A default version of skymap.par should be set up on the system before skymap is used. The first time skymap is used in a directory, skymap.par will be read from a directory specified by the environment variable DEFAULT_DIR or the argument "-def" (or /home/mink/Defaults on any OIR system). When the program is run, parameters set on the command line override those values in the local copy of this file, which is updated to the new values. Thus only those parameters which are changed need to be entered on the command line.

The newdef program may be used to change the default directory name in the skymap executable file.

If skymap is run with no command line arguments or with a ? or "help", a brief description with a list of command line arguments and current parameter values is printed and the program exits.

A copy of the CD-ROM file tables/regions.tbl on a hard disk will speed the search for the proper Guide Star Catalog region to search. REGTAB should be set to the pathname to that file or to the one on the CD-ROM.

CDNORTH and CDSOUTH should be set to the pathnames of the root directories of the two volumes of the GSC CD-ROMs. If there is only one drive, set both to that drive's pathname and swap CD-ROMs as needed; skymap will fail gracefully if it cannot find the regions it is looking for on the current disk.