There are a few things to watch out for in using the STSDAS gasp
package with the HST Guide Star Catalog CD-ROMs.  Some of these have
been fixed in later versions and patches to STSDAS, but older
installations may need to be especially careful.


o  Apply the hsfs patch to allow the CD-ROM to be mounted and accessed
   as part of the file system.  See the file README_CD in the STSDAS
   gasp package directory (gasp$README_CD) for instructions.

o  The cdrom task is obsolete and no longer available, even though it
   may appear in the package menu.  You can read or copy files directly
   from the CD-ROMs once the hsfs patch has been applied and the disks
   have been mounted.  The gasp tasks access the files directly.

o  You need to extract the "index table" from the CD and reformat it as
   an STSDAS binary table.  This table provides the location of every
   GSC region on the sky and permits the gasp tasks (particularly
   sgscind) to determine which files to read on the CDs.  Use the task
   stgindx to get the file from the disk.  This is a "hidden" task that
   does not appear in the package menu.  The help for stgindx in older
   versions of STSDAS is incorrect.  There are two task parameters:

   index -- specifies the location of the output index file in STSDAS
   binary table format.  This is normally "gasp$index" specifying the
   gasp "package directory" part of the STSDAS system.  You can put it
   anywhere, but you then also need to change the index parameter in
   the sgscind task to match.  You need not (and indeed should not)
   include the file name extension (".tab") on the index table name
   although the file name will have this extension when it's created.

   cdfile -- specifies the name of the FITS format table on either
   GSC CD-ROM disc.  The path depends on how the CD-ROM was installed
   in your particular system.  For example, at ST ScI, both discs are
   available, on "/data/gsc1" and "/data/gsc2".  The path to the index
   table is then "/data/gsc1/tables/regions.tbl" (the default value for
   the index parameter).  This does require the full path name and the
   extension ".tbl".

o  Make sure the parameters cdrom_north and cdrom_south for the sgscind
   task specify the correct path to the root directory of the GSC disks
   as mounted in the file system.  And make sure the index parameter
   specifies the correct location for the index table (see the previous
   bullet).  As indicated above, these depend on the installation.  At
   ST ScI, the discs are available on "/data/gsc1" and "/data/gsc2".

o  Before running regions or targets, make sure you use
   "set imtype=hhh" in the cl to work around a problem in the FITS
   conversion task.  You can put this in the login.cl file.