PURPOSE:
Procedure to print specified columns & rows of a FITS binary table
CALLING SEQUENCE:
TBPRINT, h, tab, columns, [ rows, TEXTOUT =, FMT=, NUM_HEADER= ]
or
TBPRINT,tb_str, tab, columns, [ rows, TEXTOUT =, FMT=, NUM_HEADER = ]
INPUTS:
h - FITS header for table, string array
or
tb_str - IDL structure extracted from FITS header by TBINFO, useful
when TBPRINT is called many times with the same header
tab - table array
columns - string giving column names, or vector giving
column numbers (beginning with 1). If string
supplied then column names should be separated by comma's.
If set to '*' then all columns are printed in table format
(1 row per line, binary tables only).
rows - (optional) vector of row numbers to print. If
not supplied or set to scalar, -1, then all rows
are printed.
OUTPUTS:
None
OPTIONAL INPUT KEYWORDS:
FMT = Format string for print display. If not supplied, then any
formats in the TDISP keyword fields of the table will be
used, otherwise IDL default formats.
NUM_HEADER_LINES - Number of lines to display the column headers
default = 1). By setting NUM_HEADER_LINES to an integer larger
than 1, one can avoid truncation of the column header labels.
In addition, setting NUM_HEADER_LINES will display commented
lines indicating a FORMAT for reading the data, and a
suggested call to readfmt.pro.
NVAL_PER_LINE - The maximum number of values displayed from a multivalued
column when printing in table format. Default = 6
TEXTOUT - scalar number (0-7) or string (file name) determining
output device (see TEXTOPEN). Default is TEXTOUT=1, output
to the user's terminal
SYSTEM VARIABLES:
Uses nonstandard system variables !TEXTOUT and !TEXTOPEN
Set !TEXTOUT = 3 to direct output to a disk file. The system
variable is overriden by the value of the keyword TEXTOUT
EXAMPLES:
tab = readfits('test.fits',htab,/ext) ;Read first extension into vars
tbprint,h,tab,'STAR ID,RA,DEC' ;print id,ra,dec for all stars
tbprint,h,tab,[2,3,4],indgen(100) ;print columns 2-4 for
first 100 stars
tbprint,h,tab,text="stars.dat" ;Convert entire FITS table to
;an ASCII file named 'stars.dat'
PROCEDURES USED:
GETTOK(), STRNUMBER(), TEXTOPEN, TEXTCLOSE, TBINFO
RESTRICTIONS:
(1) Program does not check whether output length exceeds output
device capacity (e.g. 80 or 132).
(2) Column heading may be truncated to fit in space defined by
the FORMAT specified for the column. Use NUM_HEADER_LINES
to avoid truncation.
(3) Program does not check for null values
(4) Does not work with variable length columns
(5) Will only the display the first value of fields with multiple values
(unless there is one row each with the same number of mulitple values)
If printing in table format (column='*') then up to 6 values
can be printed per line.
HISTORY:
version 1 D. Lindler Feb. 1987
Accept undefined values of rows,columns W. Landsman August 1997
Use new structure returned by TBINFO W. Landsman August 1997
Made formatting more robust W. Landsman March 2000
Use STRSPLIT to parse string column listing W. Landsman July 2002
Wasn't always printing last row W. Landsman Feb. 2003
Better formatting (space between columns) W. Landsman Oct. 2005
Use case-insensitive match with TTYPE, use STRJOIN W.L. June 2006
Fixed check for multiple values W.L. August 2006
Fixed bad index value in August 2006 fix W.L Aug 15 2006
Free-up pointers after calling TBINFO W.L. Mar 2007
Add table format capability W.L. Mar 2010
Add NUM_HEADER_LINE keyword P. Broos Apr 2010
(See astrolib/pro/tbprint.pro)
TBSIZE
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NAME:
TBSIZE
PURPOSE:
Procedure to return the size of a FITS binary table.
CALLING SEQUENCE:
tbsize, h, tab, ncols, nrows, tfields, ncols_all, nrows_all
INPUTS:
h - FITS table header
tab - FITS table array
OUTPUTS:
ncols - number of characters per row in table
nrows - number of rows in table
tfields - number of fields per row
ncols_all - number of characters/row allocated (size of tab)
nrows_all - number of rows allocated
PROCEDURES USED:
SXPAR()
HISTORY
D. Lindler July, 1987
Converted to IDL V5.0 W. Landsman September 1997
Remove obsolete !ERR call W. Landsman May 2000
(See astrolib/pro/tbsize.pro)
TDB2TDT
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NAME:
TDB2TDT
AUTHOR:
Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
[email protected]
UPDATED VERSIONs can be found on my WEB PAGE:
http://cow.physics.wisc.edu/~craigm/idl/idl.html
PURPOSE:
Relativistic clock corrections due to Earth motion in solar system
MAJOR TOPICS:
Planetary Orbits
CALLING SEQUENCE:
corr = TDB2TDT(JD, TBASE=, DERIV=deriv)
DESCRIPTION:
The function TDB2TDT computes relativistic corrections that must
be applied when performing high precision absolute timing in the
solar system.
According to general relativity, moving clocks, and clocks at
different gravitational potentials, will run at different rates
with respect to each other. A clock placed on the earth will run
at a time-variable rate because of the non-constant influence of
the sun and other planets. Thus, for the most demanding
astrophysical timing applications -- high precision pulsar timing
-- times in the accelerating earth observer's frame must be
corrected to an inertial frame, such as the solar system
barycenter (SSB). This correction is also convenient because the
coordinate time at the SSB is the ephemeris time of the JPL
Planetary Ephemeris.
In general, the difference in the rate of Ti, the time kept by an
arbitrary clock, and the rate of T, the ephemeris time, is given
by the expression (Standish 1998):
dTi/dT = 1 - (Ui + vi^2/2) / c^2
where Ui is the potential of clock i, and vi is the velocity of
clock i. However, when integrated, this expression depends on the
position of an individual clock. A more convenient approximate
expression is:
T = Ti + (robs(Ti) . vearth(T))/c^2 + dtgeo(Ti) + TDB2TDT(Ti)
where robs is the vector from the geocenter to the observer;
vearth is the vector velocity of the earth; and dtgeo is a
correction to convert from the observer's clock to geocentric TT
time. TDB2TDT is the value computed by this function, the
correction to convert from the geocenter to the solar system
barycenter.
As the above equation shows, while this function provides an
important component of the correction, the user must also be
responsible for (a) correcting their times to the geocenter (ie,
by maintaining atomic clock corrections); (b) estimating the
observatory position vector; and and (c) estimating earth's
velocity vector (using JPLEPHINTERP).
Users may note a circularity to the above equation, since
vearth(T) is expressed in terms of the SSB coordinate time. This
appears to be a chicken and egg problem since in order to get the
earth's velocity, the ephemeris time is needed to begin with.
However, to the precision of the above equation, < 25 ns, it is
acceptable to replace vearth(T) with vearth(TT).
The method of computation of TDB2TDT in this function is based on
the analytical formulation by Fairhead, Bretagnon & Lestrade, 1988
(so-called FBL model) and Fairhead & Bretagnon 1990, in terms of
sinusoids of various amplitudes. TDB2TDT has a dominant periodic
component of period 1 year and amplitude 1.7 ms. The set of 791
coefficients used here were drawn from the Princeton pulsar timing
program TEMPO version 11.005 (Taylor & Weisberg 1989).
Because the TDB2TDT quantity is rather expensive to compute but
slowly varying, users may wish to also retrieve the time
derivative using the DERIV keyword, if they have many times to
convert over a short baseline.
Verification
This implementation has been compared against a set of FBL test
data found in the 1996 IERS Conventions, Chapter 11, provided by
T. Fukushima. It has been verified that this routine reproduces
the Fukushima numbers to the accuracy of the table, within
10^{-14} seconds.
Fukushima (1995) has found that the 791-term Fairhead & Bretagnon
analytical approximation use here has a maximum error of 23
nanoseconds in the time range 1980-2000, compared to a numerical
integration. In comparison the truncated 127-term approximation
has an error of ~130 nanoseconds.
PARAMETERS:
JD - Geocentric time TT, scalar or vector, expressed in Julian
days. The actual time used is (JD + TBASE). For maximum
precision, TBASE should be used to express a fixed epoch in
whole day numbers, and JD should express fractional offset
days from that epoch.
KEYWORD PARAMETERS:
TBASE - scalar Julian day of a fixed epoch, which provides the
origin for times passed in JD.
Default: 0
DERIV - upon return, contains the derivative of TDB2TDT in units
of seconds per day. As many derivatives are returned as
values passed in JD.
RETURNS:
The correction offset(s) in units of seconds, to be applied as
noted above.
EXAMPLE:
Find the correction at ephemeris time 2451544.5 (JD):
IDL> print, tdb2tdt(2451544.5d)
-0.00011376314
or 0.11 ms.
REFERENCES:
Princeton TEMPO Program
http://pulsar.princeton.edu/tempo/
FBL Test Data Set
ftp://maia.usno.navy.mil/conventions/chapter11/fbl.results
Fairhead, L. & Bretagnon, P. 1990, A&A, 229, 240
(basis of this routine)
Fairhead, L. Bretagnon, P. & Lestrade, J.-F. 1988, in *The Earth's
Rotation and Reference Frames for Geodesy and Geodynamics*,
ed. A. K. Babcock and G. A. Wilkins, (Dordrecht: Kluwer), p. 419
(original "FBL" paper)
Fukushima, T. 1995, A&A, 294, 895 (error analysis)
Irwin, A. W. & Fukushima, T. 1999, A&A, 348, 642 (error analysis)
Standish, E. M. 1998, A&A, 336, 381 (description of time scales)
Taylor, J. H. & Weisberg, J. M. 1989, ApJ, 345, 434 (pulsar timing)
SEE ALSO
JPLEPHREAD, JPLEPHINTERP, JPLEPHTEST
MODIFICATION HISTORY:
Original logic from Fairhead & Bretagnon, 1990
Drawn from TEMPO v. 11.005, copied 20 Jun 2001
Documented and vectorized, 30 Jun 2001
$Id: tdb2tdt.pro,v 1.4 2001/07/01 07:37:40 craigm Exp $
(See astrolib/pro/tdb2tdt.pro)
TEN()
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NAME:
TEN()
PURPOSE:
Converts a sexagesimal number or string to decimal.
EXPLANATION:
Inverse of the SIXTY() function.
CALLING SEQUENCES:
X = TEN( [ HOUR_OR_DEG, MIN, SEC ] )
X = TEN( HOUR_OR_DEG, MIN, SEC )
X = TEN( [ HOUR_OR_DEG, MIN ] )
X = TEN( HOUR_OR_DEG, MIN )
X = TEN( [ HOUR_OR_DEG ] ) <-- Trivial cases
X = TEN( HOUR_OR_DEG ) <--
or
X = TEN(HRMNSC_STRING)
INPUTS:
HOUR_OR_DEG,MIN,SEC -- Scalars giving sexagesimal quantity in
in order from largest to smallest.
or
HRMNSC_STRING - String giving sexagesmal quantity separated by
spaces or colons e.g. "10 23 34" or "-3:23:45.2"
Any negative values should begin with a minus sign.
OUTPUTS:
Function value returned = double real scalar, decimal equivalent of
input sexigesimal quantity. A minus sign on any nonzero element
of the input vector causes all the elements to be taken as
< 0.
EXAMPLES:
IDL> print,ten(0,-23,34)
--> -0.39277778
IDL> print,ten("-0:23:34")
--> -0.39277778
PROCEDURE:
Mostly involves checking arguments and setting the sign.
The procedure TENV can be used when dealing with a vector of
sexigesimal quantities.
MODIFICATION HISTORY:
Written by R. S. Hill, STX, 21 April 87
Modified to allow non-vector arguments. RSH, STX, 19-OCT-87
Recognize -0.0 W. Landsman/B. Stecklum Dec 2005
Work with string input W. Landsman Dec 2008
(See astrolib/pro/ten.pro)
TENV()
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NAME:
TENV()
PURPOSE:
Converts sexagesimal number or string vector to decimal.
EXPLANATION:
Like TEN() but allows vector input.
CALLING SEQUENCES:
Result = TENV( dd, mm ) ; result = dd + mm/60.
Result = TENV( dd, mm, ss) ; result = dd + mm/60. + ss/3600.
or
Result = TENV(ddmmss_string)
INPUTS:
dd - sexagesimal element(s) corresponding to hours or degrees
mm - sexagesimal element(s) corresponding to minutes
ss - sexagesimal element(s) corresponding to seconds (optional)
The input parameters can be scalars or vectors. However, the
number of elements in each parameter must be the same.
HRMNSC_STRING - String scalar or vector giving sexagesmal quantity
separated by spaces or colons e.g. "10 23 34" or "-3:23:45.2"
Any negative values should begin with a minus sign.
OUTPUTS:
Result - double, decimal equivalent of input sexagesimal
quantities. Same number of elements as the input parameters.
If the nth element in any of the input parameters is negative
then the nth element in Result will also be negative.
EXAMPLE:
If dd = [60,60,0], and mm = [30,-30,-30], then
IDL> Result = TENV(dd,mm) ====> Result = [60.5,-60.5,-0.5]
Alternatively, the input could be written as the string vector
IDL> str = ['60:30','-60:30','-0:30']
IDL> print,tenv(str) ====> Result = [60.5,-60.5,-0.5]
WARNING:
TENV() will recognize floating point values of -0.0 as negative numbers.
However, there is no distinction in the binary representation of -0
and 0 (integer values), and so TENV will treat both values as positive.
PROCEDURES USED:
GETTOK(), REPCHR() for string processing.
PROCEDURE:
Mostly involves checking arguments and setting the sign.
MODIFICATION HISTORY:
Written by W.B. Landsman April, 1991
Recognize -0.0 W. Landsman/B. Stecklum Dec 2005
Work with string input W. Landsman Feb 2009
(See astrolib/pro/tenv.pro)
TEXTCLOSE
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NAME:
TEXTCLOSE
PURPOSE:
Close a text outpu file previously opened with TEXTOPEN
EXPLANATION:
procedure to close file for text output as specifed
by the (non-standard) system variable !TEXTOUT.
CALLING SEQUENCE:
textclose, [ TEXTOUT = ]
KEYWORDS:
textout - Indicates output device that was used by
TEXTOPEN
SIDE EFFECTS:
if !textout is not equal to 5 and the textunit is
opened. Then unit !textunit is closed and released
HISTORY:
D. Lindler Dec. 1986 (Replaces PRTOPEN)
Test if TEXTOUT is a scalar string W. Landsman August 1993
Can't close unit -1 (Standard Output) I. Freedman April 1994
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/textclose.pro)
TEXTOPEN
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NAME:
TEXTOPEN
PURPOSE:
Open a device specified by TEXTOUT with unit !TEXTUNIT
EXPLANATION:
Procedure to open file for text output. The type of output
device (disk file or terminal screen) is specified by the
TEXTOUT keyword or the (nonstandard) system variable !TEXTOUT.
CALLING SEQUENCE:
textopen, program, [ TEXTOUT =, /STDOUT, /SILENT, MORE_SET=, WIDTH= ]
INPUTS:
program - scalar string giving name of program calling textopen
OPTIONAL INPUT KEYWORDS:
TEXTOUT - Integer scalar (0-7) specifying output file/device to be
opened (see below) or scalar string giving name of output file.
If TEXTOUT is not supplied, then the (non-standard) system
variable !TEXTOUT is used.
/SILENT - By default, TEXTOPEN prints an informational message when
opening a file for hardcopy output. Set /SILENT (or !QUIET)
to suppress this message.
/STDOUT - if this keyword is set and non-zero, then the standard output
(unit = -1) is used for TEXTOUT=1 or TEXTOUT=2. The use
of STDOUT has 2 possible advantages:
(1) the output will appear in a journal file
(2) Many Unix machines print spurious control characters when
printing to /dev/tty. These characters are eliminated by
setting /STDOUT
The disadvantage of /STDOUT is that the /MORE option is not
available.
WIDTH - Specify line width for hardcopy output line wrapping (passed onto OPENW).
OPTIONAL OUTPUT KEYWORD:
MORE_SET - Returns 1 if the output unit was opened with /MORE. This
occurs if (1) TEXTOUT = 1 and (2) the device is a tty, and
(3) /STDOUT is not set. User can use the returned value
of MORE_SET to determine whether to end output when user
presses 'Q'.
SIDE EFFECTS:
The following dev/file is opened for output. Different effects
occur depending whether the standard output is a GUI (Macintosh,
Windows, Unix/IDLTool) or a TTY
textout=0 Nowhere
textout=1 if a TTY then TERMINAL using /more option
otherwise standard (Unit=-1) output
textout=2 if a TTY then TERMINAL without /more option
otherwise standard (Unit=-1) output
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file
textout=7 same as 3 but text is appended to .prt
file if it already exists.
textout = filename (default extension of .prt)
The unit to be opened is obtained with the procedure GET_LUN
unless !TEXTOUT=5. The unit number is placed in system variable
!TEXTUNIT. For !TEXTOUT=5 the user must set !TEXTUNIT to the
appropriate unit number.
NOTES:
When printing to a TTY terminal, the output will *not* appear in an
IDL JOURNAL session, unlike text printed with the PRINT command.
NON-STANDARD SYSTEM VARIABLES:
TEXTOPEN will automatically define the following system variables if
they are not previously defined:
DEFSYSV,'!TEXTOUT',1
DEFSYSV,'!TEXTUNIT',0
HISTORY:
D. Lindler Dec. 1986
Keyword textout added, J. Isensee, July, 1990
Made transportable, D. Neill, April, 1991
Trim input PROGRAM string W. Landsman Feb 1993
Don't modify TEXTOUT value W. Landsman Aug 1993
Modified for MacOS I. Freedman April 1994
Modified for output terminals without a TTY W. Landsman August 1995
Added /STDOUT keyword W. Landsman April 1996
added textout=7 option, D. Lindler, July, 1996
Exit with RETURN instead of RETALL W. Landsman June 1999
In IDL V5.4 filepath(/TERMINAL) not allowed in the IDLDE WL August 2001
Added MORE_SET output keyword W.Landsman January 2002
Added /SILENT keyword W. Landsman June 2002
Define !TEXTOUT and !TEXTUNIT if needed. R. Sterner, 2002 Aug 27
Return Calling Sequence if no parameters supplied W.Landsman Nov 2002
Remove VMS specific code W. Landsman Sep 2006
Make sure MORE_SET is always defined W. Landsman Jan 2007
Added WIDTH keyword J. Bailin Nov 2010
Use V6.0 notation W. Landsman April 2011
(See astrolib/pro/textopen.pro)
TICLABELS
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NAME:
TICLABELS
PURPOSE:
Create tic labels for labeling astronomical images.
EXPLANATION:
Used to display images with right ascension or declination
axes. This routine creates labels for already determined tic
marks (every other tic mark by default)
CALLING SEQUENCE:
TICLABELS, minval, numtics, incr, ticlabs, [ RA = ,DELTA = ]
INPUTS:
minval - minimum value for labels (degrees)
numtics - number of tic marks
incr - increment in minutes for labels
OUTPUTS:
ticlabs - array of charater string labels
OPTIONAL INPUT KEYWORDS:
/RA - if this keyword is set then the grid axis is assumed to be
a Right Ascension. Otherwise a declination axis is assumed
DELTA - Scalar specifying spacing of labels. The default is
DELTA = 2 which means that a label is made for every other tic
mark. Set DELTA=1 to create a label for every tic mark.
FONT - scalar font graphics keyword (-1,0 or 1) for text
PROCEDURES USED:
RADEC
RESTRICTIONS:
Invalid for wide field (> 2 degree) images since it assumes that a
fixed interval in Y (or X) corresponds to a fixed interval in Dec
(or RA)
REVISON HISTORY:
written by B. Pfarr, 4/15/87
Added DELTA keywrd for compatibility with IMCONTOUR W. Landsman Nov 1991
Added nicer hms and dms symbols when using native PS fonts Deutsch 11/92
Added Patch for bug in IDL <2.4.0 as explained in NOTES E. Deutsch 11/92
Fix when crossing 0 dec or 24h RA
Fix DELTA keyword so that it behaves according to the documentation
W. Landsman Hughes STX, Nov 95
Allow sub arcsecond formatting W. Landsman May 2000
Better formatting for non-unity DELTA values W. Landsman July 2004
Allow FONT keyword to be passed. T. Robishaw Apr. 2006
Write 0h rather than 24h W. L. August 2008
Fix problem when tic values is exactly 0 degrees Mar 2012
Only modulo 24 when /RA is set WL. October 2012
(See astrolib/pro/ticlabels.pro)
TICPOS
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NAME:
TICPOS
PURPOSE:
Specify distance between tic marks for astronomical coordinate overlays
EXPLANATION:
User inputs number an approximate distance
between tic marks, and the axis length in degrees. TICPOS will return
a distance between tic marks such that the separation is a round
multiple in arc seconds, arc minutes, or degrees
CALLING SEQUENCE:
TICPOS, deglen, pixlen, ticsize, incr, units
INPUTS:
deglen - length of axis in DEGREES
pixlen - length of axis in plotting units (pixels)
ticsize - distance between tic marks (pixels). This value will be
adjusted by TICPOS such that the distance corresponds to
a round multiple in the astronomical coordinate.
OUTPUTS:
ticsize - distance between tic marks (pixels), positive scalar
incr - incremental value for tic marks in round units given
by the UNITS parameter
units - string giving units of ticsize, either 'ARC SECONDS',
'ARC MINUTES', or 'DEGREES'
EXAMPLE:
Suppose a 512 x 512 image array corresponds to 0.2 x 0.2 degrees on
the sky. A tic mark is desired in round angular units, approximately
every 75 pixels.
IDL> ticsize = 75
IDL> TICPOS,0.2,512,ticsize,incr,units
==> ticsize = 85.333, incr = 2. units = 'Arc Minutes'
i.e. a good tic mark spacing is every 2 arc minutes, corresponding
to 85.333 pixels.
REVISON HISTORY:
written by W. Landsman November, 1988
Converted to IDL V5.0 W. Landsman September 1997
Don't use all capital letters W. Landsman May 2003
Fix case where incr crosses degree/minute or minute/degree boundary
A. Mortier/W.Landsman April 2005
(See astrolib/pro/ticpos.pro)
TICS
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NAME:
TICS
PURPOSE:
Compute a nice increment between tic marks for astronomical images.
EXPLANATION:
For use in labelling a displayed image with right ascension
or declination axes. An approximate distance between tic
marks is input, and a new value is computed such that the
distance between tic marks is in simple increments of the
tic label values.
CALLING SEQUENCE:
tics, radec_min, radec_max, numx, ticsize, incr, [ /RA ]
INPUTS:
radec_min - minimum axis value (degrees)
radec_max - maximum axis value (degrees)
numx - number of pixels in x direction
INPUT/OUTPUT
ticsize - distance between tic marks (pixels)
OUTPUTS:
incr - incremental value for tic labels (in minutes of
time for R.A., minutes of arc for dec.)
REVISON HISTORY:
written by B. Pfarr, 4/14/87
Added some more tick precision (i.e. 1 & 2 seconds in case:) EWD May92
Added sub arcsecond tick precision W. Landsman May 2000
Plate scale off by 1 pixel W. Landsman July 2004
(See astrolib/pro/tics.pro)
TIC_ONE
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NAME:
TIC_ONE
PURPOSE:
Determine the position of the first tic mark for astronomical images.
EXPLANATION:
For use in labelling images with right ascension
and declination axes. This routine determines the
position in pixels of the first tic.
CALLING SEQUENCE:
tic_one, zmin, pixx, incr, min2, tic1, [RA = ]
INPUTS:
zmin - astronomical coordinate value at axis zero point (degrees
or hours)
pixx - distance in pixels between tic marks (usually obtained from TICS)
incr - increment in minutes for labels (usually an even number obtained
from the procedure TICS)
OUTPUTS:
min2 - astronomical coordinate value at first tic mark
tic1 - position in pixels of first tic mark
EXAMPLE:
Suppose a declination axis has a value of 30.2345 degrees at its
zero point. A tic mark is desired every 10 arc minutes, which
corresponds to 12.74 pixels. Then
IDL> TIC_ONE, 30.2345, 1, 12.74, min2, tic1
yields values of min2 = 30.333 and tic1 = 5.74, i.e. the first tic
mark should be labeled 30 deg 20 minutes and be placed at pixel value
5.74
REVISION HISTORY:
by B. Pfarr, 4/15/87
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/tic_one.pro)
TO_HEX
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NAME:
TO_HEX
PURPOSE:
Translate a non-negative decimal integer to a hexadecimal string
CALLING SEQUENCE:
HEX = TO_HEX( D, [ NCHAR ] )
INPUTS:
D - non-negative decimal integer, scalar or vector. If input as a
string, (e.g. '32') then all leading blanks are removed.
OPTIONAL INPUT:
NCHAR - number of characters in the output hexadecimal string.
If not supplied, then the hex string will contain no
leading zeros.
OUTPUT:
HEX - hexadecimal translation of input integer, string
EXAMPLES:
IDL> A = TO_HEX([11,16]) ==> A = ['B','10']
IDL> A = TO_HEX(100,3) ==> A = '064'
METHOD:
The hexadecimal format code '(Z)' is used to convert. No parameter
checking is done.
PROCEDURES CALLED:
None.
REVISION HISTORY:
Written W. Landsman November, 1990
Converted to IDL V5.0 W. Landsman September 1997
Use FSTRING() for more than 1024 values March 2000
Assume since V5.4, omit FSTRING() call April 2006
(See astrolib/pro/to_hex.pro)
TRANSFORM_COEFF()
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NAME:
TRANSFORM_COEFF()
PURPOSE:
Compute new polynomial coefficients under a linear transformation
EXPLANATION:
Suppose one has a (nonlinear) polynomial (similar to the POLY() function)
y = C[0] + C[1]*x + C[2]*x^2 + C[3]*x^3 + ...
and one has a linear transformation in X
x = alpha*x' + beta
This function computes the new polynomial coefficients under the linear
transformation.
CALLING SEQUENCE:
newcoeff = TRANSFORM_COEFF( coeff, alpha, beta)
INPUTS:
Coeff - vector of polynomial coefficients (as with POLY()). The
degree of the polynomial is N_elements(coeff) - 1
Alpha, Beta - numeric scalars defining the linear transformation in X
OUTPUTS:
NewCoeff - Vector (same size as Coeff) giving the new polyomial
coefficients
EXAMPLE:
Suppose one has polynomial mapping a nonlinear distortion in the X
direction of a spectrum
y = 0.2 + 1.1*x + 0.1*x^2
if one rebins the spectrum to half the size then the linear transformation
is x = 2.*x'
so alpha = 2 and beta = 0
The new coefficients are
IDL> print, transform_coeff([0.2,1.1,0.1],2.,0)
==> [0.2, 2.2, 0.4]
METHOD:
Performs a binomial expansion of the polynomial and collect like terms
groups.google.com/group/comp.lang.idl-pvwave/msg/11132d96d9c0f93d?hl=en&
REVISION HISTORY:
Written W. Landsman December 2007
(See astrolib/pro/transform_coeff.pro)
TRAPZD
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NAME:
TRAPZD
PURPOSE:
Compute the nth stage of refinement of an extended trapezoidal rule.
EXPLANATION:
This procedure is called by QSIMP and QTRAP. Algorithm from Numerical
Recipes, Section 4.2. TRAPZD is meant to be called iteratively from
a higher level procedure.
CALLING SEQUENCE:
TRAPZD, func, A, B, S, step, [ _EXTRA = ]
INPUTS:
func - scalar string giving name of function to be integrated. This
must be a function of one variable.
A,B - scalars giving the limits of the integration
INPUT-OUTPUT:
S - scalar giving the total sum from the previous iterations on
input and the refined sum after the current iteration on output.
step - LONG scalar giving the number of points at which to compute the
function for the current iteration. If step is not defined on
input, then S is intialized using the average of the endpoints
of limits of integration.
OPTIONAL INPUT KEYWORDS:
Any supplied keywords will be passed to the user function via the
_EXTRA facility.
NOTES:
(1) TRAPZD will check for math errors (except for underflow) when
computing the function at the endpoints, but not on subsequent
iterations.
(2) TRAPZD always uses double precision to sum the function values
but the call to the user-supplied function is double precision only if
one of the limits A or B is double precision.
REVISION HISTORY:
Written W. Landsman August, 1991
Always use double precision for TOTAL March, 1996
Pass keyword to function via _EXTRA facility W. Landsman July 1999
Don't check for floating underflow W.Landsman April 2008
(See astrolib/pro/trapzd.pro)
TSC
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NAME:
TSC
PURPOSE:
Interpolate an irregularly sampled field using a Triangular Shaped Cloud
EXPLANATION:
This function interpolates an irregularly sampled field to a
regular grid using Triangular Shaped Cloud (nearest grid point
gets weight 0.75-dx^2, points before and after nearest grid
points get weight 0.5*(1.5-dx)^2, where dx is the distance
from the sample to the grid point in units of the cell size).
CATEGORY:
Mathematical functions, Interpolation
CALLING SEQUENCE:
Result = TSC, VALUE, POSX, NX[, POSY, NY, POSZ, NZ,
AVERAGE = average, WRAPAROUND = wraparound,
ISOLATED = isolated, NO_MESSAGE = no_message]
INPUTS:
VALUE: Array of sample weights (field values). For e.g. a
temperature field this would be the temperature and the
keyword AVERAGE should be set. For e.g. a density field
this could be either the particle mass (AVERAGE should
not be set) or the density (AVERAGE should be set).
POSX: Array of X coordinates of field samples, unit indices: [0,NX>.
NX: Desired number of grid points in X-direction.
OPTIONAL INPUTS:
POSY: Array of Y coordinates of field samples, unit indices: [0,NY>.
NY: Desired number of grid points in Y-direction.
POSZ: Array of Z coordinates of field samples, unit indices: [0,NZ>.
NZ: Desired number of grid points in Z-direction.
KEYWORD PARAMETERS:
AVERAGE: Set this keyword if the nodes contain field samples
(e.g. a temperature field). The value at each grid
point will then be the weighted average of all the
samples allocated to it. If this keyword is not
set, the value at each grid point will be the
weighted sum of all the nodes allocated to it
(e.g. for a density field from a distribution of
particles). (D=0).
WRAPAROUND: Set this keyword if you want the first grid point
to contain samples of both sides of the volume
(see below).
ISOLATED: Set this keyword if the data is isolated, i.e. not
periodic. In that case total `mass' is not conserved.
This keyword cannot be used in combination with the
keyword WRAPAROUND.
NO_MESSAGE: Suppress informational messages.
Example of default allocation of nearest grid points: n0=4, *=gridpoint.
0 1 2 3 Index of gridpoints
* * * * Grid points
|---|---|---|---| Range allocated to gridpoints ([0.0,1.0> --> 0, etc.)
0 1 2 3 4 posx
Example of ngp allocation for WRAPAROUND: n0=4, *=gridpoint.
0 1 2 3 Index of gridpoints
* * * * Grid points
|---|---|---|---|-- Range allocated to gridpoints ([0.5,1.5> --> 1, etc.)
0 1 2 3 4=0 posx
OUTPUTS:
Prints that a TSC interpolation is being performed of x
samples to y grid points, unless NO_MESSAGE is set.
RESTRICTIONS:
Field data is assumed to be periodic with the sampled volume
the basic cell, unless ISOLATED is set.
All input arrays must have the same dimensions.
Postition coordinates should be in `index units' of the
desired grid: POSX=[0,NX>, etc.
Keywords ISOLATED and WRAPAROUND cannot both be set.
PROCEDURE:
Nearest grid point is determined for each sample.
TSC weights are computed for each sample.
Samples are interpolated to the grid.
Grid point values are computed (sum or average of samples).
EXAMPLE:
nx=20
ny=10
posx=randomu(s,1000)
posy=randomu(s,1000)
value=posx^2+posy^2
field=tsc(value,posx*nx,nx,posy*ny,ny,/average)
surface,field,/lego
NOTES:
Use csc.pro or ngp.pro for lower order interpolation schemes. A
standard reference for these interpolation methods is: R.W. Hockney
and J.W. Eastwood, Computer Simulations Using Particles (New York:
McGraw-Hill, 1981).
MODIFICATION HISTORY:
Written by Joop Schaye, Feb 1999.
Check for overflow for large dimensions P. Riley/W. Landsman Dec. 1999
(See astrolib/pro/tsc.pro)
TSUM
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NAME:
TSUM
PURPOSE:
Trapezoidal summation of the area under a curve.
EXPLANATION:
Adapted from the procedure INTEG in the IUE procedure library.
CALLING SEQUENCE:
Result = TSUM(y)
or
Result = TSUM( x, y, [ imin, imax ] )
INPUTS:
x = array containing monotonic independent variable. If omitted, then
x is assumed to contain the index of the y variable.
x = lindgen( N_elements(y) ).
y = array containing dependent variable y = f(x)
OPTIONAL INPUTS:
imin = scalar index of x array at which to begin the integration
If omitted, then summation starts at x[0].
imax = scalar index of x value at which to end the integration
If omitted then the integration ends at x[npts-1].
OUTPUTS:
result = area under the curve y=f(x) between x[imin] and x[imax].
EXAMPLE:
IDL> x = [0.0,0.1,0.14,0.3]
IDL> y = sin(x)
IDL> print,tsum(x,y) ===> 0.0445843
In this example, the exact curve can be computed analytically as
1.0 - cos(0.3) = 0.0446635
PROCEDURE:
The area is determined of individual trapezoids defined by x[i],
x[i+1], y[i] and y[i+1].
If the data is known to be at all smooth, then a more accurate
integration can be found by interpolation prior to the trapezoidal
sums, for example, by the standard IDL User Library int_tabulated.pro.
MODIFICATION HISTORY:
Written, W.B. Landsman, STI Corp. May 1986
Modified so X is not altered in a one parameter call Jan 1990
Converted to IDL V5.0 W. Landsman September 1997
Allow non-integer values of imin and imax W. Landsman April 2001
Fix problem if only 1 parameter supplied W. Landsman June 2002
(See astrolib/pro/tsum.pro)
TVBOX
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NAME:
TVBOX
PURPOSE:
Draw a box(es) or rectangle(s) of specified width
EXPLANATION:
Positions can be specified either by the cursor position or by
supplying a vector of X,Y positions. By default, TVBOX now
(since Jan 2012) assumes data coordinates if !X.crange is set.
CALLING SEQUENCE:
TVBOX, width, [ x, y, color, /DATA, ANGLE= ,COLOR =, _EXTRA = ]
INPUTS:
WIDTH - either a scalar giving the width of a box, or a 2 element
vector giving the length and width of a rectangle.
OPTIONAL INPUTS:
X - x position for box center, scalar or vector
Y - y position for box center, scalar or vector. If vector, then Y
must have the same number of elements as X
Positions are specified in device coordinates unless /DATA is set
If X and Y are not specified, and device has a cursor, then
TVBOX will draw a box at current cursor position
COLOR - String or integer specifying the color to draw the box(es)
If COLORS is a scalar then all boxes are drawn with the same
color value. Otherwise, the Nth box is drawn with the
Nth value of color. Color can also be specified as
string (e.g.'red'). See cgCOLOR for a list of available
color names. Default = "opposite".
OUTPUTS:
None
OPTIONAL KEYWORD INPUTS:
ANGLE - numeric scalar specifying the clockwise rotation of
the boxes or rectangles.
COLOR - Scalar or vector, overrides the COLOR input parameter
Color can be specified as a string (e.g. 'red') or intensity
value. See cgCOLOR() for a list of color names.
Default = 'opposite' (i.e. color opposite the background).
/DATA - if this keyword is set and non-zero, then the box width and
X,Y position center are interpreted as being in DATA
coordinates. Note that data coordinates must be previously
defined (with a PLOT or CONTOUR call). The default
is to assume data coordinates if !X.CRANGE is set. Force
device coordinates by setting DATA = 0 or /DEVICE
/DEVICE Set this keyword to force use of device coordinates
/FILL - If set, fill the box using cgCOLORFILL
/SQUARE - If set, then a square is drawn, even if in data coordinates
with unequal X and Y axes. The X width is used for the
square width, and the Y width is ignored.
Any keyword recognized by cgPLOTS (or cgCOLORFILL if /FILL is set)
is also recognized by TVBOX.
In particular, the linestyle, thickness and clipping of the boxes
is controlled by the LINESTYLE, THICK and NOCLIP keywords.
(Clipping is turned off by default, set NOCLIP=0 to activate it.)
If /FILL is set then available keywords include LINE_FILL and
FILL_PATTERN.
SIDE EFFECTS:
A square or rectangle will be drawn on the device
For best results WIDTH should be odd when using the default DEVICE
coordinates. (If WIDTH is even, the actual size of the box will be
WIDTH + 1, so that box remains centered.)
EXAMPLES:
(1) Draw a double thick box of width 13, centered at 221,256 in the
currently active window
IDL> tvbox, 13, 221, 256, thick=2
(2) Overlay a "slit" with dimension 52" x 2" on a previously displayed
image at a position angle (East of North) of 32 degrees. The
slit is to be centered at XC, YC and the plate scale
arcsec_per_pixel is known.
IDL> w = [2.,52.]/arcsec_per_pixel ;Convert slit size to pixel units
IDL> tvbox,w,XC,YC,ang=-32 ;Draw slit
RESTRICTIONS:
Allows use of only device (default) or data (if /DATA is set)
coordinates. Normalized coordinates are not allowed
PROCEDURES USED:
cgpolygon, zparcheck
REVISON HISTORY:
Written, W. Landsman STX Co. 10-6-87
Modified to take vector arguments. Greg Hennessy Mar 1991
Fixed centering of odd width W. Landsman Sep. 1991
Let the user specify COLOR=0, accept vector color, W. Landsman Nov. 1995
Fixed typo in _EXTRA keyword W. Landsman August 1997
Added ANGLE keyword W.Landsman February 2000
Make sure ANGLE is a scalar W. Landsman September 2001
Don't round coordinates if /DATA is set. M. Perrin August 2005
Use STRICT_EXTRA to flag valid keywords W. Landsman Sep 2005
Check that width has only 1 or 2 elements W. Landsman August 2010
Use Coyote Graphcis W. Landsman February 2011
Added /FILL keyword W. Landsman July 2011
Default to data coordinates if !X.crange present WL Jan 2012
Added Square keyword WL. April 2012
(See astrolib/pro/tvbox.pro)
TVCIRCLE
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NAME:
TVCIRCLE
PURPOSE:
Draw circle(s) of specified radius at specified position(s)
EXPLANATION:
If a position is not specified, and device has a cursor, then a circle
is drawn at the current cursor position. By default, TVCIRCLE now
(since Jan 2012) assumes data coordinates if !X.crange is set.
CALLING SEQUENCE:
TVCIRCLE, rad, x, y, color, [ /DATA, /FILL, _EXTRA = ]
INPUTS:
RAD - radius of circle(s) to be drawn, positive numeric scalar
OPTIONAL INPUT:
X - x position for circle center, vector or scalar
Y - y position for circle center, vector or scalar
If X and Y are not specified, and the device has a cursor,
then program will draw a circle at the current cursor position
COLOR - color name or intensity value(s) (0 - !D.N_COLORS) used to draw
the circle(s). If COLOR is a scalar then all circles are drawn
with the same color value. Otherwise, the Nth circle is drawn
with the Nth value of color. See cgCOLOR() for a list of color
names. Default = 'opposite' (i.e. color opposite the
background).
OPTIONAL KEYWORD INPUTS:
/DATA - if this keyword is set and non-zero, then the circle width and
X,Y position center are interpreted as being in DATA
coordinates. Note that data coordinates must be previously
defined (with a PLOT or CONTOUR call). TVCIRCLE will
internally convert to device coordinates before drawing the
circle, in order to maintain optimal smoothness. The default
is to assume data coordinates if !X.CRANGE is set. Force
device coordinates by setting DATA = 0 or /DEVICE
/DEVICE - If set, then force use of device coordinates..
/FILL - If set, fill the circle using cgCOLORFILL
Any keyword recognized by cgPLOTS (or cgCOLORFILL if /FILL is
set) is also recognized by TVCIRCLE. In particular, the color,
linestyle, thickness and clipping of the circles are controlled
by the COLOR, LINESTYLE, THICK and NOCLIP keywords. (Clipping
is turned off by default, set NOCLIP=0 to activate it.)
If /FILL is set then available keywords are LINE_FILL and
FILL_PATTERN.
OUTPUTS:
None
RESTRICTIONS:
(1) Some round-off error may occur when non-integral values are
supplied for both the radius and the center coordinates
(2) TVCIRCLE does not accept /NORMAL coordinates.
(3) TVCIRCLE always draws a circle --- even when in data coordinates
and the X and Y data scales are unequal. (The X data scale is
used to define the circle radius.) If this is not the behaviour
you want, then use TVELLIPSE instead.
EXAMPLE:
(1) Draw circles of radius 9 pixels at the positions specified by
X,Y vectors, using double thickness lines
IDL> tvcircle, 9, x, y, THICK = 2
Now fill in the circles using the LINE_FILL method
IDL> tvcircle, 9, x, y, /FILL, /LINE_FILL
METHOD:
The method used is that of Michener's, modified to take into account
the fact that IDL plots arrays faster than single points. See
"Fundamental of Interactive Computer Graphics" by Foley and Van Dam"
p. 445 for the algorithm.
REVISON HISTORY:
Original version written by B. Pfarr STX 10-88
Major rewrite adapted from CIRCLE by Allyn Saroyan LNLL
Wayne Landsman STX Sep. 91
Added DATA keyword Wayne Landsman HSTX June 1993
Added FILL keyword. R. S. Hill, HSTX, 4-Nov-1993
Always convert to device coords, add _EXTRA keyword, allow vector
colors. Wayne Landsman, HSTX, May 1995
Allow one to set COLOR = 0, W. Landsman, HSTX, November 1995
Check if data axes reversed. P. Mangifico, W. Landsman May 1996
Use strict_extra to check input keywords W. Landsman July 2005
Update documentation to note NOCLIP=0 option W.L. Oct. 2006
Make all integers default to LONG W. Landsman Dec 2006
Use Coyote Graphics procedures W. Landsman Feb 2011
Default to data coordinates if !X.crange present WL Jan 2012
Add /DEVICE coords, fix Jan 2012 update. Mar 2012
(See astrolib/pro/tvcircle.pro)
TVELLIPSE
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NAME:
TVELLIPSE
PURPOSE:
Draw an ellipse on the current graphics device.
CALLING SEQUENCE:
TVELLIPSE, rmax, rmin, xc, yc, [ pos_ang, color, COLOR= ,/DATA, NPOINTS=
LINESTYLE=, THICK=, /MAJOR, /MINOR ]
INPUTS:
RMAX,RMIN - Scalars giving the semi-major and semi-minor axes of
the ellipse
OPTIONAL INPUTS:
XC,YC - Scalars giving the position on the TV of the ellipse center
If not supplied (or if XC, YC are negative and /DATA is not
set), and an interactive graphics device (e.g. not postscript)
is set, then the user will be prompted for X,Y
POS_ANG - Position angle of the major axis, measured counter-clockwise
from the X axis. Default is 0.
COLOR - Scalar integer or string specifying color to draw ellipse.
See cgcolor.pro for a list of possible color names
OPTIONAL KEYWORD INPUT:
COLOR - Intensity value or color name used to draw the circle,
overrides parameter value. Default = 'opposite'
See cgCOLOR() for a list of color names.;
/DATA - if this keyword is set and non-zero, then the ellipse radii and
X,Y position center are interpreted as being in DATA
coordinates. Note that the data coordinates must have been
previously defined (with a PLOT or CONTOUR call). The default
is to assume data coordinates if !X.CRANGE has been set by a
previous plot. Force device coordinates by setting DATA = 0.
/DEVICE - Set to force use of device coordinates.
/FILL - If set, then fill the ellipse using cgCOLORFILL
NPOINTS - Number of points to connect to draw ellipse, default = 120
Increase this value to improve smoothness
/MAJOR - Plot a line along the ellipse's major axis
/MINOR - Plot a line along the ellipse's minor axis
Any keyword recognized by cgPLOTS is also recognized by TVELLIPSE.
In particular, the color, linestyle, thickness and clipping of
the ellipses are controlled by the COLOR, LINESTYLE, THICK and
NOCLIP keywords. (Clipping is turned off by default, set
NOCLIP=0 to activate it.) If /FILL is set then available
keywords include LINE_FILL and FILL_PATTERN.
RESTRICTIONS:
TVELLIPSE does not check whether the ellipse is within the boundaries
of the window.
The ellipse is evaluated at NPOINTS (default = 120) points and
connected by straight lines, rather than using the more sophisticated
algorithm used by TVCIRCLE
TVELLIPSE does not accept normalized coordinates.
TVELLIPSE is not vectorized; it only draws one ellipse at a time
EXAMPLE:
Draw an ellipse of semi-major axis 50 pixels, minor axis 30
pixels, centered on (250,100), with the major axis inclined 25
degrees counter-clockwise from the X axis. Use a double thickness
line and device coordinates
IDL> tvellipse,50,30,250,100,25,thick=2,/device
NOTES:
Note that the position angle for TVELLIPSE (counter-clockwise from
the X axis) differs from the astronomical position angle
(counter-clockwise from the Y axis).
REVISION HISTORY:
Written W. Landsman STX July, 1989
Converted to use with a workstation. M. Greason, STX, June 1990
LINESTYLE keyword, evaluate at 120 points, W. Landsman HSTX Nov 1995
Added NPOINTS keyword, fixed /DATA keyword W. Landsman HSTX Jan 1996
Check for reversed /DATA coordinates P. Mangiafico, W.Landsman May 1996
Work correctly when X & Y data scales are unequal December 1998
Removed cursor input when -ve coords are entered with /data
keyword set P. Maxted, Keele, 2002
Use _EXTRA keywords including NOCLIP W. Landsman October 2006
Add plotting of major and minor axes and /MAJOR, /MINOR keywords;
fixed description of RMAX,RMIN (semi-axes). J. Guerber Feb. 2007
Update to use Coyote graphics W. Landsman Feb 2011
Default to data coordinates if a previous plot has been made
(X.crange is non-zero) W. Landsman Jan 2012
Added /DEVICE keyword W. Landsman Mar 2012
Added /FILL keyword W. Landsman Mar 2012
(See astrolib/pro/tvellipse.pro)
TVLASER
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NAME:
TVLASER
PURPOSE:
Prints screen or image array onto a Postscript file or printer.
Information from FITS header is optionally used for labeling.
CALLING SEQUENCE:
TVLASER, [header, Image, BARPOS = ,CARROWS =, CLABELS = ,/COLORPS,
COMMENTS = ,CSIZE = ,CTITLE = , DX = , DY =, /ENCAP, FILENAME =
HEADER = ,/HELP, IMAGEOUT = ,/INTERP, /MAGNIFY, /NoCLOSE,
/NoDELETE, /NO_PERS_INFO, /NoEIGHT, /NoPRINT, /NoRETAIN,
/PORTRAIT, PRINTER = , /REVERSE, /SCALE, TITLE = , /TrueColor,
XDIM=, XSTART=, YDIM=, YSTART=, BOTTOMDW=, NCOLORSDW= ]
Note that the calling sequence was changed in May 1997
OPTIONAL INPUTS:
HEADER - FITS header string array. Object and astrometric info from
the FITS header will be used for labeling, if available
IMAGE - if an array is passed through this parameter, then this image
will be used rather than reading off the current window. This
allows easy use of large images. It is usually preferable
to optimally byte scale IMAGE before supplying it to TVLASER
OPTIONAL KEYWORD INPUT PARAMETERS:
BARPOS - A four- or five-element vector giving the position and
orientation of the color bar. The first four elements
[X0,Y0,XSize,YSize] indicate the position and size of the color
bar in INCHES, relative to origin of the displayed image.
(X0,Y0) are the position of the lower left corner and
(XSize,YSize) are the width and height. The fifth element is
optional, and if present, the color bar will be printed
horizontally rather than vertically. If BARPOS is set to
anything but a four- or five-element vector, the bar is NOT
printed. The default value is BARPOS = [-0.25, 0.0, 0.2, 2.0]
BOTTOMDW - The lowest value to use in building the density
wedge. Used with NCOLORSDW. Compatible with BOTTOM and
NCOLORS keywords of XLOADCT.
CARROWS - The color to print the North-East arrows. Default is dark.
Three types of values can be passed:
SCALAR: that value's color in the current color table
3-ELEMENT VECTOR: the color will be [R,G,B]
STRING: A letter indicating the color. Valid names are:
'W' (white), 'D' (dark/black), 'R' (red), 'G' (green),
'B' (blue), 'T' (turquoise), 'V' (violet), 'Y' (yellow),
If the keyword is set to a value of -1, the arrows are
NOT printed.
COLORPS - If present and non-zero, the idl.ps file is written using
color postscript.
COMMENTS - A string that will be included in the comment line below the
image. For multi-line comments you can either use "!C" in the
string as a carriage return {although the vertical spacing
might be a little off} or, preferably, make the COMMENTS a
string array with each line as a separate element.
CLABELS - Color to print the labels, same format as for CARROWS.
CSIZE - Color to print the size-scale bar and label, same format as for
CARROWS.
CTITLE - Color to print the title, same format as for CARROWS.
DX,DY - offsets in INCHES added to the position of the figure on the
paper. As is the case for the device keywords XOFFSET and
YOFFSET, when in landscape mode DX and DY are the same
*relative to the paper*, not relative to the plot (e.g., DX is
the horizontal offset in portrait mode, but the *vertical*
offset in landscape mode).
ENCAP - If present and non-zero, the IDL.PS file is written in
encapsulated postscript for import into LaTeX documents
FILENAME - scalar string giving name of output postscript file.
Default is idl.ps. Automatically sets /NODELETE
HEADER = FITS header. This is an alternative to supplying the FITS
header in the first parameter.
HELP - print out the sytax for this procedure.
INTERP - If present and non-zero, current color table will be
interpolated to fill the full range of the PostScript color
table (256 colors). Otherwise, the current color table will be
directly copied. You probably will want to use this if you
are using IMAGE keyword and a shared color table.
MAGNIFY - The net magnification of the entire figure. At this point,
the figure is not automatically centered on the paper if the
value of MAGNIFY is not equal to 1, but the DX and DY keywords
can be used to shift location. For example, to fit a full plot
on the printable area (8.5x8.5 inches) of the Tek PhaserIISD
color printer use: MAGNIFY=0.8, DX=0.5, DY=0.5.;
NCOLORSDW - The number of values to include in the density
wedge. Used with BOTTOMDW. Compatible with
BOTTOM/NCOLORS keywords of XLOADCT.
NoCLOSE - If present and non-zero, then the postscript file is not
closed (or printed), the device is set to 'PS', and the data
coordinate system is set to match the image size. This allows the
user to add additional plotting commands before printing. For
example, to include a 15 pixel circle around a source at
coordinates (150,160), around an image, im, with FITS header
array, h
IDL> tvlaser,h,im,/NoClose ;Write image & annotation
IDL> tvcircle,15,150,160,/data ;Draw circle
IDL> device,/close ;Close postscript file & print
NoDELETE - If present and non-zero, the postscript file is kept AND is
also sent to the printer
NoEIGHT - if set then only four bits sent to printer (saves space)
NO_PERS_INFO - if present and non-zero, output notation will NOT
include date/user block of information.
NoPRINT - If present and non-zero, the output is sent to a file (default
name 'idl.ps'), which is NOT deleted and is NOT sent to the
printer.
NoRETAIN - In order to avoid possible problems when using TVRD with
an obscured window, TVLASER will first copy the current window
to a temporary RETAIN=2 window. Set /NORETAIN to skip this
step and improve performance
PORTRAIT - if present and non-zero, the printer results will be in
portrait format; otherwise, they will be in landscape format.
If labels are requested, image will be in portrait mode,
regardless
PRINTER - scalar string giving the OS command to send a the postscript
file to the printer. Under Unix, the default value of PRINTER
is 'lpr ' while for other OS it is 'print '
REVERSE - if present and non-zero, color table will be fliped, so black
and white are reversed.
SCALE - if present and non-zero, image will be bytscaled before being
sent to postscript file.
TITLE - if present and non-zero, the string entered here will be the
title of the picture. Default is the OBJECT field in the
header (if present).
TRUECOLOR - if present and non-zero, the postscript file is created
using the truecolor switch (i.e. true=3). The colorbar is
not displayed in this mode.
XDIM,YDIM - Number of pixels. Default is from !d.x_size and !d.y_size,
or size of image if passed with IMAGE keyword.
XSTART,YSTART - lower left corner (default of (0,0))
OPTIONAL KEYWORD OUTPUT PARAMETER
IMAGEOUT = the image byte array actually sent to the postscript file.
SIDE EFFECTS:
A postscript file is created in the current directory. User must have
write privileges in the current directory. The file is named idl.ps
unless the FILENAME keyword is given. The file is directed to the
printer unless the /ENCAP, /NoCLOSE, or /NOPRINT keywords are given.
After printing, the file is deleted unless the /NODELETE or FILENAME
keywords are given.
PROCEDURE:
Read display or take IMAGE and then redisplay into a postscript file.
If a header exists, printout header information. If header has
astrometry, then print out orientation and scale information.
PROCEDURES USED:
ARROWS, EXTAST, FDECOMP, GETROT, PIXCOLOR, SXPAR(), XYAD, ZPARCHECK
*EXAMPLE:
1) Send a true color image (xsize,ysize,3) to a printer (i.e. print23l),
tvlaser,huv,cpic,/colorps,/truecolor,printer="print23l"
% TVLASER: Now printing image: $print23l idl.ps
MODIFICATION HISTORY:
Major rewrite from UIT version W. Landsman Dec 94
Massive rewrite. Added North-East arrows, pixel scale bar, color bar,
and keywords DX, DY, MAGNIFY, INTERP, HELP, and COMMENTS.
Created ablility to define colors for annotation and
text. Repositioned text labels. J.Wm.Parker, HITC, 5/95
Make Header and Image parameters instead of keywords. Add PRINTER
keyword. Include alternate FITS keywords. W. Landsman May 97
Copy to a RETAIN=2 window, work without FITS header W. Landsman June 97
Cleaner output when no astrometry in header W. Landsman June 97
Added /INFO to final MESSAGE W. Landsman July 1997
12/4/97 jkf/acc - added TrueColor optional keyword.
Added /NoClose keyword, trim Equinox format W. Landsman 9-Jul-1998
Don't display coordinate labels if no astrometry, more flexible
formatting of exposure time W. Landsman 30-Aug-1998
BottomDW and NColorsDW added. R. S. Hill, 1-Mar-1999
Apply func tab to color bar if not colorps. RSH, 21 Mar 2000
Fix problem with /NOCLOSE and unequal X,Y sizes W. Landsman Feb 2001
Use TVRD(True=3) if /TRUECOLOR set W. Landsman November 2001
More synonyms, check for header supplied W. Landsman November 2007
(See astrolib/pro/tvlaser.pro)
TVLIST
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NAME:
TVLIST
PURPOSE:
Cursor controlled listing of image pixel values in a window.
CALLING SEQUENCE:
TVLIST, [image, dx, dy, TEXTOUT=, OFFSET= , ZOOM= ]
OPTIONAL INPUTS:
IMAGE - Array containing the image currently displayed on the screen.
If omitted, the byte pixel intensities are read from the TV
If the array does not start at position (0,0) on the window then
the OFFSET keyword should be supplied.
DX -Integer scalar giving the number of pixels in the X direction
to be displayed. If omitted then DX = 18 for byte images, and
DX = 14 for integer images. TVLIST will display REAL data
with more significant figures if more room is availble to
print.
DY - Same as DX, but in Y direction. If omitted, then DY = DX
OPTIONAL INPUT KEYWORDS:
OFFSET - 2 element vector giving the location of the image pixel (0,0)
on the window display. OFFSET can be positive (e.g if the
image is centered in a larger window) or negative (e.g. if the
only the central region of an image much larger than the window
is being displayed.
Default value is [0,0], or no offset.
ZOOM - Scalar specifying the magnification of the window with respect
to the image variable. Use, for example, if image has been
REBINed before display.
TEXTOUT - Optional keyword that determines output device.
The following dev/file is opened for output.
textout=1 TERMINAL using /more option (default)
textout=2 TERMINAL without /more option
textout=3 .prt
textout=4 laser.tmp
textout=5 user must open file
textout=7 Append to an existing .prt file if it
exists
textout = filename (default extension of .prt)
If TEXTOUT > 3 or set to a filename, then TVLIST will prompt for a
brief description to be included in the output file
OUTPUTS:
None.
PROCEDURE:
Program prompts user to place cursor on region of interest in
image display. Corresponding region of image is then displayed at
the terminal. A compression factor between the image array and the
displayed image is determined using the ratio of image sizes. If
necessary, TVLIST will divide all pixel values in a REAL*4 image by a
(displayed) factor of 10^n (n=1,2,3...) to make a pretty format.
SYSTEM VARIABLE:
The nonstandard system variable !TEXTOUT is used as an alternative to
the keyword TEXTOUT. The procedure ASTROLIB can be used to define
!TEXTOUT (and !TEXTUNIT) if necessary.
RESTRICTIONS:
TVLIST may not be able to correctly format all pixel values if the
dynamic range near the cursor position is very large.
For the cursor to work under Mac OSX the "Click-through Inactive
Windows" setting the in X11:Preferences:Window needs to be enabled.
PROCEDURES CALLED:
IMLIST, UNZOOM_XY
REVISION HISTORY:
Written by rhc, SASC Tech, 3/14/86.
Added textout keyword option, J. Isensee, July, 1990
Check for readable pixels W. Landsman May 1992
Use integer format statement from F_FORMAT W. Landsman Feb 1994
Added OFFSET, ZOOM keywords W. Landsman Mar 1996
More intelligent formatting of longword, call TEXTOPEN with /STDOUT
W. Landsman April, 1996
Added check for valid dx value W. Landsman Mar 1997
Converted to IDL V5.0 W. Landsman September 1997
Major rewrite to call IMLIST, recognize new integer data types
W. Landsman Jan 2000
Remove all calls to !TEXTUNIT W. Landsman Sep 2000
Always call UNZOOM_XY for MOUSSE compatibility W. Landsman Sep. 2004
(See astrolib/pro/tvlist.pro)
T_APER
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NAME:
T_APER
PURPOSE:
Driver procedure (for APER) to compute concentric aperture photometry.
EXPLANATION:
Data is read from and written to disk FITS ASCII tables.
Part of the IDL-DAOPHOT photometry sequence
CALLING SEQUENCE:
T_APER, image, fitsfile, [ apr, skyrad, badpix, PRINT=, NEWTABLE=,
/EXACT, /SILENT, SETSKYVAL = ]
INPUTS:
IMAGE - input data array
FITSFILE - disk FITS ASCII table name (from T_FIND). Must contain
the keywords 'X' and 'Y' giving the centroid of the source
positions in FORTRAN (first pixel is 1) convention. An
extension of .fit is assumed if not supplied.
OPTIONAL INPUTS:
User will be prompted for the following parameters if not supplied.
APR - Vector of up to 12 REAL photometry aperture radii.
SKYRAD - Two element vector giving the inner and outer radii
to be used for the sky annulus
BADPIX - Two element vector giving the minimum and maximum
value of a good pixel (Default [-32765,32767])
OPTIONAL KEYWORDS INPUTS:
/EXACT - If this keyword is set, then intersection of the circular
aperture is computed exactly (and slowly) rather than using
an approximation. See APER for more info.
/PRINT - if set and non-zero then NSTAR will also write its results to
a file aper.prt. One can specify a different output file
name by setting PRINT = 'filename'.
/SILENT - If this keyword is set and non-zero, then APER will not
display photometry results at the screen, and the results
will be automatically incorporated in the FITS table without
prompting the user
NEWTABLE - Name of output disk FITS ASCII table, scalar string.
If not supplied, then the input FITSFILE will be updated with
the aperture photometry results.
SETSKYVAL - Use this keyword to force the sky to a specified value
rather than have APER compute a sky value. SETSKYVAL
can either be a scalar specifying the sky value to use for
all sources, or a 3 element vector specifying the sky value,
the sigma of the sky value, and the number of elements used
to compute a sky value. The 3 element form of SETSKYVAL
is needed for accurate error budgeting.
PROMPTS:
T_APER requires the number of photons per analog digital unit
(PHPADU), so that it can compute Poisson noise statistics to assign
photometry errors. It first tries to find the PHPADU keyword in the
original image header, and if not found will look for the GAIN,
CCDGAIN and finally ATODGAIN keywords. If still not found, T_APER
will prompt the user for this value.
PROCEDURES:
APER, FTADDCOL, FTGET(), FTINFO, FTPUT, READFITS(), SXADDPAR,
SXPAR(), WRITEFITS
REVISON HISTORY:
Written W. Landsman ST Systems Co. May 1988
Store results as flux or magnitude August 1988
Added SILENT keyword W. Landsman Sep. 1991
Changed ERR SKY to ERR_SKY W. Landsman March 1996
Replace TEXTOUT keyword with PRINT keyword W. Landsman May 1996
Check CCDGAIN or ATODGAIN keywords to find phpadu W. Landsman May 1997
Converted to IDL V5.0 W. Landsman September 1997
Updated for new FTINFO calling sequence W. Landsman May 2000
Added /EXACT keyword W. Landsman June 2000
(See astrolib/pro/t_aper.pro)
T_FIND
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NAME:
T_FIND
PURPOSE:
Driver procedure (for FIND) to locate stars in an image.
EXPLANATION:
Finds positive brightness perturbations (i.e stars) in a
2 dimensional image. Output is to a FITS ASCII table.
CALLING SEQUENCE:
T_FIND, image, im_hdr, [ fitsfile, hmin, fwhm, sharplim, roundlim,
PRINT = , /SILENT ]
INPUTS:
image - 2 dimensional image array (integer or real) for which one
wishes to identify the stars present
im_hdr - FITS header associated with image array
OPTIONAL INPUTS:
T_FIND will prompt for these parameters if not supplied
fitsfile - scalar string specifying the name of the output FITS ASCII
table file
fwhm - FWHM to be used in the convolving filter
hmin - Threshold intensity for a point source - should generally
be 3 or 4 sigma above background level
sharplim - 2 element vector giving low and high Limit for
sharpness statistic (Default: [0.2,1.0] )
roundlim - 2 element vector giving low and high Limit for
roundness statistic (Default: [-1.0,1.0] )
OPTIONAL INPUT KEYWORDS:
/PRINT - if set and non-zero then NSTAR will also write its results to
a file find.prt. One can specify the output file name by
setting PRINT = 'filename'.
/SILENT - If this keyword is set and non-zero, then FIND will work
silently, and not display each star found
OUTPUTS:
None
PROCEDURES CALLED:
CHECK_FITS, FDECOMP, FIND, FTADDCOL, FTCREATE, SXADDHIST, SXADDPAR,
SXDELPAR, SXPAR(), WRITEFITS
REVISION HISTORY:
Written W. Landsman, STX May, 1988
Added phpadu, J. Hill, STX, October, 1990
New calling syntax output to disk FITS table, W. Landsman May 1996
Work with more than 32767 stars W. Landsman August 1997
Converted to IDL V5.0 W. Landsman September 1997
Remove obsolete !ERR system variable W. Landsman May 2000
(See astrolib/pro/t_find.pro)
T_GETPSF
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NAME:
T_GETPSF
PURPOSE:
Driver procedure (for GETPSF) to generate a PSF from isolate stars.
EXPLANATION:
Generates a point-spread function from one or more isolated stars.
List of stars is read from the FITS ASCII table output of T_APER.
PSF is represented as a sum of a Gaussian plus residuals.
Ouput residuals are written to a FITS image file.
CALLING SEQUENCE:
T_GETPSF, image, fitsfile, [ idpsf, psfrad, fitrad, psfname,
/DEBUG, NEWTABLE =]
INPUTS:
IMAGE - image array
FITSFILE - scalar string giving name of disk FITS ASCII table. Must
contain the keywords 'X','Y' (from T_FIND) and 'AP1_MAG','SKY'
(from T_APER).
OPTIONAL INPUTS:
IDPSF - vector of stellar ID indices indicating which stars are to be
used to create the PSF. Not that the PSF star should be
specified *not* by its STAR_ID value, but rather by the its
row number (starting with 0) in the FITS table
PSFRAD - the radius for which the PSF will be defined
FITRAD - fitting radius, always smaller than PSFRAD
PSFNAME - name of FITS image file to contain PSF residuals,
scalar string
GETPSF will prompt for all the above values if not supplied.
OPTIONAL KEYWORD INPUT
NEWTABLE - scalar string specifying the name of the output FITS ASCII
table. If not supplied, then the input table is updated with
the keyword PSF_CODE, specifying which stars were used for the
PSF.
DEBUG - if this keyword is set and non-zero, then the result of each
fitting iteration will be displayed.
PROMPTS:
T_GETPSF will prompt for the readout noise (in data numbers), and
the gain (in photons or electrons per data number) so that pixels can
be weighted during the PSF fit. To avoid the prompt, add the
keywords RONOIS and PHPADU to the FITS ASCII table header.
PROCEDURES USED:
FTADDCOL, FTGET(), FTPUT, GETPSF, READFITS(), SXADDHIST, SXADDPAR,
SXPAR(), WRITEFITS, ZPARCHECK
REVISION HISTORY:
Written W. Landsman STX May, 1988
Update PSF_CODE to indicate PSF stars in order used, W. Landsman Mar 96
I/O to FITS ASCII disk files W. Landsman May 96
Converted to IDL V5.0 W. Landsman September 1997
Update for new FTINFO call W. Landsman May 2000
(See astrolib/pro/t_getpsf.pro)
T_GROUP
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NAME:
T_GROUP
PURPOSE:
Driver procedure (for GROUP) to place stars in non-overlapping groups.
EXPLANATION:
This procedure is part of the DAOPHOT sequence that places star
positions with non-overlapping PSFs into distinct groups
Input and output are to FITS ASCII tables
CALLING SEQUENCE:
T_GROUP, fitsfile, [ rmax, XPAR = , YPAR = , NEWTABLE = ]
INPUTS:
FITSFILE - Name of disk FITS ASCII table containing the X,Y positions
in FITS (FORTRAN) convention (first pixel is 1,1)
OPTIONAL INPUTS:
rmax - maximum allowable distance between stars in a single group
OPTIONAL INPUT KEYWORDS:
XPAR, YPAR - scalar strings giving the field name in the output table
containing the X and Y coordinates. If not supplied,
then the fields 'X' and 'Y' are read.
NEWTABLE - scalar giving name of output disk FITS ASCII table. If not
supplied,
PROCEDURES:
FTADDCOL, FTGET(), FTINFO, FTPUT, GROUP, READFITS(), SXADDHIST,
SXADDHIST, WRITEFITS
REVISION HISTORY:
Written, W. Landsman STX Co. May, 1996
Converted to IDL V5.0 W. Landsman September 1997
Updated for new FTINFO call W. Landsman May 2000
(See astrolib/pro/t_group.pro)
T_NSTAR
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NAME:
T_NSTAR
PURPOSE:
Driver procedure (for NSTAR) for simultaneous PSF fitting.
EXPLANATION:
Input and output are to disk FITS ASCII tables.
CALLING SEQUENCE:
T_NSTAR, image, fitsfile, [psfname, groupsel, /SILENT, /PRINT
NEWTABLE = , /VARSKY ]
INPUTS:
IMAGE - 2-d image array
FITSFILE - scalar string giving name of disk FITS ASCII table. Must
contain the keywords 'X','Y' (from T_FIND) 'AP1_MAG','SKY'
(from T_APER) and 'GROUP_ID' (from T_GROUP). This table
will be updated with the results of T_NSTAR, unless the
keyword NEWTABLE is supplied.
OPTIONAL INPUTS:
PSFNAME - Name of the FITS file created by T_GETPSF containing
PSF residuals, scalar string
GROUPSEL - Scalar or vector listing the groups to process. For
example, to process stars in groups 2 and 5 set
GROUPSEL = [2,5]. If omitted, or set equal to -1,
then NSTAR will process all groups.
OPTIONAL KEYWORD INPUTS:
VARSKY - If this keyword is set and non-zero, then the mean sky level
in each group of stars, will be fit along with the brightness
and positions.
/SILENT - if set and non-zero, then NSTAR will not display its results
at the terminal
/PRINT - if set and non-zero then NSTAR will also write its results to
a file NSTAR.PRT. One can specify the output file name by
setting PRINT = 'filename'.
NEWTABLE - Name of output disk FITS ASCII table to contain the results
of NSTAR. If not supplied, then the input FITSFILE will be
updated.
DEBUG - if this keyword is set and non-zero, then the result of each
fitting iteration will be displayed.
PROCEDURES CALLED:
FTADDCAL, FTINFO, FTGET(), FTPUT, NSTAR, SXADDHIST,
SXADDPAR, SXPAR(), READFITS(), WRITEFITS
REVISION HISTORY:
Written W. Landsman STX Co. May, 1988
Check for CCDGAIN, ATODGAIN keywords to get PHPADU W. Landsman May 1997
Fixed typo preventing compilation, groupsel parameter W.L. July 1997
Converted to IDL V5.0 W. Landsman September 1997
Update for new FTINFO call W. Landsman May 2000
(See astrolib/pro/t_nstar.pro)
T_SUBSTAR
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NAME:
T_SUBSTAR
PURPOSE:
Driver procedure (for SUBSTAR) to subtract scaled PSF values
EXPLANATION:
Computes residuals of the PSF fitting program
CALLING SEQUENCE:
T_SUBSTAR, image, fitsfile, id,[ psfname, /VERBOSE, /NOPSF ]
INPUT-OUTPUT:
IMAGE - On input, IMAGE is the original image array. A scaled
PSF will be subtracted from IMAGE at specified star positions.
Make a copy of IMAGE before calling SUBSTAR, if you want to
keep a copy of the unsubtracted image array
INPUTS:
FITSFILE - scalar string giving the name of the disk FITS ASCII
produced as an output from T_NSTAR.
OPTIONAL INPUTS:
ID - Index vector indicating which stars are to be subtracted. If
omitted, (or set equal to -1), then stars will be subtracted
at all positions specified by the X and Y vectors.
(IDL convention - zero-based subscripts)
PSFNAME - Name of the FITS file containing the PSF residuals, as
generated by GETPSF. SUBSTAR will prompt for this parameter
if not supplied.
OPTIONAL INPUT KEYWORD:
/VERBOSE - If this keyword is set and non-zero, then the value of each
star number will be displayed as it is processed.
/NOPSF - if this keyword is set and non-zero, then all stars will be
be subtracted *except* those used to determine the PSF.
An improved PSF can then be derived from the subtracted image.
If NOPSF is supplied, then the ID parameter is ignored
NOTES:
T_SUBSTAR does not modify the input FITS table.
PROCEDURES USED:
FTGET(), FTINFO, READFITS(), REMOVE, SUBSTAR
REVISION HISTORY:
Written, R. Hill, ST Sys. Corp., 22 August 1991
Added NOPSF keyword W. Landsman March, 1996
Use FITS format for PSF resduals July, 1997
Converted to IDL V5.0 W. Landsman September 1997
Call FTINFO first to improve efficiency W. Landsman May 2000
(See astrolib/pro/t_substar.pro)
UNZOOM_XY
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NAME:
UNZOOM_XY
PURPOSE:
Converts X, Y position on the image display to the the X,Y position
on the corresponding image array. (These positions are identical
only for an unroamed, unzoomed image with with pixel (0,0) of the
image placed at position (0,0) on the TV.)
CALLING SEQUENCE:
UNZoom_XY, Xtv,Ytv,Xim,Yim, [ OFFSET =, ZOOM = ]
INPUTS:
XTV - Scalar or vector giving X position(s) as read on the image
display (e.g. with CURSOR,XTV,YTV,/DEVICE)
XTV - Scalar or vector giving Y position(s) on the image display.
If only 2 parameters are supplied then XTV and YTV will be modfied
on output to contain the image array coordinates.
OPTIONAL KEYWORD INPUT:
OFFSET - 2 element vector giving the location of the image pixel (0,0)
on the window display. OFFSET can be positive (e.g if the
image is centered in a larger window) or negative (e.g. if the
only the central region of an image much larger than the window
is being displayed.
Default value is [0,0], or no offset.
OUTPUTS:
XIM,YIM - X and Y coordinates of the image corresponding to the
cursor position on the TV display.
COMMON BLOCKS:
If present, ZOOM_XY will use the TV and IMAGE common blocks which are
defined in the MOUSSE software system (see
http://archive.stsci.edu/uit/analysis.html) If the user is not using
the MOUSSE software (which keeps track of the offset and zoom in each
window) then the common blocks are ignored.
NOTES:
The integer value of a pixel is assumed to refer to the *center*
of a pixel.
REVISON HISTORY:
Adapted from MOUSSE procedure W. Landsman March 1996
Converted to IDL V5.0 W. Landsman September 1997
Proper handling of offset option S. Ott/W. Landsman May 2000
Put back common blocks for MOUSSE compatibility September 2004
(See astrolib/pro/unzoom_xy.pro)
UPDATE_DISTORT
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NAME:
UPDATE_DISTORT
PURPOSE:
Update SIP nonlinear distortion coefficients for a linear transformation
EXPLANATION:
The SIP coefficients can account for nonlinearities in the astrometry
of an astronomical image. When the image is compressed or expanded
these coefficients must be adjusted in a nonlinear way.
CALLING SEQUENCE:
UPDATE_DISTORT, distort, xcoeff, ycoeff
INPUT/OUTPUT:
distort - structure giving SIP coefficients. See extast.pro for
description of the SIP distortion structure
xcoeff - 2 element numeric vector describing the linear transformation
xp = xcoeff[0]*x + xcoeff[1]
xcoeff - 2 element numeric vector describing the linear transformation
yp = ycoeff[0]*x + ycoeff[1]
METHOD:
The procedure TRANSFORM_COEFF is used to determine how the
coefficients change under the linear transformation.
See example of usage in hrebin.pro
REVISION HISTORY:
Written, December 2007 W. Landsman
(See astrolib/pro/update_distort.pro)
UVBYBETA
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NAME:
UVBYBETA
PURPOSE:
Derive dereddened colors, metallicity, and Teff from Stromgren colors.
EXPLANATION:
Adapted from FORTRAN routine of same name published by T.T. Moon,
Communications of University of London Observatory, No. 78. Parameters
can either be input interactively (with /PROMPT keyword) or supplied
directly.
CALLING SEQUENCE:
uvbybeta, /PROMPT ;Prompt for all parameters
uvbybeta,by,m1,c1,Hbeta,n ;Supply inputs, print outputs
uvbybeta, by, m1, c1, Hbeta, n, Te, Mv, Eby, delm0, radius,
[ TEXTOUT=, Eby_in =, Name = ]
INPUTS:
by - Stromgren b-y color, scalar or vector
m1 - Stromgren line-blanketing parameter, scalar or vector
c1 - Stromgren Balmer discontinuity parameter, scalar or vector
Hbeta - H-beta line strength index. Set Hbeta to 0 if it is not
known, and UVBYBETA will estimate a value based on by, m1,and c1.
Hbeta is not used for stars in group 8.
n - Integer (1-8), scalar or vector, giving approximate stellar
classification
(1) B0 - A0, classes III - V, 2.59 < Hbeta < 2.88,-0.20 < c0 < 1.00
(2) B0 - A0, class Ia , 2.52 < Hbeta < 2.59,-0.15 < c0 < 0.40
(3) B0 - A0, class Ib , 2.56 < Hbeta < 2.61,-0.10 < c0 < 0.50
(4) B0 - A0, class II , 2.58 < Hbeta < 2.63,-0.10 < c0 < 0.10
(5) A0 - A3, classes III - V, 2.87 < Hbeta < 2.93,-0.01 < (b-y)o< 0.06
(6) A3 - F0, classes III - V, 2.72 < Hbeta < 2.88, 0.05 < (b-y)o< 0.22
(7) F1 - G2, classes III - V, 2.60 < Hbeta < 2.72, 0.22 < (b-y)o< 0.39
(8) G2 - M2, classes IV _ V, 0.20 < m0 < 0.76, 0.39 < (b-y)o< 1.00
OPTIONAL INPUT KEYWORD:
Eby_in - numeric scalar specifying E(b-y) color to use. If not
supplied, then E(b-y) will be estimated from the Stromgren colors
NAME - scalar or vector string giving name(s) of star(s). Used only
when writing to disk for identification purposes.
/PROMPT - if set, then uvbybeta.pro will prompt for Stromgren indicies
interactively
TEXTOUT - Used to determine output device. If not present, the
value of the !TEXTOUT system variable is used (see TEXTOPEN)
textout=1 Terminal with /MORE (if a tty)
textout=2 Terminal without /MORE
textout=3 uvbybeta.prt (output file)
textout=4 Laser Printer
textout=5 User must open file
textout=7 Append to existing uvbybeta.prt file
textout = filename (default extension of .prt)
/PRINT - if set, then force display output information to the device
specified by !TEXTOUT. By default, UVBYBETA does not display
information if output variables are supplied (and TEXTOUT is
not set).
OPTIONAL OUTPUTS:
Te - approximate effective temperature
MV - absolute visible magnitude
Eby - Color excess E(b-y)
delm0 - metallicity index, delta m0, (may not be calculable for early
B stars).
radius - Stellar radius (R/R(solar))
EXAMPLE:
Suppose 5 stars have the following Stromgren parameters
by = [-0.001 ,0.403, 0.244, 0.216, 0.394 ]
m1 = [0.105, -0.074, -0.053, 0.167, 0.186 ]
c1 = [0.647, 0.215, 0.051, 0.785, 0.362]
hbeta = [2.75, 2.552, 2.568, 2.743, 0 ]
nn = [1,2,3,7,8] ;Processing group number
Determine stellar parameters and write to a file uvbybeta.prt
IDL> uvbybeta, by,m1,c1,hbeta, nn, t=3
==> E(b-y) = 0.050 0.414 0.283 0.023 -0.025
Teff = 13060 14030 18420 7250 5760
M_V = -0.27 -6.91 -5.94 2.23 3.94
radius= 2.71 73.51 39.84 2.02 1.53
SYSTEM VARIABLES:
The non-standard system variables !TEXTOUT and !TEXTUNIT will be
automatically defined if they are not already present.
DEFSYSV,'!TEXTOUT',1
DEFSYSV,'!TEXTUNIT',0
NOTES:
(1) **This procedure underwent a major revision in January 2002
and the new calling sequence may not be compatible with the old** (NAME
is now a keyword rather than a parameter.)
(2) Napiwotzki et al. (1993, A&A, 268, 653) have written a FORTRAN
program that updates some of the Moon (1985) calibrations. These
updates are *not* included in this IDL procedure.
PROCEDURES USED:
DEREDD, TEXTOPEN, TEXTCLOSE
REVISION HISTORY:
W. Landsman IDL coding February, 1988
Keyword textout added, J. Isensee, July, 1990
Made some constants floating point. W. Landsman April, 1994
Converted to IDL V5.0 W. Landsman September 1997
Added Eby_in, /PROMPT keywords, make NAME a keyword and not a parameter
W. Landsman January 2002
(See astrolib/pro/uvbybeta.pro)
VACTOAIR
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NAME:
VACTOAIR
PURPOSE:
Convert vacuum wavelengths to air wavelengths
EXPLANATION:
Corrects for the index of refraction of air under standard conditions.
Wavelength values below 2000 A will not be altered. Accurate to
about 10 m/s.
CALLING SEQUENCE:
VACTOAIR, WAVE_VAC, [WAVE_AIR]
INPUT/OUTPUT:
WAVE_VAC - Vacuum Wavelength in Angstroms, scalar or vector
If the second parameter is not supplied, then this will be
updated on output to contain double precision air wavelengths.
OPTIONAL OUTPUT:
WAVE_AIR - Air wavelength in Angstroms, same number of elements as
WAVE_VAC, double precision
EXAMPLE:
If the vacuum wavelength is W = 2000, then
IDL> VACTOAIR, W
yields an air wavelength of W = 1999.353 Angstroms
METHOD:
Formula from Ciddor 1996 Applied Optics , 35, 1566
REVISION HISTORY
Written, D. Lindler 1982
Documentation W. Landsman Feb. 1989
Use Ciddor (1996) formula for better accuracy in the infrared
Added optional output vector, W Landsman Mar 2011
(See astrolib/pro/vactoair.pro)
VALID_NUM()
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NAME:
VALID_NUM()
PURPOSE:
Check if a string is a valid number representation.
EXPLANATION:
The input string is parsed for characters that may possibly
form a valid number. It is more robust than simply checking
for an IDL conversion error because that allows strings such
as '22.3qwert' to be returned as the valid number 22.3
This function had a major rewrite in August 2008 to use STREGEX
and allow vector input. It should be backwards compatible.
CALLING SEQUENCE:
IDL> status = valid_num(string [,value] [,/integer])
INPUTS:
string - the string to be tested, scalar or array
RETURNS
status - byte scalar or array, same size as the input string
set to 1 where the string is a valid number, 0 for invalid
OPTIONAL OUTPUT:
value - The value the string decodes to, same size as input string.
This will be returned as a double precision number unless
/INTEGER is present, in which case a long integer is returned.
OPTIONAL INPUT KEYWORD:
/INTEGER - if present code checks specifically for an integer.
EXAMPLES:
(1) IDL> print,valid_num(3.2,/integer)
--> 0 ;Since 3.2 is not an integer
(2) IDL> str =['-0.03','2.3g', '3.2e12']
IDL> test = valid_num(str,val)
test = [1,0,1] & val = [-0.030000000 ,NaN ,3.2000000e+12]
REVISION HISTORY:
Version 1, C D Pike, RAL, 24-May-93
Version 2, William Thompson, GSFC, 14 October 1994
Added optional output parameter VALUE to allow
VALID_NUM to replace STRNUMBER in FITS routines.
Version 3 Wayne Landsman rewrite to use STREGEX, vectorize
Version 4 W.L. (fix from C. Markwardt) Better Stregex expression,
was missing numbers like '134.' before Jan 1 2010
(See astrolib/pro/valid_num.pro)
VECT
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NAME:
VECT
PURPOSE:
Print a set of numbers as a string with delimiters included
EXPLANATION:
This function returns the given vector in parenthesized coordinates
as in the form (X,Y). No limit on the number of dimensions. Also
note that the vector does not need to be numbers. It may also be a
string vector. e.g. ['X','Y']
CALLING SEQEUNCE:
tmp = VECT( vctr, [ form, FORMAT = , DELIM = ] )
INPUT:
VCTR The vector to be displayed e.g. [56,44]
OPTIONAL KEYWORD INPUT:
FORMAT This KEYWORD allows the specification of a format for the
elements. e.g.: VECT([2,3],format='(f7.1)') gives '(2.0,3.0)'
DELIM This KEYWORD specifies the delimeter. The default is ',' but
other useful examples might be ', ' or ':'
OPTIONAL INPUT
FORM This parameter may be used instead of the keyword FORMAT
OUTPUT:
tmp A returned string of the parenthesized vector
Other Procedures/Functions Called:
STRN
HISTORY:
03-JUL-90 Version 1 written by Eric W. Deutsch
24-AUG-91 Format='' keyword added (E. Deutsch)
29-AUG-91 FORM parameter added (E. Deutsch)
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/vect.pro)
VSYM
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NAME:
VSYM
PURPOSE:
Create "Mongo"-like polygonal plot symbols
EXPLANATION:
This procedure generates a subset of Mongo-like plot symbols.
The symbols are the rotationally symmetric ones that have
a specified number of vertices and are either open or filled.
(The half-filled symbols are not included.) After defining the
plot symbol with VSYM, make the call to PLOT (or PLOTS or OPLOT) with
PSYM=8.
CATEGORY:
Graphics
CALLING SEQUENCE:
VSYM, Nvert
INPUT POSITIONAL PARAMETERS:
Nvert: Number of vertices in plot symbol. Maximum value
used is 24.
INPUT KEYWORD PARAMETERS:
STAR: Set this flag to get a star. E.g.,
vsym, 5,/star gets you a pentagram.
SKELETON: Set this flag to get an asterisk-like symbol, where
the center is connected to each vertex. E.g.,
vsym, 4, /skel gets you an X.
POLYGON: Set this flag to get a regular polygon. This is
the default symbol type.
FILL: Set this flag to get filled symbol. Default=open
ROT: Rotation of symbol about center, in degrees.
E.g., vsym, 4, rot=45 gets you a diamond, whereas
vsym, 4 gets you a square.
THICK: Line thickness of symbol. Default=!P.thick
MODIFICATION HISTORY:
Written by: R. S. Hill, RITSS, 2 Oct 98
(See astrolib/pro/vsym.pro)
WCSSPH2XY
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NAME:
WCSSPH2XY
PURPOSE:
Convert spherical coordinates to x and y (map) angular coordinates
EXPLANATION:
Convert spherical (longitude and latitude -- sky) coordinates to x
and y (map) angular coordinates. This procedure is the inverse of
WCSXY2SPH. See WCS_DEMO for example of use.
This is a lower level procedure -- given a FITS header, the user will
usually use ADXY which will then call WCSSPH2XY with the appropriate
parameters.
CATEGORY:
Mapping and Auxiliary FITS Routine
CALLING SEQUENCE:
wcssph2xy, longitude, latitude, x, y, [ map_type , CTYPE = ,
FACE =,PV2= , CRVAL = , CRXY = , LONGPOLE = ,
LATPOLE = , NORTH_OFFSET =, SOUTH_OFFSET =, BADINDEX =]
INPUT PARAMETERS:
longitude - longitude of data, scalar or vector, in degrees
latitude - latitude of data, same number of elements as longitude,
in degrees
map_type - optional positional parameter, numeric scalar (0-26)
corresponding to a particular map projection. This is not a
FITS standard, it is simply put in to allow function similar
to that of less general map projection procedures (eg AITOFF).
The following list gives the map projection types and their
respective numbers.
FITS Number Name Comments
code code
---- ------ ----------------------- -----------------------------------
DEF 0 Default = Cartesian
AZP 1 Zenithal perspective PV2_1 required
TAN 2 Gnomic AZP w/ mu = 0
SIN 3 Orthographic PV2_1,PV2_2 optional
STG 4 Stereographic AZP w/ mu = 1
ARC 5 Zenithal Equidistant
ZPN 6 Zenithal polynomial PV2_0, PV2_1....PV2_20 possible
ZEA 7 Zenithal equal area
AIR 8 Airy PV2_1 required
CYP 9 Cylindrical perspective PV2_1 and PV2_2 required
CAR 10 Cartesian
MER 11 Mercator
CEA 12 Cylindrical equal area PV2_1 required
COP 13 Conical perspective PV2_1 and PV2_2 required
COD 14 Conical equidistant PV2_1 and PV2_2 required
COE 15 Conical equal area PV2_1 and PV2_2 required
COO 16 Conical orthomorphic PV2_1 and PV2_2 required
BON 17 Bonne's equal area PV2_1 required
PCO 18 Polyconic
SFL 19 Sanson-Flamsteed
PAR 20 Parabolic
AIT 21 Hammer-Aitoff
MOL 22 Mollweide
CSC 23 Cobe Quadrilateralized convergence of inverse is poor
Spherical Cube
QSC 24 Quadrilateralized
Spherical Cube
TSC 25 Tangential Spherical Cube
SZP 26 Slant Zenithal Projection PV2_1,PV2_2, PV2_3 optional
HPX 27 HealPix
HCT 28 HealCart (Cartesian approximation of Healpix)
OPTIONAL INPUT KEYWORD PARAMETERS:
CTYPE - One, two, or three element vector containing 8 character
strings corresponding to the CTYPE1, CTYPE2, and CTYPE3
FITS keywords:
CTYPE[0] - first four characters specify standard system
('RA--','GLON' or 'ELON' for right ascension, Galactic
longitude or ecliptic longitude respectively), second four
letters specify the type of map projection (eg '-AIT' for
Aitoff projection)
CTYPE[1] - first four characters specify standard system
('DEC-','GLAT' or 'ELAT' for declination, galactic latitude
or ecliptic latitude respectively; these must match
the appropriate system of ctype1), second four letters of
ctype2 must match second four letters of ctype1.
CTYPE[2] - if present must be the 8 character string,'CUBEFACE',
only used for spherical cube projections to identify an axis
as containing the face on which each x and y pair of
coordinates lie.
PV2 - Vector of projection parameter associated with latitude axis
PV2 will have up to 21 elements for the ZPN projection, up to 3
for the SIN projection and no more than 2 for any other
projection. The first element corresponds to PV2_1, the
second to PV2_2, etc.
CRVAL - 2 element vector containing standard system coordinates (the
longitude and latitude) of the reference point
CRXY - 2 element vector giving the x and y coordinates of the
reference point, if this is not set the offset is [0,0]
This is not a FITS standard -- it is similar to CRPIX but in
angular X,Y coordinates (degrees) rather than pixel coordinates
LATPOLE - native latitude of the standard system's North Pole
LONGPOLE - native longitude of standard system's North Pole, default
is 180 degrees for Zenithal systems
NORTH_OFFSET - offset (radians) added to input points near north pole.
SOUTH_OFFSET - offset (radians) added to input points near south pole.
BADINDEX - vector, list of transformed points too close to poles.
OUTPUT PARAMETERS:
x - x coordinate of data, same number of elements as longitude, in
degrees; if CRXY is set, then x will be returned offset by
crxy(0). NOTE: x in all map projections increases to the
left, not the right.
y - y coordinate of data, same number of elements as longitude, in
degrees; if CRXY is set, y will be returned offset by crxy[1]
bad - vector returning index to transformed points close to pole.
OPTIONAL OUTPUT KEYWORD PARAMETERS:
FACE - a output variable used for spherical cube projections to
designate the face of the cube on which the x and y
coordinates lie. Will contain the same number of elements as
X and Y. Must contain at least 1 arbitrary element on input
If FACE is NOT defined on input, it is assumed that the
spherical cube projection is laid out over the whole sky
in the "sideways T" configuration.
NOTES:
The conventions followed here are described in more detail in
"Representations of Celestial Coordinates in FITS" by Calabretta
and Greisen (2002, A&A, 395, 1077; also see
http://fits.gsfc.nasa.gov/fits_wcs.html). The general
scheme outlined in that article is to first use WCS_ROTATE to convert
coordinates in one of three standard systems (celestial, galactic,
or ecliptic) into a "native system" of latitude and longitude. The
latitude and longitude are then converted into x and y coordinates
which depend on the map projection which is performed. The rotation
from standard to native coordinates can be skipped if one so desires.
This procedure necessitates two basic sections. The first converts
"standard" coordinates to "native" coordinates while the second converts
"native" coordinates to x and y coordinates. The first section is
simply a call to WCS_ROTATE, while the second contains the guts of
the code in which all of the map projection is done. This procedure
can be called in a form similar to AITOFF, EQPOLE, or QDCB by calling
wcssph2xy with a fifth parameter specifying the map projection by
number and by not using any of the keywords related to the map
projection type (e.g. CTYPE).
PROCEDURE:
The first task of the procedure is to do general error-checking to
make sure the procedure was called correctly and none of the
parameters or keywords conflict. This is particularly important
because the procedure can be called in two ways (either using
FITS-type keywords or using a number corresponding to a map projection
type). All variables are converted into double precision values and
angular measurements are converted from degrees into radians.
If necessary, longitude values are converted into the range -pi to pi.
Any latitude points close to the of the poles are mapped to a specific
latitude of from the pole so that the map transformations become
completely invertible. The magnitude of this correction is given by
the keywords NORTH_OFFSET and SOUTH_OFFSET and a list of affected
points is optionally returned in the "badindex" output parameter.
The next task of the procedure is to convert the "standard"
coordinates to "native" coordinates by rotating the coordinate system.
This rotation is performed by the procedure WCS_ROTATE and is governed
by the keywords CRVAL and LONGPOLE. The final task of the WCSSPH2XY
is to take "native" latitude and longitude coordinates and convert
them into x and y coordinates. Any map specific error-checking is
done at this time. All of the equations were obtained from
"Representations of Celestial Coordinates in FITS" and cases needing
special attention are handled appropriately (see the comments with
individual map projections for more information on special cases).
Note that a further transformation (using the CD matrix) is required
to convert the (x,y) coordinates to pixel coordinates.
COMMON BLOCKS:
none
PROCEDURES CALLED:
WCS_ROTATE
AUTHOR:
Rick Balsano
MODIFICATIONS/REVISION LEVEL:
1.1 8/31/93
2.3 9/15/93 W. Landsman (HSTX) Update quad cube coords, vectorize
keywords
2.4 12/29/93 I. Freedman (HSTX) Eliminated LU decomposition
2.5 1/5/93 I. Freedman (HSTX) Offset keywords / bad point index
2.6 Dec 94 Compute pole for transformations where the reference
pixel is at the native origin W. Landsman (HSTX)
2.7 May 95 Change internal variable BETA for V4.0 compatibility
2.8 June 95 Change loop indices from integer to long
2.9 3/18/96 Change FACE usage for cube projections to match WCSLIB
C/FORTRAN software library.
2.10 02/18/99 Fixed implementation of ARC algorithm
2.11 June 2003 Update conic projections, add LATPOLE keyword
2.12 Aug 2003, N.Rich - Fix pre-V5.5 bug from previous update
2.13 Sep 2003, W. Landsman CTYPE keywords need not be 8 characters
2.14 Jan 2004, W. Landsman don't modify scalars, fix PARabolic code
2.15 Feb 2004, W. Landsman Fix AZP and AIR algorithms
3.0 May 2004 W. Landsman Support extended SIN (=NCP), slant zenithal
(SZP), and zenithal polynomail (ZPN) projections, use
PV2 keyword vector instead of PROJP1, PROJP2
3.1 Jul 2005 W.Landsman/C. Markwardt Set unprojectable points in
tangent projection to NaN
3.1.1 Jul 2005 Fixed 3.1 mod to work for scalars
3.2 Dec 2005 Fixed Airy projection for latitude centered at 90 deg
3.3 Aug 2007 R. Munoz, W.Landsman Correct treatment of PV1_2 and
PV2_2 parameters
3.4 Oct 2007 Sergey Koposov Support HEALPIX projection
3.4.1 June 2009 Check for range of validity of ZPN polynomial W.L.
3.5 May 2012 Benjamin Alan Weaver, Add nonstandard HEALCART
projection, Allow map_index to be > 25
(See astrolib/pro/wcssph2xy.pro)
WCSXY2SPH
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NAME:
WCSXY2SPH
PURPOSE:
Convert x and y (map) coordinates to spherical coordinates
EXPLANATION:
To convert x and y (map) coordinates to spherical (longitude and
latitude or sky) coordinates. This procedure is the inverse of
WCSSPH2XY.
This is a lower level procedure -- given a FITS header, the user will
usually use XYAD which will then call WCSXY2SPH with the appropriate
parameters.
CATEGORY:
Mapping and Auxilary FITS Routine
CALLING SEQUENCE:
wcsxy2sph, x, y, longitude, latitude, [map_type], [ CTYPE = ,$
FACE = ,PV2 = ,CRVAL =, CRXY =, LONGPOLE=, LATPOLE=]
INPUT PARAMETERS:
x - x coordinate of data, scalar or vector, in degrees, NOTE: x
increases to the left, not the right
y - y coordinate of data, same number of elements as x, in degrees
map_type - optional positional parameter, scalar corresponding to a
particular map projection. This is not a FITS standard, it is
simply put in to allow function similar to that of less general
map projection procedures (eg AITOFF). The following list gives
the map projection types and their respective numbers.
FITS Number Name Comments
code code
---- ------ ----------------------- -----------------------------------
DEF 0 Default = Cartesian
AZP 1 Zenithal perspective pv2_1 required
TAN 2 Gnomic AZP w/ pv2_1 = 0
SIN 3 Orthographic pv2_1, pv2_2 optional
STG 4 Stereographic AZP w/ pv2_1 = 1
ARC 5 Zenithal Equidistant
ZPN 6 Zenithal polynomial PV2_0, PV2_1....PV2_20 possible
ZEA 7 Zenithal equal area
AIR 8 Airy pv2_1 required
CYP 9 Cylindrical perspective pv2_1 and pv2_2 required
CAR 10 Cartesian
MER 11 Mercator
CEA 12 Cylindrical equal area pv2_1 required
COP 13 Conical perspective pv2_1 and pv2_2 required
COD 14 Conical equidistant pv2_1 and pv2_2 required
COE 15 Conical equal area pv2_1 and pv2_2 required
COO 16 Conical orthomorphic pv2_1 and pv2_2 required
BON 17 Bonne's equal area pv2_1 required
PCO 18 Polyconic
SFL 19 Sanson-Flamsteed
PAR 20 Parabolic
AIT 21 Hammer-Aitoff
MOL 22 Mollweide
CSC 23 Cobe Quadrilateralized inverse converges poorly
Spherical Cube
QCS 24 Quadrilateralized
Spherical Cube
TSC 25 Tangential Spherical Cube
SZP 26 Slant Zenithal perspective PV2_1,PV2_2, PV2_3 optional
HPX 27 HealPix
HCT 28 HealCart (Cartesian approximation of Healpix)
OPTIONAL KEYWORD PARAMETERS:
CTYPE - One, two, or three element vector containing 8 character
strings corresponding to the CTYPE1, CTYPE2, and CTYPE3
FITS keywords:
CTYPE[0] - first four characters specify standard system
('RA--','GLON' or 'ELON' for right ascension, galactic
longitude or ecliptic longitude respectively), second four
letters specify the type of map projection (eg '-AIT' for
Aitoff projection)
CTYPE[1] - first four characters specify standard system
('DEC-','GLAT' or 'ELAT' for declination, galactic latitude
or ecliptic latitude respectively; these must match
the appropriate system of ctype1), second four letters of
ctype2 must match second four letters of ctype1.
CTYPE[2] - if present must be the 8 character string,'CUBEFACE',
only used for spherical cube projections to identify an axis
as containing the face on which each x and y pair of
coordinates lie.
FACE - a input variable used for spherical cube projections to
designate the face of the cube on which the x and y
coordinates lie. Must contain the same number of elements
as X and Y.
CRVAL - 2 element vector containing standard system coordinates (the
longitude and latitude) of the reference point
CRXY - 2 element vector giving the x and y coordinates of the
reference point, if this is not set the offset of the x
coordinate is assumed to be 0.
LATPOLE - native latitude of the standard system's North Pole
LONGPOLE - native longitude of standard system's North Pole, default
is 180 degrees, numeric scalar
PV2 - Vector of projection parameter associated with latitude axis
PV2 will have up to 21 elements for the ZPN projection, up to 3
for the SIN projection and no more than 2 for any other
projection. The first element corresponds to PV2_1, the
second to PV2_2, etc.
OUTPUT PARAMETERS:
longitude - longitude of data, same number of elements as x, in degrees
latitude - latitude of data, same number of elements as x, in degrees
Longitude and latitude will be set to NaN, wherever elements of X,Y
have no corresponding longitude, latitude values.
NOTES:
The conventions followed here are described in more detail in the paper
"Representations of Celestial Coordinates in FITS" by Calabretta &
Greisen (2002, A&A, 395, 1077, also see
http://fits.gsfc.nasa.gov/fits_wcs.html). The general scheme
outlined in that article is to convert x and y coordinates into a
"native" longitude and latitude and then rotate the system into one of
three generally recognized systems (celestial, galactic or ecliptic).
This procedure necessitates two basic sections. The first converts
x and y coordinates to "native" coordinates while the second converts
"native" to "standard" coordinates. The first section contains the
guts of the code in which all of the map projection is done. The
second step is performed by WCS_ROTATE and only involves rotation of
coordinate systems. WCSXY2SPH can be called in a form similar to
AITOFF, EQPOLE, or QDCB by calling wcsxy2sph with a fifth parameter
specifying the map projection by number and by not using any of the
keywords related to the map projection type (eg ctype1 and ctyp2).
PROCEDURE:
The first task of the procedure is to do general error-checking to
make sure the procedure was called correctly and none of the
parameters or keywords conflict. This is particularly important
because the procedure can be called in two ways (either using
FITS-type keywords or using a number corresponding a map projection
type). All variables are converted into double precision values.
The second task of the procedure is to take x and y coordinates and
convert them into "native" latitude and longitude coordinates.
Map-specific error-checking is done at this time. All of the
equations were obtained from "Representations of Celestial
Coordinates in FITS" and cases needing special attention are handled
appropriately (see the comments with individual map projections for
more information on special cases). WCS_ROTATE is then called to
convert the "native" coordinates to "standard" coordinates by rotating
the coordinate system. This rotation is governed by the keywords
CRVAL, and LONGPOLE. The transformation is a straightforward
application of euler angles. Finally, longitude values are converted
into the range from 0 to 360 degrees.
COMMON BLOCKS:
none
PROCEDURES CALLED:
WCS_ROTATE
AUTHOR:
Rick Balsano
MODIFICATIONS/REVISION LEVEL:
1.1 8/31/93
1.2 9/12/93 W. Landsman Vectorized CRXY, CRVAL, CTYPE
1.3 29/12/93 I. Freedman Eliminated LU decomposition
1.4 22/09/94 W. Landsman If scalar input, then scalar output
1.5 02/03/05 W. Landsman Change variable name BETA for V4.0 compatibility
1.6 06/07/05 W. Landsman Change loop index from integer to long
1.7 02/18/99 W. Landsman Fixed implementation of ARC algorithm
1.8 June 2003 W. Landsman Update conic projections, add LATPOLE keyword
1.81 Sep 2003 W. Landsman Avoid divide by zero
1.82 Sep 2003 W. Landsman CTYPE keywords need not be 8 characters
1.83 Sep 2003 W. Landsman Preserve input array sizes
1.9 Jan 2004 W. Landsman don't modify scalars, fix PARabolic code
2.0 Feb 2004 W. Landsman Fix AIR and AZP projections
2.1 Feb 2004 W. Landsman Fix tangent projection for matrix input
3.0 May 2004 W. Landsman Support extended SIN (=NCP), slant zenithal
(SZP), and zenithal polynomial (ZPN) projections, use
PV2 keyword vector instead of PROJP1, PROJP2
3.1 May 2004 W. Landsman/J. Ballet Handle NaN values, flag invalid output
for AITOFF projection
3.1.1 Dec 2005 W. Landsman/W. Thompson Fixed problem with Airy projection
centered on 90 degree latitude
3.1.2 May 2006 W. Landsman/Y.Sato Fix problem selecting the correct root
for the ZPN projection
3.2 Aug 2007 W. Landsman Correct treatment of PVi_j parameters
3.3 Oct 2007 Sergey Koposov Support HEALPIX projection
3.4 May 2012 Benjamin Alan Weaver, Add nonstandard HEALCART
projection, Allow map_index to be > 25
(See astrolib/pro/wcsxy2sph.pro)
WCS_DEMO
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NAME:
WCS_DEMO
PURPOSE:
Demonstrate the basic capabilities of procedures WCSSPH2XY & WCSXY2SPH
CATEGORY:
Mapping and Auxilary FITS Demo Routine
CALLING SEQUENCE:
.run wcs_demo: compiles wcs_demo and the supporting demo routines
wcs_demo: run the demo
INPUT PARAMETERS:
none
OUTPUT PARAMETERS:
none
PROCEDURE:
This is a demo program which is meant to call the routines
wcssph2xy.pro and wcsxy2sph.pro. Since the purpose of this
routine is both to show what the routines can do and what the
user has to do, a file is created with all of the commands
needed to complete the desired operation. Wcs_demo actually
executes this command file, so the user can exactly duplicate
the results by simply re-executing this file. Also, this
allows a user to edit an already existing file which calls
wcssph2xy.pro and wcsxy2sph.pro properly and extend the file's
usefulness. This demo program allows several possible tests.
The first option is to simply draw a grid of evenly spaced
latitude and longitude lines in a particular map transformation.
Another possibility is to do a full loop, creating a Cartesian
grid of latitude and longitude lines and calling wcssph2xy.pro
to convert them to a particular map. Then, wcsxy2sph.pro is
called to invert the process and the difference between the
original and final latitudes and longitudes can be plotted.
This allows one to assess the level of the numerical errors
introduced by the mapping routines. A third possible option is to
look at some of the map transformations and include rotations of
the reference points so that a different perspective is given.
COMMON BLOCKS:
none
PROCEDURES CALLED:
SPHDIST(), WCSXY2SPH, WCSSPH2XY
COPYRIGHT NOTICE:
Copyright 1991, The Regents of the University of California. This
software was produced under U.S. Government contract (W-7405-ENG-36)
by Los Alamos National Laboratory, which is operated by the
University of California for the U.S. Department of Energy.
The U.S. Government is licensed to use, reproduce, and distribute
this software. Neither the Government nor the University makes
any warranty, express or implied, or assumes any liability or
responsibility for the use of this software.
AUTHOR:
Rick Balsano
MODIFICATIONS/REVISION LEVEL:
1.1 8/31/93
1.2 3/19/96 - J. Bloch - LANL
- Made compatible with wcslib-2.2 by Calabretta.
Converted to IDL V5.0 W. Landsman September 1997
Updated for conical projections W. Landsman July 2003
(See astrolib/pro/wcs_demo.pro)
WCS_GETPOLE
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NAME:
WCS_GETPOLE
PURPOSE:
Compute the coordinates of the native pole for a non-polar projection
EXPLANATION:
For non-polar (cylindrical or conic) projections, the native pole is
not at the reference point, and WCS_GETPOLE is used to determine the
position of the native pole. See section 2.4 of the paper
"Representation of Celestial Coordinates in FITS" by Calabretta
Greisen (2002, A&A, 395, 1077, also available at
http://fits.gsfc.nasa.gov/fits_wcs.html Called by WCS_ROTATE
CALLING SEQUENCE:
WCS_GETPOLE, crval, lonpole, theta0, alpha_p, delta_p, LATPOLE= ]
INPUT PARAMETERS:
crval - 2 element vector containing standard system coordinates (the
longitude and latitude) of the reference point in degrees
lonpole - native longitude of the celestial North Pole (degrees)
theta0 - native latitude of the fiducial point
OUTPUT PARAMETERS:
alpha_p, delta_p - celestial longitude and latitude of the native pole
(Radians)
OPTIONAL KEYWORD INPUT PARAMETERS:
LATPOLE - native latitude of the celestial North Pole (degrees)
REVISION HISTORY:
Written W. Landsman June, 2003
Fix calculation when theta0 is not 0 or 90 February 2004
E. Hivon: alpha_p, delta_p consistenly in Radians May 2010
(See astrolib/pro/wcs_getpole.pro)
WCS_ROTATE
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NAME:
WCS_ROTATE
PURPOSE:
Rotate between standard (e.g. celestial) and native coordinates
EXPLANATION:
Computes a spherical coordinate rotation between native coordinates
and standard celestial coordinate system (celestial, Galactic, or
ecliptic). Applies the equations in Appendix B of the paper
"Representation of Celestial Coordinates in FITS" by Calabretta
Greisen (2002, A&A, 395, 1077). Also see
http://fits.gsfc.nasa.gov/fits_wcs.html
CATEGORY:
Mapping and Auxiliary FITS Routine
CALLING SEQUENCE:
WCS_ROTATE, longitude, latitude, phi, theta, crval,
[LONGPOLE = , LATPOLE = , /REVERSE, /ORIGIN ]
INPUT PARAMETERS:
crval - 2 element vector containing standard system coordinates (the
longitude and latitude) of the reference point
INPUT OR OUTPUT PARAMETERS
longitude - longitude of data, scalar or vector, in degrees, in the
standard celestial coordinate system
latitude - latitude of data, same number of elements as longitude,
in degrees
phi - longitude of data in the native system, in degrees, scalar or
vector
theta - latitude of data in the native system, in degrees, scalar or
vector
If the keyword(REVERSE) is set then phi and theta are input parameters
and longitude and latitude are computed. Otherwise, longitude and
latitude are input parameters and phi and theta are computed.
OPTIONAL KEYWORD INPUT PARAMETERS:
ORIGIN - If this keyword is set and non-zero, then the reference point
given by CRVAL in the native system is assumed to be at the
origin of the coordinates, rather than at the North Pole.
ORIGIN should be set for cylindrical projections (Cylindrical
perspective-CYP, Cartesian - CAR, Mercator - MER, Cylindrical
Equal area - CEA) and conventional projections (Bonne's equal
area - BON, Polyconic - PCO, Sinusoidal - GLS, Parabolic - PAR,
Aitoff - AIT, Mollweide - MOL, COBE quadrilateralized sphere -
CSC, Quadrilateralized Spherical Cube - QSC, and Tangential
Spherical Cube - TSC)
LONGPOLE - native longitude of standard system's North Pole, default
for a Zenithal system is 180 degrees
LATPOLE - native latitude of the standard system's North Pole
/REVERSE - if set then phi and theta are input parameters and longitude
and latitude are computed. By default, longitude and
latitude are input parameters and phi and theta are computed.
REVISION HISTORY:
Written W. Landsman December, 1994
Fixed error in finding North Pole if /ORIGIN and LONGPOLE NE 180
Xiaoyi Wu and W. Landsman, March, 1996
Fixed implementation of March 96 error, J. Thieler, April 1996
Updated to IDL V5.0 W. Landsman December 1997
Fixed determination of alpha_p if /ORIGIN and LONGPOLE EQ 180
W. Landsman May 1998
Ensure argument of ASIN() is -1
(See astrolib/pro/wcs_rotate.pro)
WEBGET()
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NAME:
WEBGET()
PURPOSE:
Use the IDL SOCKET procedure to get data from http servers
EXPLANATION:
WEBGET() can access http servers - even from behind a firewall -
and perform simple downloads. Currently, text and FITS files can be
accessed.
CALLING SEQUENCE:
a=webget(URL)
INPUTS:
URL - scalar string giving a fully qualified url of the form
'http://server.eso.org/path/file.html'. WEBGET() can
also use other valid URLs that contain 'GET' or 'POST' codes.
OPTIONAL INPUT KEYWORD PARAMETERS:
COPYFILE - if set to a valid filename (file must have write permission),
the data contents of the web server's answer is copied to that
file.
HTTP10 - If set, then use the HTTP 1.0
POST - if set to a structure, the structure tags and values
will be used as post variables and POST'ed to the URL.
If POST is not set, the normal HTTP GET is used to
retrieve the URL.
/SILENT - If set, the information error messages are suppressed
TIMEOUT - Integer scalar giving number of seconds to wait to connect
or for data to arrive before giving up and issuing an error.
Default=15 seconds
OUTPUTS: A structure with the following fields:
.Header - the HTTP header sent by the server
.Text - The text part of the downloaded file. If the
content type of the file was not of class
'text', this will be an empty string.
.ImageHeader - Header file of a FITS-image. FITS images
are read when the content type is
'image/fits' or 'application/octet-stream'
(for dss-access). If the file is not a FITS
image, this will be an empty string.
.Image - The FITS image read from the server. If the file
did not contain a FITS image, this will be zero.
RESTRICTIONS:
The mime-type recognition is extremely limited. Only the content-type is
determined. Any text-file will be stored in out.Text. The only other
category which can be fetched is FITS files, which will be stored in
out.Image and out.ImageHeader.
PROXY: If you are behind a firewall and have to access the net through a
Web proxy, set the environment variable 'http_proxy' to point to
your proxy server and port, e.g.
'setenv http_proxy=http://web-proxy.mpia-hd.mpg.de:3128'
The URL *MUST* begin with "http://".
PROCEDURE:
Open a socket to the webserver and download the header. After deciding
whether it is text or binary, either store the text or try to read a
FITS file.
EXAMPLE:
IDL> a=webget('http://www.mpia.de/index.html')
IDL> print,a.Text
or
> PointingRA=0.0
> PointingDE=30.0
> QueryURL = strcompress("http://archive.eso.org/dss/dss/image?ra="+$
> string(PointingRA)+$
> "&dec="+$
> string(PointingDE)+$
> "&x=10&y=10&Sky-Survey=DSS1&mime-type=download-fits", $
> /remove)
> a=webget(QueryURL)
> tvscl,a.Image
> print,a.ImageHead
MODIFICATION HISTORY:
Written by M. Feldt, Heidelberg, Oct 2001
Use /swap_if_little_endian keyword to SOCKET W. Landsman August 2002
Less restrictive search on Content-Type W. Landsman April 2003
Modified to work with FIRST image server- A. Barth, Nov 2006
Better recovery from errors W. Landsman April 2007
Add support for POST access J.D. Smith June 2007
Recognize "fits" image type used by SKYVIEW W. Landsman June 2007
Upgraded, partially, to HTTP 1.1 M. Perrin, July 2007
The HTTP 1.1 support is presently INCOMPLETE: virtual servers are
supported, but chunked transfer encoding is not yet supported, so
technically this is not fully HTTP 1.1 compliant.
Added http10 keyword W. Landsman August 2007
Assume since V5.6, sockets always available W. Landsman Nov 2007
Fix problem when using proxy server W. Landsman July 2008
Fix problem with /SILENT keyword W. Landsman Jan 2009
Added check for missing Mime TYPE in CLASSANDTYPE, Zarro, December 2011
Timeout applies to connecting as well as reading, default is now 15
seconds W Landsman January 2012
(See astrolib/pro/webget.pro)
WFPC2_METRIC
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NAME:
WFPC2_METRIC
PURPOSE:
Compute the distortion in a WFPC2 image and optionally return coordinates
EPLANATION:
Uses the distortion solution of Anderson & King (2003, PASP, 115, 113)
Pixel 424, 424 on each chip remains fixed, and other pixel positions are
mapped to remove nonlinearities. If /GLOBAL is set, then all chips are
put on the same reference frame where pixel 424, 424 in the WF3 chip
remains fixed.
CALLING SEQUENCE:
WFPC2_METRIC, xin, yin, xout, yout, [ChipNum, HEADER=, /GLOBAL
YEAR =, FILTER=
or
WFPC2_METRIC, xin, yin, a, d, HEADER=, /RAdec, /GLOBAL ]
INPUTS:
XIN, YIN - X,Y positions (0-799) on a WFPC2 chip in
IDL convention (first pixel is 0,0), scalar or vectors
OUTPUTS:
XOUT, YOUT - X,Y positions in the undistorted frame, same number of
elements as XIN, YIN
or if /RADEC is set
AA, DD - Right ascension and declination (in degrees) corresponding
to the input coordinates after distortion correction.
OPTIONAL INPUT:
ChipNum - Integer 1, 2, 3, or 4 specifying the WFPC2 chip number
1-PC, 2-WF2, 3-WF3, 4-WF4. If not supplied, then WFPC2_METRIC
will try to read the value from the DETECTOR in the FITS header.
OPTIONAL INPUTS:
/GLOBAL - If set, then positions are returned in a master reference
frame with pixel 424,424 of WF3 remaining fixed. Thus,
information concerning the interchip separation and
orientation (with a weak dependence on time and filter) is
incorporated.
Header - FITS header with astrometry for a particular chip.
If both /RADec and /Global are set, then the header must be
from the WF3 chip.
/RADec - If set, then astrometry information in the FITS header (which
must be supplied as a keyword) is used to convert the output
to Right Ascension and declination (both in degrees).
FILTER - Filter name needed if /GLOBAL is set, must be either 'F300W'
'F336W', 'F439W', 'F555W' or 'F814W'; otherwise the plate scale
for F555W is assumed. WFPC2_METRIC will try to read this
value from the FITS header if not supplied as a keyword.
YEAR - Observation year including fraction (e.g. 1998.56) needed if
/GLOBAL is set. WFPC2_METRIC will try to read this value from
the FITS header if not supplied as a keyword. The time
correction is currently applied through the year 2002; later
dates will use the year 2002 correction.
EXAMPLES:
(1) Find the undistorted X,Y coordinates of position 682.3,234.2 on chip 1
(the PC chip).
IDL> WFPC2_METRIC, 682.3, 234.2, xout, yout, 1
==> xout = 681.13 yout = 235.05
(2) Determine the RA and Dec of position 682.3, 234.2 on chip 1 on the
WFPC2 image U2Z30201T
IDL> WFPC2_READ, 'u2z30201t.c0h', im,h ;Get header for chip 1
IDL> WFPC2_METRIC, 682.3, 234.2, aa, dd, header= h,/RADec
IDL> print, adstring(aa,dd,2)
05 20 53.572 -69 35 18.17
Note that a chip number did not need to be specified since its value
is in the FITS header
(3) As above, but now compute coordinates in the global frame, needed
for example, to compute the distance between stars on two different
chips.
First get headers for chips 1 and 3
IDL> WFPC2_READ, 'u2z30201t.c0h', im1,h1, im3,h3,num=[1,3]
IDL> WFPC2_METRIC, 682.3, 234.2, aa, dd, 1, header=h3,/RADec,/GLOBAL
IDL> print, adstring(aa,dd,2)
05 20 53.513 -69 35 17.98
Note that with /GLOBAL set, that the header must be for WF3, even
though coordinates are being computed for chip 1. Also note that
the time and filter will be read from the FITS header. Finally,
note that the coordinates given in examples (2) and (3) differ
slightly, because the chip separations incorporated in the FITS
headers differ slightly from those in the Anderson & King solution.
PROCEDURES USED:
LINTERP, SXPAR(), XYAD, YMD2DN()
REVISION HISTORY:
Written W. Landsman March 2003
(See astrolib/pro/wfpc2_metric.pro)
WFPC2_READ
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NAME:
WFPC2_READ
PURPOSE:
Read WFPC2 images in either FITS or STSDAS format into IDL variables.
EXPLANATION:
This a versatile procedure for reading Wide Field Planetary Camera 2
(WFPC2) images. One can read either multi-extension FITS or STSDAS or
STSDAS converted to FITS format, and specific
chip or chips. One can also read all four chips into a "batwing" mosaic--
so-called because the PC chip (chip 1) has a plate scale of 0.045", while
the other three WF chips have a plate scale of 0.1"
CALLING SEQUENCE:
WFPC2_READ,filename,chip1,hdr1,chip2,hdr2,chip3,hdr3,chip4,hdr4
or
WFPC2_READ,filename,chip,hdr, NUM_CHIP = [1,2,3,4], [/TRIM, PATH = ]
or
WFPC2_READ,filename,image,hdr,/BATWING
INPUTS:
filename - Name of FITS or STSDAS file with a stack of images from
the four WF/PC-2 chips, followed by a FITS ASCII
table with header parameters for each chip. If the file
name extension ends in 'h' then it is assumed to be an
STSDAS file. If no extension is supplied, and the file is
is not found, then WFPC2_READ first tries appending a '.fits'
extension, and then tries appending a '.c0h' extension.
The file may als be gzip compressed (with a .gz extension)
INPUT KEYWORD PARAMETERS:
NUM_CHIP - Integer scalar or vector, subset of 1, 2, 3, 4, specifying
particular chip numbers to read. Outputs will be in same
order as specification of subset. (See Example 2.)
/TRIM - If set, trim off areas with no image and re-orient so that
all the chips have a common orientation suitable for insertion
into "bat-wing" mosaic (no image distortion removal, however).
PATH - scalar string specifying a !PATH-like list of directories
in which to search for the file. Default is to look only
in the current directory.
/BATWING - Return a 1600 x 1600 array containing all four chips in a
"bat wing" mosaic formation. This image is mainly for
display purposes, since the PC chip is compressed to match the plate
scale of the WF chips. In addition, a small astrometry error
is introduced since chips do not have the same rotation, nor
are they aligned at the integer pixel level.
OUTPUTS:
chipN - 800 X 800 image from chip N. If /TRIM is set then the output
size is somewhat smaller (e.g. 756 x 757)
headerN - Individual FITS header for chip N with correct astrometry.
PROCEDURES USED:
For FITS I/O: FITS_CLOSE, FITS_OPEN, FITS_READ
For STSDAS I/O: EXTGRP, FTGET(), SXOPEN, SXREAD()
Other procedures: CHECK_FITS, FDECOMP, FIND_WITH_DEF(), FREBIN, HEXTRACT,
HROTATE, SXADDHIST, SXADDPAR, SXPAR()
EXAMPLE:
(1) Read all four chips of the FITS file u2ou0201t_c0f.fits
IDL> wfpc2_read,'u2ou0201t_c0f',c1,h1,c2,h2,c3,h3,c4,h4
(2) Note that supplying the .fits extension is optional. Now read only
chips 1 (the PC chip) and 3. Trim off portions of the arrays where
there is no image.
IDL> wfpc2_read,'u2ou0201t_c0f',c1,h1,c3,h3,num=[1,3],/trim
(3) Note that with the /TRIM option the output chip sizes are no longer
800 x 800 but odd sizes such as 770 by 753. Now read all 4 chips
into a 1600 x 1600 "batwing" mosaic
IDL> wfpc2_read,'u2ou0201t_c0f',im,h,/batwing
MODIFICATION HISTORY:
Written by W. Landsman, Raytheon STX, for IDL V5.0 June 1998
Based on code by Robert Hill, Raytheon STX
Better astrometry of PC image in "batwing" configuration, W. Landsman
August 1999
Use vector call to SXADDHIST W. Landsman March 2003
Don't use EXECUTE() for V6.1 or later W. Landsman Dec 2006
Assume since V6.1 W. Landsman June 2009
Ability to read multi-extension format FITS W. Landsman May 2010
Correct header in MEF form when only reading PC chip. W.L. July 2010
(See astrolib/pro/wfpc2_read.pro)
WHERENAN()
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NAME:
WHERENAN()
PURPOSE:
Find the indices of all big-endian NaN values in an array. OBSOLETE
EXPLANATION:
Find the positions of all values within an array that correspond to the
big-endian NaN (not-a-number) special values.
THIS PROCEDURE ONLY IDENTIFIES BIG_ENDIAN NaN VALUES. DO NOT USE IT
TO IDENTIFY NaN VALUES IN GENERAL. Instead, to identify NaN values on
the host machine use the FINITE() function
IDL> result = where( finite(array,/NAN) )
The main purpose of this routine is to catch NaN special values
written in big_endian format (e.g. FITS data) on a little endian
machine prior to conversion with e.g. IEEE_TO_HOST. It was needed
many years ago because VMS machines could not handle big-endian
special values, but this routine is now kept only for backwards
compatibility.
CALLING SEQUENCE:
Result = WHERENAN( ARRAY [, COUNT ] )
INPUT PARAMETERS:
ARRAY = Array to test against the IEEE NaN special values. Must be
of either floating point, double-precision, or complex type.
OUTPUTS:
The result of the function is the indices of all values of ARRAY
corresponding to the IEEE NaN specification, similar to the IDL WHERE
function.
OPTIONAL OUTPUT PARAMETERS:
COUNT = Number of values found corresponding to IEEE NaN.
SIDE EFFECTS:
If no NaN values are found, or if ARRAY is not of type float, double
precision, or complex, then -1 is returned, and COUNT is set to 0.
RESTRICTIONS:
ARRAY must be of type float, double-precision, or complex.
PROCEDURE:
The bit patterns of the numbers being tested are compared against the
IEEE NaN standard.
MODIFICATION HISTORY:
William Thompson, Feb. 1992.
William Thompson, Oct. 1992, fixed bug regarding order of bytes on VAX
machines.
Converted to IDL V5.0 W. Landsman September 1997
(See astrolib/pro/wherenan.pro)
WHERE_TAG
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NAME:
WHERE_TAG
PURPOSE:
Like WHERE but works on structure tag names
EXPLANATION:
Obtain subscripts of elements in structure array for which
a particular Tag has values in a range or matching specified values.
Like the WHERE function but for use with structures
CATEGORY:
Structures
CALLING SEQUENCE:
w = where_tag( struct, [ Nfound, TAG_NAME=, TAG_NUMBER = , RANGE =,
VALUES =, RANGE =, ISELECT =, /NOPRINT ]
INPUTS:
Struct = structure array to search.
INPUT KEYWORDS:
User *must* specify (1) TAG_NAME or TAG_NUMBER to search, and (2)
the VALUES or RANGE to search on
TAG_NAME = Scalar string specifying Tag Name
TAG_NUMBER = otherwise give the Tag Number,
RANGE = [min,max] range to search for in Struct,
VALUES = one or array of numbers to match for in Struct,
ISELECT= specifies indices to select only part of structure array,
(use it to recycle subscripts from previous searches).
/NOPRINT = suppress informational messages about nothing found.
OUTPUTS:
Nfound = # of occurences found.
RESULT:
Function returns subscripts (indices) to desired elements.
EXAMPLES:
Suppose STR is a structure with tags CAT_NO:indgen(10), and
NAME:strarr(10). Find the indices where STR.CAT_NO is
between 3 and 5.
IDL> print, WHERE_TAG( str, TAG_NAME = 'CAT_NO', VALUE = [3,4,5] ) ;or
IDL> print, WHERE_TAG( str, TAG_NUM = 0, RANGE = [3,5])
PROCEDURE:
Get tag number and apply the WHERE function appropriately.
MODIFICATION HISTORY:
written 1990 Frank Varosi STX @ NASA/GSFC
Stop printing "Tag not found" with /NOPRINT, CD Pike 8-Jun-93
Use STRJOIN for display W.L. July 2009
(See astrolib/pro/where_tag.pro)
WRITEFITS
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NAME:
WRITEFITS
PURPOSE:
Write IDL array and header variables to a disk FITS file.
EXPLANATION:
A minimal FITS header is created if not supplied.
WRITEFITS works for all types of FITS files except random groups
CALLING SEQUENCE:
WRITEFITS, filename, data [, header, /APPEND, /COMPRESS, /CHECKSUM]
INPUTS:
FILENAME = String containing the name of the file to be written.
DATA = Image array to be written to FITS file. If DATA is
undefined or a scalar, then only the FITS header (which
must have NAXIS = 0) will be written to disk
OPTIONAL INPUT:
HEADER = String array containing the header for the FITS file.
If variable HEADER is not given, the program will generate
a minimal FITS header.
HEAP - A byte array giving the heap area following, e.g. a variable
length binary table
OPTIONAL INPUT KEYWORD:
/APPEND - If this keyword is set then the supplied header and data
array are assumed to be an extension and are appended onto
the end of an existing FITS file. If the file does not
exist, then WRITEFITS will create one with a minimal primary
header (and /EXTEND keyword) and then append the supplied
extension header and array. Note that the primary
header in an existing file must already have an EXTEND
keyword to indicate the presence of an FITS extension.
/COMPRESS - If this keyword is set, then the FITS file is written as
a gzip compressed file. An extension '.gz' is appended to
to the file name if it does not already exist. The /COMPRESS
option is incompatible with the /APPEND option.
/Checksum - If set, then the CHECKSUM keywords to monitor data integrity
will be included in the FITS header. For more info, see
http://heasarc.gsfc.nasa.gov/docs/heasarc/fits/checksum.html
By default, checksum keywords will updated if they are already
in the FITS header.
NaNvalue - Value in the data array which represents missing pixels.
This keyword should only used when missing pixels are not
represented by NaN values in the input array.
OUTPUTS:
None
RESTRICTIONS:
(1) It recommended that BSCALE and BZERO not be used (or set equal
to 1. and 0) except with integer data
(2) WRITEFITS will remove any group parameters from the FITS header
(3) As of Feb 2008, WRITEFITS no longer requires the primary header of a
FITS file with extension contain the EXTEND keyword, consistent with
Section 4.4.2.1 of the FITS 3.0 standard. A warning is still
given. See http://fits.gsfc.nasa.gov/fits_standard.html
EXAMPLE:
Write a randomn 50 x 50 array as a FITS file creating a minimal header.
IDL> im = randomn(seed, 50, 50) ;Create array
IDL> writefits, 'test', im ;Write to a FITS file "test"
PROCEDURES USED:
CHECK_FITS, FITS_ADD_CHECKSUM, MKHDR, MRD_HREAD, SXDELPAR, SXADDPAR,
SXPAR()
MODIFICATION HISTORY:
WRITTEN, Jim Wofford, January, 29 1989
Added call to IS_IEEE_BIG() W. Landsman Apr 96
Make sure SIMPLE is written in first line of header W. Landsman Jun 97
Use SYSTIME() instead of !STIME W. Landsman July 97
Create a default image extension header if needed W. Landsman June 98
Write unsigned data types W. Landsman December 1999
Update for IDL V5.3, add /COMPRESS keyword W. Landsman February 2000
Correct BZERO value for unsigned data W. Landsman July 2000
Eliminate duplication of input array if possible W. Landsman April 2001
Use FILE_SEARCH for V5.5 or later W. Landsman April 2002
Create the file if not already present and /APPEND is set
W. Landsman September 2002
Proper call to MRD_HREAD if /APPEND is set W. Landsman December 2002
Added /CHECKSUM keyword W. Landsman December 2002
Restored NANvalue keyword, William Thompson, October 2003
Write BZERO in beginning of header for unsigned integers WL April 2004
Added ability to write heap array WL October 2004
Correct checksum if writing heap array WL November 2004
Assume since V5.5, no VMS support, use file_search() WL September 2006
Set nbytes variable to LONG64 for very large files WL May 2007
Update CHECKSUM keywords if already present WL Oct 2007
EXTEND keyword no longer required in FITS files with extensions WL Feb 2008
Bug fix when filename ends with '.gz' and COMPRESS is used,
the output file must be compressed S. Koposov June 2008
Introduce V6.0 notation W.L. Nov. 2010
Set /APPEND if XTENSION specifies a table W.L. July 2012
(See astrolib/pro/writefits.pro)
XDISPSTR
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NAME:
XDISPSTR
PURPOSE:
Display a string array in a text widget with a simple search capability.
EXPLANATION:
Similar to the IDL XDISPLAYFILE procedure but includes a search capbility.
CALLING SEQUENCE:
xdispstr, array, [/BLOCK, WIDTH= , HEIGHT=, TITLE=, GROUP_LEADER=, FONT=
TOP_LINE = ]
INPUT PARAMETER:
array - String array (.e.g. FITS header) to be displayed
OPTIONAL INPUT KEYWORD PARAMETERS:
block - Set to 1 to make widget blocking. Default = block=0
width, height - Scalars giving number of characters per line, number
of lines. Default = 80x24
title - Scalar Title for outermost base widget.
group_leader - Group leader for top level base.
top_line - first line in the string array to display (default is 0)
font - Display font for text.
MODIFICATION HISTORY:
Written by R. S. Hill, RITSS, 17 Nov 2000
Use cumulative keyword to TOTAL W. Landsman May 2006
(See astrolib/pro/xdispstr.pro)
XMEDSKY
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NAME:
XMEDSKY
PURPOSE:
Subtract sky from an image as a 1-D function of X
EXPLANATION:
This procedure is designed to remove the sky from slitless spectra.
The sky is assumed to vary with wavelength (along a row) but not with
position (along a column). The sky is computed as the
column-by-column median of pixels within 3 sigma of the image global
median. This procedure is called by the cosmic ray rejection routine
CR_REJECT
CALLING SEQUENCE:
XMEDSKY, Image, Bkg, [ CLIP=[x0, x1, y0, y1], NSIG= ]
INPUTS:
Image: Input image for which sky vector is to be computed.
INPUT KEYWORD PARAMETERS:
CLIP: [x0, x1, y0, y1]: region of image to be used for all
statistical computations. Default is to use the entire
image. For STIS 1024 x 512 slitless spectra, the suggested
value is CLIP = [32,1023,12,499]
NSIG: Positive scalar giving the number of sigma a pixel must be above
the global median to be reject. Default is 3 sigma.
OUTPUT PARAMETER:
Bkg: Vector of sky values.
;
MODIFICATION HISTORY:
Written by: R. S. Hill, Hughes STX, 20 Oct. 1997
Converted to V5.0, use STDDEV() W. Landsman June 1998
Check for valid WHERE, added NSIG keyword W. Landsman December 2000
Assume since V5.1 so always use STDDEV W. Landsman Feb 2004
Assume since V5.6 use DIMEN keyword to MEDIAN W. Landsman Jan 2008
(See astrolib/pro/xmedsky.pro)
XY2AD
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NAME:
XY2AD
PURPOSE:
Compute R.A. and Dec from X and Y and a FITS astrometry structure
EXPLANATION:
The astrometry structure must first be extracted by EXTAST from a FITS
header. The offset from the reference pixel is computed and the CD
matrix is applied. If distortion is present then this is corrected.
If a WCS projection (Calabretta & Greisen 2002, A&A, 395, 1077) is
present, then the procedure WCSXY2SPH is used to compute astronomical
coordinates. Angles are returned in degrees.
XY2AD is meant to be used internal to other procedures.
For interactive purposes use XYAD.
CALLING SEQUENCE:
XY2AD, x, y, astr, a, d
INPUTS:
X - row position in pixels, scalar or vector
Y - column position in pixels, scalar or vector
X and Y should be in the standard IDL convention (first pixel is
0), and not the FITS convention (first pixel is 1).
ASTR - astrometry structure, output from EXTAST procedure containing:
.CD - 2 x 2 array containing the astrometry parameters CD1_1 CD1_2
in DEGREES/PIXEL CD2_1 CD2_2
.CDELT - 2 element vector giving physical increment at reference pixel
.CRPIX - 2 element vector giving X and Y coordinates of reference pixel
(def = NAXIS/2)
.CRVAL - 2 element vector giving R.A. and DEC of reference pixel
in DEGREES
.CTYPE - 2 element vector giving projection types
.LONGPOLE - scalar longitude of north pole
.LATPOLE - scalar giving native latitude of the celestial pole
.PV2 - Vector of projection parameter associated with latitude axis
PV2 will have up to 21 elements for the ZPN projection, up to 3
for the SIN projection and no more than 2 for any other
projection
.DISTORT - Optional substructure specifying distortion parameters
OUTPUT:
A - R.A. in DEGREES, same number of elements as X and Y
D - Dec. in DEGREES, same number of elements as X and Y
RESTRICTIONS:
Note that all angles are in degrees, including CD and CRVAL
Also note that the CRPIX keyword assumes an FORTRAN type
array beginning at (1,1), while X and Y give the IDL position
beginning at (0,0). No parameter checking is performed.
NOTES:
AD2XY tests for presence of WCS coordinates by the presence of a dash
in the 5th character position in the value of CTYPE (e.g 'DEC--SIN').
PROCEDURES USED:
TAG_EXIST(), WCSXY2SPH
REVISION HISTORY:
Written by R. Cornett, SASC Tech., 4/7/86
Converted to IDL by B. Boothman, SASC Tech., 4/21/86
Perform CD multiplication in degrees W. Landsman Dec 1994
Understand reversed X,Y (X-Dec, Y-RA) axes, W. Landsman October 1998
Consistent conversion between CROTA and CD matrix W. Landsman Oct. 2000
No special case for tangent projection W. Landsman June 2003
Work for non-WCS coordinate transformations W. Landsman Oct 2004
Use CRVAL reference point for non-WCS transformation W.L. March 2007
Use post V6.0 notation W.L. July 2009
(See astrolib/pro/xy2ad.pro)
XYAD
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NAME:
XYAD
PURPOSE:
Use a FITS header to convert pixel (X,Y) to world coordinates
EXPLANATION:
Use astrometry in a FITS image header to compute world
coordinates in decimal degrees from X and Y.
If spherical coordinates (Calabretta & Greisen 2002, A&A, 395, 1077) are
not present, then XYAD will still perform the transformation specified
by the CD, CRVAL, and CRPIX keywords.
CALLING SEQUENCE:
XYAD, HDR ;Prompt for X and Y positions
XYAD, HDR, X, Y, A, D, [ /PRINT, /Galactic, /Celestial, /Ecliptic,
ALT =, PRECISION=]
INPUTS:
HDR - FITS Image header containing astrometry info
OPTIONAL INPUTS:
X - row position in pixels, scalar or vector
Y - column position in pixels, scalar or vector
X and Y should be in IDL convention, (first pixel is (0,0) where
the integral value corresponds to the center of the pixel.)
OPTIONAL OUTPUT:
A - Output longitude in decimal DEGREES (for spherical coordinates),
same number of elements as X and Y. For celestial
coordinates, this is the Right ascension.
D - Output latitude in decimal DEGREES. For celestial coordinates,
this is the declination.
OPTIONAL KEYWORD INPUT:
ALT - single character 'A' through 'Z' or ' ' specifying an alternate
astrometry system present in the FITS header. The default is
to use the primary astrometry or ALT = ' '. If /ALT is set,
then this is equivalent to ALT = 'A'. See Section 3.3 of
Greisen & Calabretta (2002, A&A, 395, 1061) for information about
alternate astrometry keywords.
PRECISION - Integer scalar (0-4) specifying the number of digits
displayed after the decimal of declination. The RA is
automatically one digit more. See ADSTRING() for more info.
Default value is 1, and the keyword is ignored if results are not
displayed at the terminal
/PRINT - If this keyword is set and non-zero, then results are displayed
at the terminal.in both decimal and sexagesimal notation.
The default for XYAD is to return the coordinate system present in
in the FITS header. However, the following mutually exclusive
keywords can be used to convert to a particular coordinate system:
/CELESTIAL - Output is Right Ascension and declination
/ECLIPTIC - Output is Ecliptic longitude and latitude
/GALACTIC - Output is Galactic longitude and latitude
OPERATIONAL NOTES:
If less than 5 parameters are supplied, or if the /PRINT keyword is
set, then the computed astronomical coordinates are displayed at the
terminal.
If this procedure is to be used repeatedly with the same header,
then it would be faster to use XY2AD.
EXAMPLE:
A FITS header, hdr, contains astrometric information in celestial
coordinates. Find the RA and Dec corresponding to position X=23.3
Y = 100.2 on an image
IDL> xyad, hdr, 23.3, 100.2 ;Displays results at the terminal
To display the results in Galactic coordinates
IDL> xyad, hdr, 23.3, 100.2, /GALACTIC
PROCEDURES CALLED
ADSTRING(), EULER, EXTAST, GSSSXYAD, REPCHR(), XY2AD
REVISION HISTORY:
W. Landsman STX Jan, 1988
Use astrometry structure W. Landsman Jan, 1994
Recognize GSSS header W. Landsman June, 1994
Changed ADSTRING output format W. Landsman September 1995
Converted to IDL V5.0 W. Landsman September 1997
Use vector call to ADSTRING() W. Landsman February 2000
Added ALT input keyword W. Landsman June 2003
Add precision keyword W. Landsman February 2004
Fix display if 'RA','DEC' reversed in CTYPE W. Landsman Feb. 2004
Handle display of NaN values W. Landsman May 2004
Work for non-spherical coordinate transformations W. Landsman Oct 2004
Fix output display units if ALT keyword used W. Landsman March 2005
More informative error message if no astrometry present W.L Nov 2007
Fix display when no equinox in header W.L. Dec 2007
Fix header display for noncelestial coords W.L. Jan 2008
(See astrolib/pro/xyad.pro)
XYXY
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NAME:
XYXY
PURPOSE:
To use a pair of headers to convert X/Y positions from one frame
to another.
CALLING SEQUENCE:
XYXY, hdra, hdrb, xa, ya, [ xb, yb ]
INPUTS:
hdra - The header containing the plate solution describing the
frame of reference being converted FROM.
hdra - The header containing the plate solution describing the
frame of reference being converted TO.
xa - A scalar or vector containing the x coordinate(s) to convert.
ya - A scalar or vector containing the y coordinate(s) to convert.
Must have the same number of elements as 'xa'.
OUTPUTS:
xb - The converted x coordinate(s). If this parameter is not
specified, it is returned through 'xa'.
yb - The converted y coordinate(s). If this parameter is not
specified, it is returned through 'ya'.
PROCEDURE:
The procedures 'xyad' and 'adxy' are used to perform the
conversion. The equinoxes of each header are checked with
"get_equinox" to make sure that they are identical, and "precess"
is used if they are not. HEULER used if the headers have a different
coordinate system (e.g. Celestial, Galactic, Ecliptic)
Note that all X,Y coordinates are in the IDL convention (starting with
0,0) and not the FITS convention (first pixel is 1,1)
PROCEDURES USED:
GET_EQUINOX(), EXTAST, XYAD, ADXY, PRECESS, HEULER
MODIFICATION HISTORY:
Written by Michael R. Greason, Hughes-STX, 13 April 1992.
Updated to use ASTROMETRY structures. J.D.Offenberg, HSTX, Jan 1993
Converted to IDL V5.0 W. Landsman September 1997
Check coordinate system J. Ballet/ W. Landsman April 2004
(See astrolib/pro/xyxy.pro)
XYZ
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NAME:
XYZ
PURPOSE:
Calculate geocentric X,Y, and Z and velocity coordinates of the Sun
EXPLANATION:
Calculates geocentric X,Y, and Z vectors and velocity coordinates
(dx, dy and dz) of the Sun. (The positive X axis is directed towards
the equinox, the y-axis, towards the point on the equator at right
ascension 6h, and the z axis toward the north pole of the equator).
Typical position accuracy is <1e-4 AU (15000 km).
CALLING SEQUENCE:
XYZ, date, x, y, z, [ xvel, yvel, zvel, EQUINOX = ]
INPUT:
date: reduced julian date (=JD - 2400000), scalar or vector
OUTPUT:
x,y,z: scalars or vectors giving heliocentric rectangular coordinates
(in A.U) for each date supplied. Note that sqrt(x^2 + y^2
+ z^2) gives the Earth-Sun distance for the given date.
xvel, yvel, zvel: velocity vectors corresponding to X, Y and Z.
OPTIONAL KEYWORD INPUT:
EQUINOX: equinox of output. Default is 1950.
EXAMPLE:
What were the rectangular coordinates and velocities of the Sun on
Jan 22, 1999 0h UT (= JD 2451200.5) in J2000 coords? NOTE:
Astronomical Almanac (AA) is in TDT, so add 64 seconds to
UT to convert.
IDL> xyz,51200.5+64.d/86400.d,x,y,z,xv,yv,zv,equinox = 2000
Compare to Astronomical Almanac (1999 page C20)
X (AU) Y (AU) Z (AU)
XYZ: 0.51456871 -0.76963263 -0.33376880
AA: 0.51453130 -0.7697110 -0.3337152
abs(err): 0.00003739 0.00007839 0.00005360
abs(err)
(km): 5609 11759 8040
NOTE: Velocities in AA are for Earth/Moon barycenter
(a very minor offset) see AA 1999 page E3
X VEL (AU/DAY) YVEL (AU/DAY) Z VEL (AU/DAY)
XYZ: -0.014947268 -0.0083148382 -0.0036068577
AA: -0.01494574 -0.00831185 -0.00360365
abs(err): 0.000001583 0.0000029886 0.0000032077
abs(err)
(km/sec): 0.00265 0.00519 0.00557
PROCEDURE CALLS:
PRECESS_XYZ
REVISION HISTORY
Original algorithm from Almanac for Computers, Doggett et al. USNO 1978
Adapted from the book Astronomical Photometry by A. Henden
Written W. Landsman STX June 1989
Correct error in X coefficient W. Landsman HSTX January 1995
Added velocities, more terms to positions and EQUINOX keyword,
some minor adjustments to calculations
P. Plait/ACC March 24, 1999
(See astrolib/pro/xyz.pro)
YDN2MD
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NAME:
YDN2MD
PURPOSE:
Convert from year and day number of year to month and day of month.
CALLING SEQUENCE:
YDN2MD,yr,dy,m,d
INPUTS:
yr = 4 digit year (like 1988), integer scalar
dy = day number in year (like 310), integer scalar or vector
OUTPUTS:
m = month number (1-12, e.g. 11 = Nov)
d = day of month (like 5).
Note: On error returns m = d = -1.
EXAMPLE:
Find the month/day of days 155 and 255 in the year 2001
IDL> ydn2md, 2001, [155,255], m, d
==> m = [6,9] & d = [4,12] ; = June 4 and September 12
MODIFICATION HISTORY:
Adapted from Johns Hopkins University/Applied Physics Laboratory
Update to use VALUE_LOCATE, W. Landsman January 2001
(See astrolib/pro/ydn2md.pro)
ZANG
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NAME:
ZANG
PURPOSE:
Determine the angular size of an object as a function of redshift
EXPLANATION:
Requires an input size in kpc and returns an angular size in arc seconds
Default cosmology has a Hubble constant of 70 km/s/Mpc, Omega (matter)
=0.3 and a normalized cosmological constant Lambda = 0.7; however these
values can be changed with appropriate keywords.
CALLING SEQUENCE:
angsiz = zang( dl, [ z, H0 =, Omega_m =, Lambda0 = , q0 = , k =,
/SILENT] )
INPUTS:
dl - linear size of the object *in kpc*, non-negative scalar or vector
z - redshift of object, postive scalar or vector
Either dl and z must have the same number of elements, or at least
one of them must be a vector.
OPTIONAL INPUT KEYWORDS
H0 - Hubble constant in km/s/Mpc, default is 70
No more than two of the following four parameters should be
specified. None of them need be specified, default values are given
k - curvature constant, normalized to the closure density. Default is
0, indicating a flat universe
Omega_m - Matter density, normalized to the closure density, default
is 0.3. Must be non-negative
Lambda0 - Cosmological constant, normalized to the closure density,
default is 0.7
q0 - Deceleration parameter, numeric scalar = -R*(R'')/(R')^2, default
is -0.55
Note that Omega_m + lambda0 + k = 1 and q0 = 0.5*omega_m - lambda0
OUTPUT:
angsiz - Angular size of the object at the given redshift in
arc seconds
EXAMPLE:
(1) What would be the angular size of galaxy of diameter 50 kpc at a redshift
of 1.5 in an open universe with Lambda = 0 and Omega (matter) = 0.3.
Assume the default Hubble constant value of 70 km/s/Mpc.
IDL> print,zang(50,1.5, Lambda = 0,omega_m = 0.3)
====> 6.58 arc seconds
(2) Now plot the angular size of a 50 kpc diameter galaxy as a function of
redshift for the default cosmology (Lambda = 0.7, Omega_m=0.3) up to
z = 0.5
IDL> z = findgen(50)/10. + 0.1 ;Angular size undefined at z = 0
IDL> plot,z,zang(50,z),xtit='z',ytit='Angular Size (")'
NOTES:
This procedure underwent a major revision in April 2000 to allow for a
cosmological constant, ***including a change of the calling sequence***
Be sure to supply the input linear size dl in units of kpc.
PROCEDURES CALLED:
LUMDIST() -- Calculates the luminosity distance
REVISION HISTORY:
Written J. Hill STX July, 1988
Converted to IDL V5.0 W. Landsman September 1997
Major rewrite to call LUMDIST function W. Landsman April 2000
(See astrolib/pro/zang.pro)
ZBRENT
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NAME:
ZBRENT
PURPOSE:
Find the zero of a 1-D function up to specified tolerance.
EXPLANTION:
This routine assumes that the function is known to have a zero.
Adapted from procedure of the same name in "Numerical Recipes" by
Press et al. (1992), Section 9.3
CALLING:
x_zero = ZBRENT( x1, x2, FUNC_NAME="name", MaX_Iter=, Tolerance=,
_EXTRA = )
INPUTS:
x1, x2 = scalars, 2 points which bracket location of function zero,
that is, F(x1) < 0 < F(x2).
Note: computations are performed with
same precision (single/double) as the inputs and user supplied function.
REQUIRED INPUT KEYWORD:
FUNC_NAME = function name (string)
Calling mechanism should be: F = func_name( px )
where: px = scalar independent variable, input.
F = scalar value of function at px,
should be same precision (single/double) as input.
OPTIONAL INPUT KEYWORDS:
MAX_ITER = maximum allowed number iterations, default=100.
TOLERANCE = desired accuracy of minimum location, default = 1.e-3.
Any other keywords are passed directly to the user-supplied function
via the _EXTRA facility.
OUTPUTS:
Returns the location of zero, with accuracy of specified tolerance.
PROCEDURE:
Brent's method to find zero of a function by using bracketing,
bisection, and inverse quadratic interpolation,
EXAMPLE:
Find the root of the COSINE function between 1. and 2. radians
IDL> print, zbrent( 1, 2, FUNC = 'COS')
and the result will be !PI/2 within the specified tolerance
MODIFICATION HISTORY:
Written, Frank Varosi NASA/GSFC 1992.
FV.1994, mod to check for single/double prec. and set zeps accordingly.
Use MACHAR() to define machine precision W. Landsman September 2002
Added _EXTRA keyword W. Landsman December 2011
Need to check whether user function accepts keywords W.L. Jan 2012
(See astrolib/pro/zbrent.pro)
ZENPOS
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NAME:
ZENPOS
PURPOSE:
Return the zenith RA and Dec in radians for a given Julian date.
CALLING SEQUENCE:
ZENPOS, Date, Ra, Dec
INPUT:
Date The Julian date, in double precision, of the date and time
for which the zenith position is desired, scalar or vector.
OUTPUTS:
Ra The right ascension in RADIANS of the zenith.
Dec The declination in RADIANS of the zenith.
PROCEDURE:
The local sidereal time is computed; this is the RA of the zenith.
It and the observatories latitude (corresponding to the Dec.) are
converted to radians and returned as the zenith direction.
PROMPTS:
ZENPOS will prompt for the following 3 parameters if they are not
defined in the common block SITE (see below)
LAT,LNG - north latitude and east longitude of the desired location
in DEGREES
TZONE - Time Zone (in hours) of the desired location (e.g. 4 = EDT,
5 = EST)
COMMON BLOCKS:
SITE - This common block should contain the three scalars LAT, LNG
and TZONE
PROCEDURE CALLS:
CT2LST - Convert to Local Mean Sidereal Time
MODIFICATION HISTORY:
Written by Michael R. Greason, STX, 14 October 1988.
Converted to IDL V5.0 W. Landsman September 1997
Update documentation, longitude now *east* of Greenwich W.L. July 2000
(See astrolib/pro/zenpos.pro)
ZOOM_XY
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NAME:
ZOOM_XY
PURPOSE:
Converts X, Y position on the image array to the the X,Y position
in the current window. (These positions are identical
only for an unroamed, zoomed image with with pixel (0,0) of the
image placed at position (0,0) on the TV.)
CALLING SEQUENCE:
ZOOM_XY, Xim,Yim,Xtv,Ytv, [ OFFSET =, ZOOM = ]
INPUTS:
XIM - Scalar or vector giving X position(s) as read on the image
display (e.g. with CURSOR,XIM,YIM,/DEVICE)
YIM - Like XTV but giving Y position(s) as read on the image display.
If only 2 parameters are supplied then XIM and YIM will be modfied
on output to contain the converted coordinates.
OPTIONAL KEYWORD INPUT:
OFFSET - 2 element vector giving the location of the image pixel (0,0)
on the window display. OFFSET can be positive (e.g if the
image is centered in a larger window) or negative (e.g. if the
only the central region of an image much larger than the window
is being displayed.
Default value is [0,0], or no offset.
ZOOM - Scalar specifying the magnification of the window with respect
to the image variable.
OUTPUTS:
XTV,YTV - REAL*4 X and Y coordinates of the image corresponding to the
cursor position on the TV display. Same number of elements as
XIM, YIM.
COMMON BLOCKS:
If present, ZOOM_XY will use the TV and IMAGE common blocks which are
defined in the MOUSSE software system (see
http://archive.stsci.edu/uit/analysis.html) If the user is not using
the MOUSSE software (which keeps track of the offset and zoom in each
window) then the common blocks are ignored.
NOTES:
The integer value of a pixel is assumed to refer to the *center*
of a pixel.
REVISON HISTORY:
Adapted from MOUSSE procedure of the same name W. Landsman HSTX Mar 1996
Converted to IDL V5.0 W. Landsman September 1997
Properly include ZOOM keyword W. Landsman May 2000
Put back common blocks for MOUSSE compatibility September 2004
(See astrolib/pro/zoom_xy.pro)
ZPARCHECK
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NAME:
ZPARCHECK
PURPOSE:
Routine to check user parameters to a procedure
CALLING SEQUENCE:
zparcheck, progname, parameter, parnum, types, dimens, [ message ]
INPUTS:
progname - scalar string name of calling procedure
parameter - parameter passed to the routine
parnum - integer parameter number
types - integer scalar or vector of valid types
1 - byte 2 - integer 3 - int*4
4 - real*4 5 - real*8 6 - complex
7 - string 8 - structure 9 - double complex
10 - pointer 11 - object ref 12 - Unsigned integer
13 - unsigned int*4
14 - int*8
15 - Unsigned int*8
dimens - integer scalar or vector giving number
of allowed dimensions.
OPTIONAL INPUT:
message - string message describing the parameter to be printed if an
error is found
OUTPUTS:
none
EXAMPLE:
IDL> zparcheck, 'HREBIN', hdr, 2, 7, 1, 'FITS Image Header'
This example checks whether the parameter 'hdr' is of type string (=7)
and is a vector (1 dimension). If either of these tests fail, a
message will be printed
"Parameter 2 (FITS Image Header) is undefined"
"Valid dimensions are 1"
"Valid types are string"
SIDE EFFECTS:
If an error in the parameter is a message is printed
a RETALL issued
HISTORY
version 1 D. Lindler Dec. 86
documentation updated. M. Greason, May 1990.
Recognize double complex datatype W. Landsman September 1995
Converted to IDL V5.0 W. Landsman September 1997
Check for new data types (e.g. unsigned) W. Landsman February 2000
Print a traceback if an error occurs W. Landsman Aug 2011
(See astrolib/pro/zparcheck.pro)