XEphem

Infobox Software
name = XEphem


caption = Screenshot of the XEphem 3.7.2 with the Earth and sky views
developer = Elwood C. Downey
latest release version = 3.7.3
latest release date = 24 March 2008
operating system = Unix-like
genre = Amateur astronomy/observational astronomy
license = Proprietary
website = [http://www.clearskyinstitute.com/xephem/]

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

XEphem uses
* The VSOP87D planetary theory (full and reduced precision) for Solar System ephemeris,
* Approximation to DE200 [ [http://adsabs.harvard.edu/abs/1995A%26AS..109..181C J. Chapront, Astron. Astrophys. Suppl. 109, 181 (1995).] ] for the outer planets and Pluto, and
* Formulae from J. Meeus (1982) [J. Meeus, Astronomical Formulae for Calculators (Willmann-Bell, Richmond, VA, 1982).] for Jovian and Saturnian natural satellites
* Model by the Bureau des Longitudes for Martian and Uranian natural satellitesand 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 [ [http://www.lpi.usra.edu/resources/lunar_orbiter/ 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.

XEphem started as a Unix and Motif conversion of the IBM PC-based "ephem". It was initially released in December 1993 with version 2.5. The most recent version is 3.7.3 (March 2008). 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.

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 [see e.g. [http://hexadecimal.uoregon.edu/xephemcatalogs/ Programs to generate XEphem 3.4 xe2 catalogs] ] . This is also possible for the non-stellar catalogs in the ASCII .edb format, such as for HYPERLEDA [ [http://cdsarc.u-strasbg.fr/viz-bin/Cat?VII/237 CDS VizieR HYPERLEDA] ] .

XEphem can also read several astrometric catalogs in their original formats:
* GSC 1.2 [ [http://cdsarc.u-strasbg.fr/viz-bin/Cat?I/254 CDS VizieR Guide Star Catalog] ] and GSC-ACT [ [http://cdsarc.u-strasbg.fr/viz-bin/Cat?I/255 CDS VizieR GSC-ACT] ]
* USNO A/SA 1.0/2.0 [ [ftp://ftp.nofs.navy.mil/pub/ USNO PMM catalogs] ]
* UCAC2 [ [http://cdsarc.u-strasbg.fr/viz-bin/Cat?I/289 CDS VizieR UCAC2] ]

References

See also

*Cartes du Ciel
*Celestia
*Stellarium
*KStars

External links

* [http://www.clearskyinstitute.com/xephem/ Official website]
* [http://hexadecimal.uoregon.edu/xephemcatalogs/ Programs to generate XEphem 3.4 xe2 catalogs]