XEphem

XEphem
Screenshot of the XEphem 3.7.2 with the Earth and sky views
Developer(s)	Elwood C. Downey
Initial release	1990; 34 years ago (1990) ^[1]

Stable release	4.0.2^[2] / February 28, 2021; 3 years ago (2021-02-28)

Repository	github.com/XEphem/XEphem
Written in	C and Motif
Operating system	Unix-like
Type	Planetarium software
License	MIT License
Website	github.com/XEphem/XEphem

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

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History

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.^{[citation needed]} Its commercial edition was discontinued in 2016; the free version continued to be offered as proprietary software.^[3] In 2021, however, Downey relicensed XEphem's source code under the MIT License, raising the release version from 3.7.7 to 4.0.0 to highlight the change.^[4]

Algorithms and models

XEphem uses

The VSOP87D planetary theory (full and reduced precision) for Solar System ephemeris,
Approximation to DE200^[5] for the outer planets and Pluto, and
Formulae from J. Meeus (1982)^[6] 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.^[7] 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.^[8] This is also possible for the non-stellar catalogs in the ASCII .edb format, such as for HYPERLEDA.^[9]

XEphem can also read several astrometric catalogs in their original formats:

GSC 1.2^[10] and GSC-ACT^[11]
USNO A/SA 1.0/2.0^[12]
UCAC2 ^[13]

Numerical routines are used in PyEphem with permission of Elwood Downey.^[14]

References

^ "XEphem history". Retrieved 2015-09-28.
^ Downey, Elwood (2021-02-28). "Xephem installation on Ubuntu 20.02". Groups.io. Archived from the original on 2021-05-29. Retrieved 2021-05-29.
^ Downey, Elwood (2016-10-31). "thanks for using XEphem". Groups.io. Archived from the original on 2021-05-29. Retrieved 2021-05-29.
^ Downey, Elwood (2021-02-07). "XEphem now released under MIT Open Source license". Groups.io. Archived from the original on 2021-05-29. Retrieved 2021-05-29.
^ Chapront, J. (1995). "Representation of planetary ephemerides by frequency analysis. Application to the five outer planets". Astronomy and Astrophysics Supplement Series. 109: 181. Bibcode:1995A&AS..109..181C.
^ J. Meeus, Astronomical Formulae for Calculators (Willmann-Bell, Richmond, VA, 1982).
^ Digital Lunar Orbiter Photographic Atlas of the Moon
^ see e.g. Programs to generate XEphem 3.4 xe2 catalogs
^ CDS VizieR HYPERLEDA
^ CDS VizieR Guide Star Catalog
^ CDS VizieR GSC-ACT
^ USNO PMM catalogs
^ CDS VizieR UCAC2
^ "PyEphem Home Page".

External links

Official website
XEphem on GitHub
"openSUSE RPM". | "Linux RPMs".
VanDevender, Steve. "Programs to generate XEphem 3.4 xe2 catalogs".

This page was last edited on 10 April 2022, at 10:59

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