XEphem is a
Motif based
ephemeris and
planetarium program for
Unix-like
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...
operating systems developed by
Elwood C. Downey.
History
XEphem started as a
Unix
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, an ...
and Motif conversion of the
IBM PC-based '. It was initially released in December 1993 with version 2.5. Its commercial edition was discontinued in 2016; the free version continued to be offered as proprietary software. In 2021, however, Downey relicensed XEphem's source code under the
MIT License
The MIT License is a permissive free software license originating at the Massachusetts Institute of Technology (MIT) in the late 1980s. As a permissive license, it puts only very limited restriction on reuse and has, therefore, high license comp ...
, raising the release version from 3.7.7 to 4.0.0 to highlight the change.
Algorithms and models
XEphem uses
* The
VSOP87D planetary theory (full and reduced precision) for
Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
ephemeris,
* Approximation to
DE200 for the
outer planets
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
and
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest ...
, and
* Formulae from J. Meeus (1982) for
Jovian and
Saturnian
natural satellite
A natural satellite is, in the most common usage, an astronomical body that orbits a planet, dwarf planet, or small Solar System body (or sometimes another natural satellite). Natural satellites are often colloquially referred to as ''moons'' ...
s
* Model by the
Bureau des Longitudes for
Martian
Mars, the fourth planet from the Sun, has appeared as a setting in works of fiction since at least the mid-1600s. It became the most popular celestial object in fiction in the late 1800s as the Moon was evidently lifeless. At the time, the pr ...
and
Uranian natural satellites
and includes
* About 452 million stars from both the
Tycho-2 Catalogue
The Tycho-2 Catalogue is an astronomical catalogue of more than 2.5 million of the brightest stars.
Catalogue
The astrometric reference catalogue contain positions, proper motions, and two-color photometric data for 2,539,913 of the brigh ...
and a
magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
limited subset of the
Guide Star Catalog II
The Guide Star Catalog (GSC), also known as the ''Hubble Space Telescope, Guide Catalog'' (''HSTGC''), is a star catalog compiled to support the Hubble Space Telescope with targeting off-axis stars. GSC-I contained approximately 20,000,000 stars w ...
,
* About 1 million
deep sky objects mainly from a subset of HYPERLEDA,
* About 288,000
minor planet
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''mino ...
s and
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
s
orbital element
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same ...
s from the
IAU
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
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
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
data sources such as the
Digitized Sky Survey,
Solar and Heliospheric Observatory
The Solar and Heliospheric Observatory (SOHO) is a European Space Agency (ESA) spacecraft built by a European industrial consortium led by Matra Marconi Space (now Airbus Defence and Space) that was launched on a Lockheed Martin Atlas IIAS lau ...
,
AAVSO
The American Association of Variable Star Observers (AAVSO) is an international nonprofit organization, founded in 1911, focused on coordinating, analyzing, publishing, and archiving variable star observations made largely by amateur astronomers ...
light curve
In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...
s, and global temperature and cloud coverage. Through the
Instrument Neutral Distributed Interface
Instrument Neutral Distributed Interface (INDI) is a distributed control system (DCS) protocol to enable control, data acquisition and exchange among hardware devices and software front ends, emphasizing astronomical instrumentation.
Introducti ...
, XEphem can control some models of amateur telescopes, such as by
Meade,
Celestron
Celestron is an American company based in Torrance, California, United States, that manufactures telescopes and distributes telescopes, binoculars, spotting scopes, microscopes, and accessories manufactured by its parent company, the Synta Technol ...
, and
Vixen
Foxes are small to medium-sized, omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull, upright, triangular ears, a pointed, slightly upturned snout, and a long bushy tail (or ''brush'').
Twelve sp ...
, 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 Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters'').
Because Messier was only int ...
, the internal format of the remaining catalogs can be inferred from the source code, and e.g. the internal
binary
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that ta ...
Tycho-2 catalog can be generated from the original data. This is also possible for the non-stellar catalogs in the
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because ...
.edb
format, such as for HYPERLEDA.
XEphem can also read several
astrometric
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way.
His ...
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
*
C2A
*
Cartes du Ciel
''Cartes du Ciel'' ("CDC" and "SkyChart") is a free and open source planetarium program for Linux, macOS, and Windows. With the change to version 3, Linux has been added as a target platform, licensing has changed from freeware to GPLv2 and the ...
*
Celestia
*
Digital Universe Atlas
Digital Universe Atlas is a free open source software planetarium software, planetarium application, available under the terms of the Illinois Open Source License, and running on Linux, Microsoft Windows, Windows, macOS (10.5 and above), AmigaOS ...
*
Google Mars
Google Earth is a computer program that renders a 3D computer graphics, 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposition, superimposing satellite images, aerial photography, and geog ...
*
Google Moon
Google Earth is a computer program that renders a 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposing satellite images, aerial photography, and GIS data onto a 3D globe, allowing users ...
*
Google Sky
Google Earth is a computer program that renders a 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposing satellite images, aerial photography, and GIS data onto a 3D globe, allowing users ...
*
Hallo Northern Sky (HN Sky)
*
KStars
KStars is a freely licensed planetarium program using the KDE Platform. It is available for Linux, BSD, macOS, and Microsoft Windows. A light version of KStars is available for Android devices. It provides an accurate graphical representation ...
*
NASA World Wind
*
RedShift
*
Starry Night
''The Starry Night'' ( nl, De sterrennacht) is an oil-on-canvas painting by the Dutch Post-Impressionist painter Vincent van Gogh. Painted in June 1889, it depicts the view from the east-facing window of his asylum room at Saint-Rémy-de-Provenc ...
*
Stellarium
*
TheSky
*
Universe Sandbox
*
WinStars
*
WorldWide Telescope
WorldWide Telescope (WWT) is an open-source set of applications, data and cloud services, originally created by Microsoft Research but now an open source project hosted on GitHub. The .NET Foundation holds the copyright and the project is manage ...
References
External links
*
*
* ,
*
{{DEFAULTSORT:Xephem
Free astronomy software
Planetarium software for Linux
Science software for macOS