XEphem

XEphem is a Motif based ephemeris and planetarium program for Unix-like operating systems developed by Elwood C. Downey.

History
XEphem started as a Unix and Motif conversion of the IBM PC-based . It was initially released in December 1993 with version 2.5. The most recent stable version is 3.7.6 (2013). XEphem's source code is available, but its free usage is restricted for personal and educational purposes only. The full set of catalogs is only distributed with a purchase of the commercial version.

Algorithms and models
XEphem uses
 The VSOP87D planetary theory (full and reduced precision) for Solar System ephemeris,
 Approximation to DE200  for the outer planets and Pluto, and
 Formulae from J. Meeus (1982) for Jovian and Saturnian natural satellites
 Model by the Bureau des Longitudes for Martian and Uranian natural satellites
and includes
 About 452 million stars from both the Tycho-2 Catalogue and a magnitude limited subset of the Guide Star Catalog II,
 About 1 million deep sky objects mainly from a subset of HYPERLEDA,
 About 288,000 minor planets and comets orbital elements from the IAU Minor Planet Center and Lowell Observatory (that can be updated),
and other specialized catalogs. It also include the Digital Lunar Orbiter Photographic Atlas of the Moon. XEphem is a client for Internet data sources such as the Digitized Sky Survey, Solar and Heliospheric Observatory, AAVSO light curves, and global temperature and cloud coverage. Through the Instrument Neutral Distributed Interface, XEphem can control some models of amateur telescopes, such as by Meade, Celestron, and Vixen, and auxiliary telescope components.

Catalogs 
While the free version of XEphem only includes a subset of the SKYMAP Master Catalog and the Messier Catalog, the internal format of the remaining catalogs can be inferred from the source code, and e.g. the internal binary Tycho-2 catalog can be generated from the original data. This is also possible for the non-stellar catalogs in the ASCII .edb format, such as for HYPERLEDA.

XEphem can also read several astrometric catalogs in their original formats:
 GSC 1.2 and GSC-ACT 
 USNO A/SA 1.0/2.0
 UCAC2 

Numerical routines are used in PyEphem with permission of Elwood Downey.

See also 

Cartes du Ciel
Celestia
Digital Universe Atlas
Google Mars
Google Moon
Google Sky
Hallo Northern Sky (HN Sky)
KStars
NASA World Wind
RedShift
Starry Night
Stellarium
TheSky
Universe Sandbox
WinStars
WorldWide Telescope

References

External links 
 
 Programs to generate XEphem 3.4 xe2 catalogs

Category:Planetarium software for Linux
Category:Science software for MacOS
Category:Astronomy software