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    Query the digital sky survey (DSS) on-line at the STSCI (or ESO) server


    The script can query the DSS survey and retrieve an image and FITS
    header either from the the Space Telescope Science Institute (STScI) or
    European Space Observatory (ESO) servers.
    See http://archive.eso.org/dss/dss and/or
    http://archive.stsci.edu/dss/index.html for details.

Calling Sequence

      QueryDSS, targetname_or_coords, Im, Hdr, [IMSIZE= , /ESO, Outfile= ]


      TARGETNAME_OR_COORDS - Either a scalar string giving a target name,
          (with J2000 coordinates determined by SIMBAD (default) or NED), or
          a 2-element numeric vector giving the J2000 right ascension in
          *degrees* and the target declination in degrees.

Optional Inputs

    ImSize - Numeric scalar giving size of the image to be retrieved in
                arcminutes. Default is 10 arcminute.
    /ESO - Use the ESO server for image retrieval. Default is to use
            the STScI server
    /NED - Query the Nasa Extragalactic Database (NED) for the
            target's coordinates. The default is to use Simbad for
            the target search.
    OUTPUT - scalar string specifying name of output FITS file.
            If set, then the output IDL variables are not used.
    /STSCI - obsolete keyword, now does nothing, since STSCI is the default
    SURVEY - Scalar string specifying which survey to retrieve.
          Possible values are
          '1' - First generation (red), this is the default
          '2b' - Second generation blue
          '2r' - Second generation red
          '2i' - Second generation near-infrared
      Note that 2nd generation images may not be available for all regions
      of the sky. Also note that the first two letters of the 'REGION'
      keyword in the FITS header gives the bandpass 'XP' - Red IIIaF,
      'XJ' - Blue IIIaJ, 'XF' - Near-IR IVN
      /VERBOSE - If set, then the query sent to the DSS server is displayed


      Im - The image returned by the server. If there is an error, this
            contains a single 0.
      Hdr - The FITS header of the image. Empty string in case of errors.
      If the OutFile keyword is set then no outputs are returned (only the
      file is written).

Side Effects

    If Im and Hdr exist in advance, they are overwritten.


      Relies on a working network connection.


      Construct a query-url, call WEBGET() and sort out the server's


      Retrieve an 10' image surrounding the ultracompact HII region
      G45.45+0.06. Obtain the 2nd generation blue image.
      IDL> QueryDSS, 'GAL045.45+00.06', image, header, survey = '2b'
      IDL> tvscl, image
      IDL> hprint, header
      IDL> writefits,'dss_image.fits', image, header
  Note that the coordinates could have been specified directly, rather than
  giving the target name.
      IDL> QueryDSS, [288.587, 11.1510], image, header,survey='2b'
  To write a file directly to disk, use the OutFile keyword
      IDL> QueryDSS, [288.587, 11.1510], survey='2b', out='gal045_2b.fits'

Procedures Called


Modification History

      Written by M. Feldt, Heidelberg, Oct 2001 <mfeldt@mpia.de>
      Option to supply target name instead of coords W. Landsman Aug. 2002
      Added OUTFILE, /NED keywords W. Landsman April 2003
      Don't abort on Simbad failure W. Landsman/J. Brauher June 2003
      Added /VERBOSE keyword W. Landsman Jan 2009
      Make /STScI server the default W. Landsman June 2010
      Fix OUTPUT option W. Landsman June 2010

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