This page is a listing of the entire contents of this library for IDL. This listing is the long version. Viewing the much more compact listing may be handier.
NAME:
ABSCAL
PURPOSE:
Apply the FITS BZERO and BSCALE keyword values to a data array
CALLING SEQUENCE:
RESULT = ABSCAL( Value, Header, /DEBUG)
INPUTS:
VALUE - Any scalar, vector, or array (usually an integer type giving a
relative intensity).
HEADER - A FITS header array containing the absolute calibration
keyword BSCALE, and optionally BZERO and BUNIT.
OUTPUT:
RESULT = BSCALE*VALUE + BZERO, where the BSCALE and BZERO scalars
are taken from the FITS header.
If the absolute calibration keywords do not exist, then
RESULT = VALUE, and !ERR = -1.
OPTIONAL INPUT KEYWORD:
/DEBUG - If DEBUG is set, then ABSCAL will print the
calibration units given by the BUNIT keyword.
REVISION HISTORY:
Written W. Landsman, STX Corporation January 1987
Use DEBUG keyword instead of !DEBUG September 1995
Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/abscal.pro)
NAME:
AD2XY
PURPOSE:
Compute X and Y from RA and DEC and a FITS astrometry structure
EXPLANATION:
A tangent (gnomonic) projection is computed directly; other projections
are computed using WCSXY2SPH. AD2XY is 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. in DEGREES, scalar or vector
D - Dec. 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 R.A. and DEC of reference pixel
in DEGREES
.CTYPE - 2 element vector giving projection types
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)
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
Converted to IDL V5.0 W. Landsman September 1997
Understand reversed X,Y (X-Dec, Y-RA) axes, W. Landsman October 1998
(See /host/bluemoon/usr2/idllib/astron/pro/ad2xy.pro)
NAME:
ADSTRING
PURPOSE:
Return RA and Dec as character string in sexigesimal 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 )
or
result = ADSTRING( ra,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
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]. It is not available
for just DEC. If no PRECISION parameter is passed, a
precision of 1 for both RA and DEC is returned to maintain
compatibility with past ADSTRING functions. 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.
OUTPUT:
RESULT - Character string 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 sexigesimal 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 sexigesimal 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:
FSTRING(), 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]
Converted to IDL V5.0 W. Landsman 24-Nov-1997
Major rewrite to allow vector inputs W. Landsman February 2000
(See /host/bluemoon/usr2/idllib/astron/pro/adstring.pro)
NAME:
ADXY
PURPOSE:
Use a FITS header to convert celestial (RA,Dec) to pixel coordinates
EXPLANATION:
Use an image header to compute X and Y positions, given the
RA and Dec in decimal degrees.
CALLING SEQUENCE:
ADXY, HDR ;Prompt for Ra and DEC
ADXY, hdr, a, d, x, y, [ /PRINT ]
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).
OPTIONAL KEYWORD INPUT:
/PRINT - If this keyword is set and non-zero, then results are displayed
at the terminal.
OPERATIONAL NOTES:
If less than 5 parameters are supplied, or if the /PRINT keyword is
set, then 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()
REVISION HISTORY:
W. Landsman HSTX January, 1988
Use astrometry structure W. Landsman January, 1994
Changed default ADSTRING format W. Landsman September, 1995
Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/adxy.pro)
NAME:
AFhread
PURPOSE:
Subroutine of WFPCREAD to read a GEIS header from an HST STSDAS image.
EXPLANATION:
This procedure reads a GEIS header from an HST image. It then looks
if a .SHH file is present for FOC images to calculate better
astrometry by getting the current PSANGLV3 from this file. Called by
WFPCREAD.PRO
CALLING SEQUENCE:
AFhread, HdrFile, hdr
INPUTS:
HdrFile - scalar string giving name of STSDAS header for an FOC image
OUTPUTS:
hdr - string array, FITS header for the FOC image. The position
angle of the V3 axis of HST (PSANGLV3) is added, if it could
be found in the .SHH file
PROCEDURE CALLS:
STRN(), SXADDPAR, SXHREAD, SXPAR()
REVISION HISTORY:
Written Eric W. Deutsch (U. of Washington) June, 1994
Documentation update W. Landsman (HSTX) July, 1994
Converted to IDL V5.0 W. Landsman September 1997
Removed call to EXIST() function W. Landsman April 1999
(See /host/bluemoon/usr2/idllib/astron/pro/afhread.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 the IAU standard for conversion given in Morton
(1991 Ap.J. Suppl. 77, 119)
CALLING SEQUENCE:
AIRTOVAC, WAVE
INPUT/OUTPUT:
WAVE - Wavelength in Angstroms, scalar or vector
WAVE should be input as air wavelength(s), it will be
returned as vacuum wavelength(s). WAVE is always converted to
double precision upon return.
EXAMPLE:
If the air wavelength is W = 6056.125 (a Krypton line), then
AIRTOVAC, W yields an vacuum wavelength of W = 6057.8019
METHOD:
See Morton (Ap. J. Suppl. 77, 119) for the formula used
REVISION HISTORY
Written W. Landsman November 1991
Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/airtovac.pro)
NAME:
AITOFF
PURPOSE:
Convert Right Ascension, Declination 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 /host/bluemoon/usr2/idllib/astron/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,[LINESTYLE=N, LABEL =, /NEW ]
OPTIONAL 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.
OPTIONAL INPUT KEYWORDS:
LINESTYLE = Optional input integer specifying the linestyle to
use for drawing the grid lines.
LABEL = 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.
/NEW = If this keyword is set, then AITOFF_GRID will create
a new plot grid, rather than overlay an existing plot.
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
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
(See /host/bluemoon/usr2/idllib/astron/pro/aitoff_grid.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, /EXACT, /FLUX, PRINT = , /SILENT, 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
BADPIX - Two element vector giving the minimum and maximum value
of a good pix (Default [-32765,32767])
OPTIONAL KEYWORD INPUTS:
/EXACT - By default, APER counts subpixels, but uses a polygon
approximation for the intersection of a circular aperture with
a square pixel (and normalize 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.
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'.
/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). A flux of 1 digital unit is assigned
a zero point magnitude of 25.
ERRAP - NAPER by NSTAR array giving error in magnitude
for each star. If a magnitude could not be deter-
mined then ERRAP = 9.99.
SKY - NSTAR element vector giving sky value for each star
SKYERR - NSTAR element vector giving error in sky values
PROCEDURES USED:
DATATYPE(), 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
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
Adapted for IDL Version 2, J. Isensee, July, 1990
Code, documentation spiffed up W. Landsman August 1991
TEXTOUT may be a string W. Landsman September 1995
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
Converted to IDL V5.0 W. Landsman September 1997
Don't abort for insufficient sky pixels W. Landsman May 2000
Added /EXACT keyword W. Landsman June 2000
(See /host/bluemoon/usr2/idllib/astron/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= ]
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 - integer scalar specifying the color to draw the arcbar (using
PLOTS), default = !P.COLOR
/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
SIZE - scalar specifying character size of label, default = 1.0
THICK - Character thickness of the label, default = !P.THICK
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()
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
Converted to IDL V5.0 W. Landsman September 1997
Added /DATA, /SECONDS keywords W. Landsman July 1998
(See /host/bluemoon/usr2/idllib/astron/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 or STSDAS 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 that the arrows and NE letters should be. Default
value is !P.COLOR
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:
EXTAST - Extract astrometry structure from 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
Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/arrows.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 Ascention 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 sexigesimal 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 /host/bluemoon/usr2/idllib/astron/pro/astdisp.pro)
NAME: ASTRMFIX PURPOSE: Calculate a rough HST WFPC or FOC astrometry solution EXPLANATION: This program will calculate a rough HST WFPC or FOC astrometry solution using the keyword PSANGLEV3 which gives the angle of the V3 axis of HST. Called by WFPCREAD. CALLING SEQUENCE: AstrmFix, hdr, chip INPUT - OUTPUT: hdr - FITS header (string array) from either WFPC or FOC. Header will be updated with rough astrometry INPUT: chip - Scalar (typically 0-3) giving the WFPC chip to read. HISTORY: ??-???-???? Written by Eric W. Deutsch 22-OCT-1992 Changed all calculations to double precision. (E. Deutsch) 22-OCT-1992 Updated PC Pixel size of 0.04389 from WFPC IDT OV/SV manual(EWD) 22-OCT-1992 Updated WF Pixel size of 0.1016 from WFPC IDT OV/SV manual(EWD) 11-JAN-1993 Added warning message and changed CD001001... to CD1_1... (EWD) Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/astrmfix.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 /host/bluemoon/usr2/idllib/astron/pro/astro.pro)
NAME:
ASTROLIB
PURPOSE:
Add the non-standard system variables used by the IDL Astronomy Library
EXPLANATION:
Also defines the environment variable or VMS
logical ASTRO_DATA pointing to the directory containing data files
associated with the IDL Astronomy library (system dependent).
CALLING SEQUENCE:
ASTROLIB
INPUTS:
None.
OUTPUTS:
None.
METHOD:
The non-standard system variables !PRIV, !DEBUG, !TEXTUNIT, and
!TEXTOUT are added using DEFSYSV.
REVISION HISTORY:
Written, Wayne Landsman, July 1986.
Use DEFSYSV instead of ADDSYSVAR December 1990
Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/astrolib.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.
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, 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; otherwise,
the result is floating-point. Use of the /DOUBLE keyword
forces a double precision output -- this is equivalent to (but
faster than) first converting the input array to double.
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)/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
(See /host/bluemoon/usr2/idllib/astron/pro/avg.pro)
NAME:
A_b
PURPOSE:
Compute B band interstellar extinction according to the RC2.
EXPLANATION:
The predicted B band extinction is computed as a function of
Galactic position using the 21 parameter function given by
deVaucouleurs in the 2nd Reference Catalog of Galaxies (RC2). Note
that this formula is no longer used in the RC3 and that reddenings
are instead obtained from the Burstein-Heiles 21 cm maps.
CALLING SEQUENCE:
result = A_b( l2, b2)
INPUT PARAMETERS
l2 = Galactic longitude (degrees), scalar or vector
b2 = Galactic latitude (degrees), scalar or vector
OUTPUT PARAMETERS
RESULT - Interstellar extinction Ab in magnitudes, same number of
elements as input l2 and b2 parameters
NOTES:
The controversial aspect of the deVaucouleurs reddening curve
is that it predicts an extinction of about 0.2 at the poles
The parameters used here differ from the ones printed in the RC2
but are the ones actually used for entries in the catalog
(see Rowan-Robinson 1985)
This procedure is mainly of historical interest only, and reddening
is now better determined using dust maps, such as those available at
http://astro.berkeley.edu/davis/dust/index.html
REVISION HISTORY
Written by R. Cornett and W. Landsman, STX October 1987
Vectorized code W. Landsman STX December 1992
Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/a_b.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
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.
PROCEDURE CALLED:
Function PREMAT() -- computes precession matrix
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
EXAMPLE:
Compute the radial velocity of the Earth toward Altair on 15-Feb-1994
IDL> jdcnv, 1994, 2, 15, 0, jd ;==> JD = 2449398.5
IDL> baryvel, jd, 2000, vh, vb
==> vh = [-17.07809, -22.80063, -9.885281] ;Heliocentric km/s
==> vb = [-17.08083, -22.80471, -9.886582] ;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
(See /host/bluemoon/usr2/idllib/astron/pro/baryvel.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 /host/bluemoon/usr2/idllib/astron/pro/blink.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 accomodate 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. CATEGOBY: 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 /host/bluemoon/usr2/idllib/astron/pro/boost_array.pro)
NAME:
BOXAVE
PURPOSE:
Box-average a 1 or 2 dimensional array. 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
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
(See /host/bluemoon/usr2/idllib/astron/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 1.5", 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 available at ned.ipac.caltech.edu 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
Converted to IDL V5.0 W. Landsman September 1997
Fixed bug where A term not initialized for vector input
W. Landsman February 2000
(See /host/bluemoon/usr2/idllib/astron/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. (In
VMS the $ can either be part of the path, or can signal logical
names for compatibility with Unix.) 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:
Functions: DATATYPE(), STR_SEP()
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
Converted to IDL V5.0 W. Landsman 25-Nov-1997
Fix directory character on Macintosh system A. Ferro February 2000
(See /host/bluemoon/usr2/idllib/astron/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)
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 /host/bluemoon/usr2/idllib/astron/pro/bsort.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.
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 /host/bluemoon/usr2/idllib/astron/pro/ccm_unred.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 or STSDAS 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 HDR contains a DATATYPE keyword (as in STSDAS headers), then this is
also checked against the datatype of of IM
If the /UPDATE keyword is present, then FITS header will be modified, if
necessary, to force agreement with the image array
CALLING SEQUENCE:
check_FITS, im, hdr, [ dimen, idltype, /UPDATE, /NOTYPE, /SDAS, /SILENT
ERRMSG = ]'
INPUT PARAMETERS:
IM - FITS (or STSDAS) array, e.g. as read by READFITS
HDR - FITS (or STSDAS) 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 DATATYPE
FITS keywords will be updated to agree with the array
/SDAS - If this keyword is set then the header is assumed to be from
an SDAS (.hhh) file. CHECK_FITS will then ensure that (1)
a DATATYPE keyword is included in the header and (2) BITPIX
is always written with positive values.
/FITS - If this keyword is present then CHECK_FITS assumes that it is
dealing with a FITS header and not an SDAS header, see notes
below.
/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.
SYSTEM VARIABLE:
For consistency with previous versions, CHECK_FITS sets the obsolete
!ERR keyword, although its use is discouraged in favor of the ERRMSG
keyword. If there is a fatal problem with the FITS array or header
then !ERR is set to -1. ( If the UPDATE keyword was supplied, and the
header could be fixed, then !ERR = 0.)
PROCEDURE:
Program checks the NAXIS1 and NAXIS2 parameters in the header to
see if they match the image array dimensions.
NOTES:
An important distinction between an STSDAS header and a FITS header
is that the BITPIX value in an STSDAS header is always positive,
e.g. BITPIX=32 for REAL*4 data. Users should use either the /SDAS
or the /FITS keyword if it is important whether the STSDAS or FITS
convention for REAL*4 data is used. Otherwise, CHECK_FITS assumes
that if a DATATYPE keyword is present then it is dealing with an
STSDAS header.
PROCEDURE CALLS:
STRN(),FXADDPAR, fxpar()
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
(See /host/bluemoon/usr2/idllib/astron/pro/check_fits.pro)
NAME : CHECK_TAPE_DRV PURPOSE : Associates tape drive numbers with device files. *Unix only* EXPLANATION : This is an internal routine to the CDS/SERTS Unix tape handling utilities. It converts tape drive numbers to actual device names, and checks to make sure that the device file is open. **Unix only** CALLING SEQUENCE: : CHECK_TAPE_DRV, UNIT, LOGICAL_DRIVE, DRIVE, LUN INPUTS UNIT = Tape unit number. Tape drives are selected via the UNIX environment variables "MT1", "MT2", etc. The desired tape drive is thus specified by numbers, as in VMS. Must be from 0 to 9. OUTPUTS : LOGICAL_DRIVE = Name of environment variable pointing to tape drive device file, e.g. "MT0". DRIVE = Name of device file, e.g. '/dev/nrst0'. LUN = Logical unit number used for reads and writes. COMMON : CHCK_TAPE_DRVS contains array TAPE_LUN, containing logical unit numbers for each tape device, and TAPE_OPEN, which tells whether each device is open or not. RESTRICTIONS: The environment variable "MTn", where n corresponds to the variable UNIT, must be defined. E.g., setenv MT0 /dev/nrst0 Requires IDL v3.0 or later. SIDE EFFECTS: If the device file is not yet open, then the tape is rewound, and a file unit is opened to it. Category : Utilities, I/O, Tape. Prev. Hist. : William Thompson, Apr 1991. Written : William Thompson, GSFC, April 1991. Modified : Version 1, William Thompson, GSFC, 21 December 1993. Added keyword /NOSTDIO to OPEN statement. Incorporated into CDS library. Version 2, William Thompson, GSFC, 22 December 1993. Added spawn to "mt rewind". Version 3, W. Landsman GSFC 10-Apr-1996 Open for Readonly, if Update access is unavailable Version : Version 3, 10-Apr-1996. Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/check_tape_drv.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 /host/bluemoon/usr2/idllib/astron/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, Hughex STX, May 1996
Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/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]
INPUTS:
None
OPTIONAL KEYWORD INPUT:
/SILENT - If set, then CLEANPLOT will not display a message giving the
the system variables tags being reset.
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 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
(See /host/bluemoon/usr2/idllib/astron/pro/cleanplot.pro)
NAME:
CNTRD
PURPOSE:
Compute the centroid coordinates of a stellar object
using the algorithm in the DAOPHOT FIND subroutine.
CALLING SEQUENCE:
CNTRD, img, x, y, xcen, ycen, [ fwhm , /SILENT, /DEBUG]
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. 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
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.
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.
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
(See /host/bluemoon/usr2/idllib/astron/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 be different struct.defs.), and return a structured List of fields found different. CATEGORY: Structures CALLING SEQUENCE: diff_List = compare_struct( struct_A, struct_B ) INPUTS: struct_A, struct_B : the two structure arrays to compare. Struct_Name : for internal recursion use only. 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. /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. PROCEDURE: Match Tag names and then use where function on tags. 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. Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/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> f = concat_dir(dir,file)
RESTRICTIONS:
Assumes Unix type format if os is not vms, MacOS or Windows.
The version of CONCAT_DIR available at
http://sohowww.nascom.nasa.gov/solarsoft/gen/idl/system/concat_dir.pro
includes 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
(See /host/bluemoon/usr2/idllib/astron/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 tangent projection
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, CD, 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 and SIN 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 (2000, A&A, in press).
These documents are available from
http://fits.cv.nrao.edu/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
(See /host/bluemoon/usr2/idllib/astron/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
(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 Greisen & Calabretta (2000, A&A, in press).
These documents are available from
http://fits.cv.nrao.edu/documents/wcs/wcs.html
RESTRICTIONS:
Implemented only for the TANgent and SIN projections
REVISION HISTORY:
Written, Wayne Landsman STX Co. April, 1988
Algorithm adapted from AIPS memo No. 27 by Eric Griessen
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
(See /host/bluemoon/usr2/idllib/astron/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). 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). 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) METHOD: When using FFT, PSF is centered & expanded to size of image. HISTORY: written, Frank Varosi, NASA/GSFC 1992. Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/convolve.pro)
NAME: CONV_STSDAS PURPOSE: Convert internal format of an STSDAS image to host machine architecture EXPLANATION: Converts the internal format of an STSDAS image (.hhh and .hhd file) to the host machine architecture. Useful for copying STSDAS files between different machines. If the host is not a VMS machine, then by default CONV_STSDAS assumes the image originated on VMS. If the host is VMS, then CONV_STSDAS assumes that the image originated on an IEEE machine (e.g. SparcStation). CALLING SEQUENCE: CONV_STSDAS, sdas_name, [ /FROM_IEEE] INPUTS: sdas_name - scalar string giving name of the STSDAS image CONV_STSDAS assumes a default header extension of .hhh -- otherwise the header extension should be included in sdas_name. The internal format of the file will be modified by CONV_STSDAS. OPTIONAL KEYWORD INPUT: /FROM_IEEE - On little endian machines (OSF, windows) this keyword indicates that the STSDAS file originated on an IEEE machine (e.g SparcStation) rather than a VMS machine EXAMPLE: Suppose files test.hhd and test.hhh have been copied with FTP from a Vax to a Sparcstation. Convert these files to the SparcStation internal format. IDL> conv_stsdas, 'test' METHOD: CONV_STSDAS reads each group image and parameter block and uses IEEE_TO_HOST or CONV_VAX_UNIX to convert the internal format. The converted images and parameter blocks are written back to the orginal file. PROCEDURE CALLS sxopen, fdecomp, datatype(), sxgpar(), ieee_to_host, conv_vax_unix() NOTES: (1) When copying STSDAS files to VMS, be sure the .hhh file is formatted as fixed block 80 byte. (2) CONV_STSDAS has no way of knowing if a file really came from a different machine architecture. If it is applied to a file that already has the correct internal format, then CONV_STSDAS will "convert" this file and corrupt the internal format. (3) Note that CONV_STSDAS currently does not support conversion *from* a little-endian machine (OSF, windows) REVISION HISTORY: Written W. Landsman January, 1993 Don't require .hhh extension April, 1993 Increase speed by calling SXGINFO May, 1993 Converted to IDL V5.0 W. Landsman September 1997
(See /host/bluemoon/usr2/idllib/astron/pro/conv_stsdas.pro)
NAME:
CONV_UNIX_VAX
PURPOSE:
To convert Unix IDL data types to Vax IDL data types.
EXPLANATION:
CONV_UNIX_VAX assumes the Unix IDL data type is IEEE standard in either
big-endian or little-endian format.
CALLING SEQUENCE:
CONV_UNIX_VAX, variable, [ SOURCE_ARCH = ]
PARAMETERS:
variable - The data variable to be converted. This may be a scalar
or an array. Valid datatypes are integer, longword,
floating point, and double precision. The result of the
conversion is passed back in the original variable.
OPTIONAL INPUT KEYWORD:
SOURCE_ARCH = name (string) of source architecture
if using this function on a VAX, otherwise
!VERSION.ARCH is used to determine the conversion.
**If run on a VAX, the default is to assume the source to be
a little-endian machine with IEEE floating point
(e.g. MIPSEL or Alpha***).
RESTRICTIONS:
Requires that data be from IEEE standard Unix machines
(e.g. SUN, MIPSEL, or Alpha).
EXAMPLE:
Read a 100 by 100 matrix of floating point numbers from a data
file created on a Sun. Then convert the matrix values into
VAX format.
IDL> openr,1,'vax_float.dat
IDL> data = fltarr(100,100)
IDL> forrd,1,data
IDL> CONV_UNIX_VAX,data,SOURCE_ARCH='sparc'
MODIFICATION HISTORY:
Version 1 By John Hoegy 13-Jun-88
04-May-90 - WTT: Created CONV_UNIX_VAX from VAX2SUN,
reversing floating point procedure.
Modified P. Keegstra September 1994
Implemented MIPSEL and ALPHA architecture,
distinguishing VMS and OSF
Modified P. Keegstra February 1995
Added 386 PC based architectures
If since V5.1 then VMS is always little endian June 1998
Convert to IDL V5.0 W. Landsman June 1998
(See /host/bluemoon/usr2/idllib/astron/pro/conv_unix_vax.pro)
NAME:
CONV_VAX_UNIX
PURPOSE:
To convert VAX IDL data types to UNIX (Sun,MIPS,etc.) IDL data types.
EXPLANTION:
Generally used on non-Vax machines to parse data created on Vaxes.
The architecture is obtained from IDL sys.var. !VERSION.ARCH.
CALLING SEQUENCE:
var_unix = conv_vax_unix( var_vax, [TARGET_ARCH = ] )
INPUT PARAMETER:
var_vax - The data variable to be converted. This may be a scalar
or an array. All IDL datatypes are valid (including
structures). The result of the conversion is returned by the
function.
OPTIONAL INPUT KEYWORD:
TARGET_ARCH = name (string) of desired target architecture
(e.g. 'sparc' or 'mipsel'). If not supplied, then
!VERSION.ARCH is used to determine the target architecture.
Note that CONV_VAX_UNIX will leave variables unchanged on a
VMS machine, unless the TARGET_ARCH keyword is set.
EXAMPLE:
Read a 100 by 100 matrix of floating point numbers from a data
file created on a VAX. Then convert the matrix values into Sun format.
IDL> openr,1,'vax_float.dat'
IDL> data = fltarr(100,100)
IDL> readu,1,data
IDL> data = conv_vax_unix( data )
NOTE:
Prior to IDL V5.1, the architecture "alpha" was ambiguous, since VMS
alpha IDL used VAX D-float while OSF/1 alpha IDL uses little-endian
IEEE. The program uses !VERSION.OS to do the right thing when
converting to a representation appropriate for the current
platform. To convert to a representation appropriate for
an OSF/1 alpha on a VAX or (pre V5.1) VMS alpha, please specify
the "mipsel" (or "i386") architecture.
MODIFICATION HISTORY:
Written F. Varosi August 1990
Modified P. Keegstra April 1992
Implemented MIPSEL architecture
Modified P. Keegstra July 1994
Implemented ALPHA architecture, distinguishing VMS and OSF
Modified P. Keegstra February 1995
Added 386 PC based architectures
Modified P. Keegstra March 1995
Added note, restored and fixed old specifiers
for 386 PC based architectures
Modified W. Landsman for VAX problems in V4.0 August 1995
Work for double complex variables August 1995
Remove informational messages under VMS August 1997
Since V5.1, IDL VMS uses little endian IEEE June 1998
Convert to IDL V5.0 June 1998
(See /host/bluemoon/usr2/idllib/astron/pro/conv_vax_unix.pro)
NAME: COPY_STRUCT PURPOSE: Copy all fields with matching tag names from one structure to another EXPLANATION 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
(See /host/bluemoon/usr2/idllib/astron/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
(See /host/bluemoon/usr2/idllib/astron/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
(See /host/bluemoon/usr2/idllib/astron/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 /host/bluemoon/usr2/idllib/astron/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 /host/bluemoon/usr2/idllib/astron/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 cosmolgical constant, Omega_lambda (2) 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 Caroll, 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 = -0.5
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 parmeter, 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
(See /host/bluemoon/usr2/idllib/astron/pro/cosmo_param.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)
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,
'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 /CHATTER is 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 /NODELETE is 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.
At present, can fail if a tag_name cannot be used as a proper
structure component definition, e.g., '0.10' will not
work, but a typical string like 'RA' or 'DEC' will.
A partial workaround checks for characters '\' and '/'
and '.' and converts them to '_'. in a tag_name.
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:
FDECOMP, GETTOK(), 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
Converted to IDL V5.0 W. Landsman September 1997
Write temporary file in HOME directory if necessary W. Landsman Jul 98
Use OPENR,/DELETE for OS-independent file removal W. Landsman Jan 99
(See /host/bluemoon/usr2/idllib/astron