Watch This Space

by Eric Foster-Johnson

March 28, 2002 —

If you are interested in the night sky, then you'll want to take a look
at a cool astronomy application called XEphem. XEphem is billed as an
interactive cross-platform astronomical software ephemeris, which is a
listing of the heavenly bodies' predicted positions.

All this package's features are pleasantly surprising. XEphem can plot
the positions of planets, stars, and satellites, as well as display
star plots, 3D simulations of planets, and even overlay imagery such as
pictures of Mars, on your plots. All in all, XEphem is rather fun for
an amateur like me, but a number of features are also available for
professionals. I especially like the aptly named "Mission Control"
graphical format for plotting satellites' positions.

The raw data that powers XEphem's calculations derive from publicly
available astronomical databases. XEphem downloads data over the
Internet from a number of formats including Digitized Sky Survey FITS
files and AAVSO light curves. It can display real-time Earth weather
information from University of Wisconsin at Madison data on cloud
cover, land, and sea temperatures.

With the handy spreadsheet mode, you can convert between different
coordinate formats such as ecliptic, equatorial, galactic, and
horizontal coordinates.

Created by Elwood Downey, XEphem runs on Windows, MacOS X, Linux,
FreeBSD, and other UNIX and UNIX-like systems. XEphem can be downloaded
from http://www.xephem.com, or you can purchase a CD-ROM and manual set
for the various supported platforms.

UPDATE: Linux Accounting

I covered SQL-Ledger (http://www.sql-ledger.org), a Web-based
accounting package in a previous dispatch
(http://www.itworld.com/nl/lnx_desktop/03072002). In addition to SQL-
Ledger, you may want to also look at Nola, at http://nola.noguska.com.
Nola has received some good comments from users and on the Web.

ITworld