XEphem(1X) XEphem(1X)

Name
XEphem - an interactive astronomical ephemeris for X11

Syntax
xephem [-prfb] [-install {yes|no|guess}] [-resfile <resourcefile>]
[-[no]splash]

Description
XEphem is an interactive astronomical ephemeris program for the X
Window System. It provides many graphical views as well as
quantitative heliocentric, geocentric and topocentric information for
Earth satellites, solar system and celestial objects.

XEphem primarily uses two directories at runtime. One is referred to
as the Shared directory, the other as the Private directory. Shared
is read-only and holds supporting files that can be shared among all
users on a system. Private is writable and one is expected to exist
for each user. See the section below on X Resources for more
information about defining these directories.

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 first thing to do once XEphem is up is configure the
browser interface. All of XEphem help is written in html and stored
in a file named xephem.html. The first entry in the Help menu brings
up a table of browsers and defines a command for each that will
invoke the browser and pass it the URL and anchor of the text to
display. XEphem comes configured to support several different
browsers. If yours is listed, just click the button to its left and
your help system should be working. If your browser is not listed,
please check the FAQ for the latest news.

Note that if you are running XEphem under cygwin on Windows, before
starting XEphem set an environment variable XEHELPURL to the full
path of the xephem.html file on your system using Windows path syntax
(not cygwin paths). This file is in the help directory within the
source directory of the master distribution. After this is in the
place, run xephem and it can use MS IE to display help.

The XEphem Main window is the master panel for setting up observing
circumstances, time looping, and for accessing all the additional
tools and displays. Observing circumstances includes location, date,
time, local magnetic deviation and atmospheric conditions (used for
the refraction model). Looping provides 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, which are always computed with
respect to the circumstances defined in the Main menu. Tools provide
access to plotting, searching, AAVSO and much more.


Command line Options
-prfb displays all the built-in default resources, then exits. Some
of them are described here.

-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.

-resfile <resourcefile> tells XEphem to use an alternate file for
initial resource settings. See below for the default situation.

-splash or -nosplash controls whether XEphem will display a progress
window front and center while it is coming up. The choice is yours
because this can be a useful sign of life on a slow system, or be the
source of an annoying flash on a fast system. The setting is
persistent so it will remain until changed.


Menu Tour
File

This menu controls access to the System log; setting up network
access; accessing the gallery; displaying a progress meter;
controlling time and location information remotely; and keyboard
accelerators for time stepping.

View

This menu offers several graphical displays if the Sun, Earth, Moon
and several planets; a user configurable data table; 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; show the Night at a glance; find
close pairs of objects; convert among various astonomical coordinate
systems; and a handy log for taking observing notes.

Data

This menu gives control over which objects XEphem will work with.
Objects may be created on the fly, read from catalog files,
downloaded from the Internet, 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. Any number
of Favorite objects may be defined for especially easy access in
several other places throughout XEphem.

Preferences

This menu offers several configuration choices and tools for changing
fonts and colors used throughout XEphem. These choices can be
changed at runtime and saved to disk to become the new defaults.

Help

This menu offers overall information about XEphem; context sensitive
help; references; version number and the Copyright statement.


X Resources
When first started, XEphem looks for a file named .xephemrc in your
$HOME directory. It should contain one line of the form:

XEphem.PrivateDir: ~/.xephem

This defines the Private directory, where XEphem will store your
personal settings. The example line shown here, which is also the
assumption if the file is not present, means XEphem will create and
use a directory named .xephem for this purpose in your home
directory.

Within this directory a text file named XEphem will contain all the
Preferences that differ from those built in. One important entry
defines the Shared directory. This is in intended for multi-user
installations. XEphem looks here for support files. Unless defined
otherwise, the Shared directory is ".", that is, the current
directory.


Author
Elwood C. Downey, email ecdowney@ClearSkyInstitute.com.


References
The Web homepage, including the FAQ, 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.

XEphem(1X)