IMDBASE

     Find the sources in an IDL database that are located on a given image.

    imdbase, hdr, catalogue, [list, ALT=, XPOS= ,YPOS=, XRANGE= ,YRANGE= ,
                       SUBLIST = ]

    hdr - FITS image header containing astrometry, and the NAXIS1,
               NAXIS2 keywords giving the image size
    catalogue - string giving name of catalogue in database
              Database must contain the (preferably indexed)
              fields RA (in hours) and DEC.   Type DBHELP for a
              list of the names of available catalogues.

    LIST - A long 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)

     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

       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.
     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.
     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.

     If an output list vector is not supplied, then the found objects are
     diplayed at the terminal.

      Find all existing IUE SWP observations within the field of the STSDAS
      disk file FUV0435FC.  Subselect those taken with the SWP camera
      SXHREAD,'fuv0435fc',H             ;Read header from disk
      IMDBASE,H,'IUE',list              ;Find IUE obs. within image
      LIST2 = DBFIND('CAM_NO=3',LIST)   ;Subselect on SWP images

      The IDL database is left open upon exiting IMDBASE.

      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.

      The non-standard system variable !TEXTOUT is required for use with the
      database procedures.

      AD2XY, DBEXT, DB_ITEM, DB_ITEM_INFO(), DBOPEN, DBFIND(), EXTAST,
      GET_EQUINOX(), GSSSADXY, GSSSXYAD, HPRECESS, SXPAR(), XY2AD

      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
      Converted to IDL V5.0   W. Landsman   September 1997
      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

[Home Page] [Software, Documentation] [IDL Documentation] [Quick Reference] [Feedback]