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This compact version of the Guide Star Catalogue, ACT Version
(an all-sky astrometric and photometric catalog to support the operation
of the Hubble Space Telescope, The Association of Universities for Research in
Astronomy, Inc. ([c] 1989, 1992)) was prepared from the material kindly
supplied by Bill J. Gray from the Pluto Project
http://www.projectpluto.com/gsc_act.htm .
Reference for the creation of the compact version (300Mbytes) is:
    A. Preite-Martinez and F. Ochsenbein, and presented as
    "A Pocket version of the Guide Star Catalogue" in
    "Handling & Archiving Data from Ground-based Telescopes", Trieste 1993,
     ESO Conference and Workshop Proceedings No 50 (ISBN 3-923524-53-6),
     p. 199
(details at http://archive.eso.org/skycat/gsc-engine/node2.html)
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NOTE that a client/server program named "findgsc" allows to query the 3
versions of the Guide Star Catalogue in batch mode, as well as some other
very large catalogues on any Unix/Linux platform without having to actually
load the data, see:   ftp://cdsarc.u-strasbg.fr/pub/cats/cdsclient.tar.Z
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This directory includes executables and binary indexes for fast queries for
Sun-Solaris workstations; the C code which generates the executables is tar'ed
in file ../src.tar.gz
Executables for Sun-Solaris are in the "bin" subdirectory, 
and in the "bin-dos" subdirectory for PCs.

regions.bin, regions.ind : binary indexes of regions used by gsc.exe.
  (indexes stored as small-endian integers, can be used without
  transformation on other architectures including big-endians)

gsc.exe: query program which allows to retrieve the GSC stars in a
  small circle around a target position (or at a distance between two
  limits), or from a GSC-id identification (a number combining the region
  and star) with the -g option. This program has a lot of other options
  summarized with the -help option.

  To have gsc.exe running properly, two environment variables are required:
  GSCDAT :    the name of the directory which contains the [NS]* subdirectories;
  GSCBIN :    the name of the directory which contains the binary indexes.
  The default setup of these variables are:
  GSCDAT=/GSC  on Unix       set GSCDAT=\GSC     on MS-DOS
  GSCBIN=$GSCDAT/bin         set GSCBIN=$GSCDAT\bin

  The usage of two variables allow to move only the binary files ($GSCBIN)
  to a magnetic drive, leaving the bulk data ($GSCDAT) to a dedicated (e.g.
  optical) drive.

decode.exe:
  allows to rebuild the original GSC files from the binary version.
  For instance, to recreate the 4615 region, execute
  decode.exe ../N8230/4615.GSC
  A -fits option [added in August 2002] allow to generate FITS files, e.g.
  decode.exe -fits ../N8230/4615.GSC > 4615.fits

Questions, comments, suggestions are welcome!
Francois Ochsenbein, 1999 December 11
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        _/_/_/_/_/_/ . . .             Centre de Donnees astronomiques de
      _/                               Strasbourg
     _/                                http://cdsweb.u-strasbg.fr/CDS.html
    _/        _/_/  _/_/_/
   _/      _/      _/    _/            Francois Ochsenbein
    _/_/_/_/      _/    _/_/_/_/       Internet: francois@astro.u-strasbg.fr
         _/      _/    _/      _/         Phone: +33 88 15 07 55
          _/_/  _/_/_/        _/            Fax: +33 88 15 07 40
                             _/            Post: Observatoire Astronomique
                            _/                   11, rue de l'Universite
        . . . _/_/_/_/_/_/_/                     67000 STRASBOURG, France
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