xsky is an X Window System program which is essentially an interactive night sky atlas for astronomy. Stars are plotted with colors corresponding to spectral class, and size corresponding to apparent magnitude. Non-stellar objects are drawn in several shapes according to the type of object represented. Right ascension and declination lines can be generated, and constellation boundaries and outlines are available. A PostScript file containing all this information can be generated for printing. For a complete exposition of xsky's capabilities, please see the SUMMARY file in the distribution.
The familiar actions of scrollbars, sliders, and pointer gestures such as clicking and rubberbanding can be used to move around the sky, adjust the magnification, select a region to view, and bring up detailed catalog information on any object. Objects can be located by name or position, and labelled with either catalog labels or custom user labels.
xsky makes use of machine-readable astronomical object catalogs made available by the National Space Sciences Data Center, located at the Goddard Spaceflight Center in Greenbelt, Maryland, which is administrated by the National Aeronautics and Space Administration. Thanks are due to them for providing this much-needed data distribution service.
Supported catalogs are (abbreviations used by xsky in parentheses):
a) the Yale Catalog of Bright Stars (YBS)
b) the Revised New General Catalog of Non-Stellar Objects (RNGC)
c) the Revised Optical Catalog of Quasi-Stellar Objects (QSO)
Support is included for the following catalogs, but the catalogs
themselves are not included in this distribution:
d) the Smithsonian Astrophysical Observatory Star Catalog (SAO)
e) the General Catalog of Variable Stars (VAR)
f) the Washington Catalog of Double Stars (DBL)
Support is included for the following catalogs on the NASA
Astronomical Data Center CD-ROM:
g) the Bright Star Catalog, 5th revised edition (BSC5)
h) the Smithsonian Astrophysical Observatory Star Catalog (SAOJ2000)
i) the Washington Catalog of Double Stars (WDS)
j) the General Catalog of Variable Stars (GCVS)
k) the New General Catalog of Nebulae and Clusters - 2000.0
l) the Uppsala General Catalog of Galaxies
Please note that catalogs (a) - (f) are supported only in the abridged versions available as part of the xsky distribution. Catalogs (a) - (c) are distributed with xsky, and catalogs (d) - (f) are available separately via anonymous FTP.
Additionally, xsky supports a user catalog. The intention of the user catalog is to enable the addition of comets or asteroids to create customized finder charts for transient objects.
This program has been rather thoroughly tested under Ultrix, running both the DEC X11R4 server and the MIT X11R5 server, and has since been upgraded to run with MIT X11R6. It should build from the Imakefile properly, but a Makefile.std is included for those unable or unwilling to fool with imake.
xsky is known to run under a wide variety of other Unix and Unix-like operating systems, including SunOS, FreeBSD, NetBSD, Linux, HP-UX, SGI Irix, and IBM AIX. Thanks to its total reliance on Athena widgets, essentially no porting effort is required in the usual case.
Suggestions for improvements are actively solicited, but please be aware that this is a part-time, off-hours project for me, and implementation could take awhile. It would certainly go faster if you included the code along with your suggestions! Any such contributions, if incorporated, will be gratefully acknowledged.
Contact the author at xsky@mail.astrotrf.com. Please begin the subject line with "xsky".