IMDBASE
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