QUERYGSC
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