This directory contains the data, in binary format, of the GSC1.2
(Guide Star Catalogue, version 1.2, Brian McLean & Jane Morrison, STScI;
see also references in parent directory).

The GSC1.2 data are stored in a compact binary format similar to the GSC1.1;
a full description can be found in the presentation by A. Preite-Martinez
and F. Ochsenbein in "Handling & Archiving Data from Ground-based Telescopes",
Trieste 1993, ESO Conference and Workshop Proceedings No 50 p. 199
(ISBN 3-923524-53-6); the file "format.html" described the file structures.
The actual GSC data are stored in the directories N* (Northern hemisphere) 
and S* (Southern hemisphere).

The directory src contains the source programs which work on these
binary files. There are two programs which can be used, normally stored
in the bin subdirectory (here compiled for a Sun Solaris 2.x):

1. decode.exe transforms one binary file (e.g. N8230/4619.GSC ) into 
   the original GSC format comprising the 10 columns 
   GSC RAdeg DEdeg PosErr Pmag e_Pmag n_Pmag Class Plate Mult
   (see the descriptions in the ReadMe file of the parent directory)
   A sample output s provided below.
   [Added in August 2002] A -fits option can be used to recreate files
   in FITS format similar to the original GSC1.1 catalog

2. gsc.exe is a query program that retrieves GSC records around a position
   specified in J2000 equinox; several options allow various output 
   presentations, possibilities of selecting from magnitudes, or to query
   directly from a GSC region or number.
   The options are listed by the -h option.
   Details on the column meanings are listed by the -HELP option.

   The gsc.exe program uses the environment variable GSCDAT which
   specifies the root directory of the data (this directory).

   The gsc.exe program requires also the definition of the regions as the
   files bin/regions.bin and bin/regions.ind ; these two files
   can be recreated from regions.dat if necessary (normally not required,
   the byte swapping is executed by the program if necessary)

A version of these two programs compiled for PCs are also accessible in
the "bin-dos" subdirectory. To run these programs on a PC, you need to:
1. Create a directory, e.g. C:\GSC
2. Copy recursively the files and directories
3. Copy the files "decode.exe" and "gsc.exe" of the bin-dos subdirectory
   to a location known by your PATH
4. Define the variable GSCDAT pointing to the root of the data, e.g.
   SET GSCDAT=C:\GSC (should be added to the AUTOEXEC.BAT file)

NOTE: a client-server program "findgsc" included in the package
ftp://cdsarc.u-strasbg.fr/pub/cats/cdsclient.tar.gz
can query the any of the 3 versions of the GSC from any remote site
connected to Internet (it interacts directly with the gsc.exe program
running in daemon mode at CDS). It you use this cdsclient package, 
there is no need of copying all this stuff...

====================================================================
First result lines of the application of the program decode.exe 
on N8230/4619.GSC:
====================================================================
0461902665 011.96947 +84.37546   0.3 14.75 0.40  1 0 027O F
0461900014 027.64523 +84.37558   0.2 14.09 0.40  1 0 00A5 T
0461900014 027.64494 +84.37561   0.2 14.27 0.37  1 0 027O T
0461900046 020.36377 +84.37709   0.2 14.01 0.37  1 0 00A5 T
0461900046 020.36370 +84.37709   0.2 14.00 0.40  1 0 027O T
====================================================================
Questions, problems, etc...              question@astro.u-strasbg.fr
Francois Ochsenbein                    03 November 2000, 02 May 2001