XEphem(1X)

Name
XEphem - an interactive astronomical ephemeris for X

Syntax
xephem [-prfb] [-install {yes|no|guess}]

Description

XEphem is an interactive astronomical ephemeris program for X Windows systems with Motif. It provides many graphical views as well as quantitative heliocentric, geocentric and topocentric information for Earth satellites, solar system and celestial objects. XEphem contains extensive context-sensitive on-line help. Virtually none of that help is duplicated here so go ahead and run XEphem to learn more. The Main window of XEphem provides control and display of three basic services: observing circumstances, looping, and access to additional tools and displays. Observing circumstances includes location, date, time and atmospheric conditions (used for the refraction model). Looping refers to the ability to set up XEphem so that it automatically increments time at a desired step size and rate. Additional displays provide all of the graphical and quantitative information available, and always refer to the circumstances defined in the main menu. Tools provide access to plotting, searching, AAVSO, Seti@Home and more.

Options
-prfb displays all the built-in default resources, then exits. -install controls whether XEphem will install a private colormap. Without this option XEphem will try to decide automatically whether it is necessary. To force using a private colormap, use -install yes; to prevent it use -install no. The default automatic behavior is equivalent to -install guess.

Menu Tour
File This menu controls basic operation, including exiting. When XEphem is first started it may beep. This means a message has been put in the messages dialog, which can be displayed from this menu. Other chores here include setting up network access; a simple progress meter; controlling time and location information remotely. View This menu offers several graphical displays if the Earth, Moon and several planets; a user configurable table displaying; and Sky and Solar System views. Tools This menu gives access to tools which can plot any XEphem data items; save any data items to text files for easy export to other programs; enter an arbitrary function to evaluate and solve using any XEphem data items; access AAVSO online; monitor your Seti@Home client; show the Night at a glance; and find close pairs of objects. Data This menu gives control over which objects XEphem will work with. Objects may be created on the fly, read from catalog files, deleted or searched. A special category of objects known as Field Stars may be configured, which are very large catalogs of objects whose access has been optimized. Up to three User objects may be assigned for especially easy access in several other places throughout XEphem. Also here is a tool which can update Earth satellite orbital elements from the web. Preferences This menu offers several configuration choices. These will effect the overall appearance or behavior of XEphem. These choices, as well as fonts and colors, can be changed at runtime and saved to disk to become the new defaults. Help This menu offers overall information about B .XEphem; context sensitive help; several worked examples; references; version number and the Copyright statement.

X Resources
XEphem initial conditions are defined using a resource file. By default the file is named XEphem located in a directory also called XEphem in your $HOME directory. You will want to tune some of these to your taste and circumstances; most may be left unchanged.

Time zones
XEphem will attempt to obtain time zone information from the host operating system. If this fails for some reason, time zone offset and name may also be set manually at any time from the Main menu.

Author

Elwood Downey, email ecdowney@ClearSkyInstitute.com.

References

The latest information about XEphem is maintained at http://www.clearskyinstitute.com/xephem

The online Help entry on Credits lists many of the references, individuals and organizations which have contributed to XEphem.