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IMDBASE

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
      Use V6.0 notation W. L. Aug 2013



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