XEphem 3.5.2

“Hey! What’s this XEphem (eks-i-'fem) that I keep hearing you astro-geeks going-on about?”

According to its developer, Elwood Downey, it’s “The Serious Astronomical Software Ephemeris.” And I know that sounds pretty, well, serious. What can we glean from the Xephem website at http://www.clearskyinstitute.com/xephem/xephem.html? That the rather odd name for this program is a combination of X-Windows (as in Unix) and ephemeris (as in astronomical ephemeris, natch). Confused yet? It’s “The only scientific-grade interactive astronomical ephemeris software package that is available on all leading platforms: Microsoft Windows, Apple Macintosh and UNIX-like systems including Linux and FreeBSD!”

“Come on now! WHAT IS XEPHEM?!”

OK, OK, keep your shirt on. It’s simple, XEphem is a small revolution in astronomy software. It’s an ephemeris generator, sure, but it’s also a superb planetarium program. And it has advanced features and an incredibly “open” structure that let you add catalogs and images to make it into one of the strongest “deep sky” programs I’ve ever seen, more than powerful enough to take on the most advanced observing programs and to leave some very advanced (and pricey) astronomy software in the dust. A very truncated list of XEphem’s list of features includes:

• Computes heliocentric, geocentric and topocentric information for all objects;
• Has built-in support for all planets; the moons of Mars, Jupiter, Saturn, Uranus and Earth; central meridian longitude of Mars and Jupiter; Saturn's rings; and Jupiter's Great Red Spot.
• Allows user-defined objects including stars, deepsky objects, asteroids, comets and Earth satellites.
• Offers many large databases including Tycho, Hipparcos, GSC, USNO.
• Graphically displays a 24 hour period showing when any selected objects are up;
• Displays 3-D stereo views of the Solar System that are particularly well suited for visualizing comet trajectories;
• Sorts and prints all catalogs with very flexible criteria for creating custom observing lists;
• Downloads current asteroid and comets lists from Lowell and MPC;
• Downloads timely Earth satellite orbital TLE parameters;
• Downloads Digitized Sky Survey FITS files from STScI or ESO;
• Displays seti@home client progress and plots position being processed on Sky View map; ;
Oh…and it’s FREE.

“FREE? Yeah, right. What’s the catch? There’s always a catch.”

Well, there is one small catch…to run XEphem in an optimum fashion on a PC, you really need to run it under the Linux operating system. The Windows “version” is not free (or even close to it), as it’s really the Unix/Linux version with included software tools (which are what you’re paying for) to make the thing run under Windows.

“Linux?! ARRGH! The ultimate geek pastime! Lemme out of here!”

Now, hold on just a minute, Bunky! Yes, in the past Linux has been, along with its brother/cousin Unix, the max in geekware: hard to install, hard to learn, hard to fix when things go wrong. Luckily, though, things have changed. Modern distributions (“distros”) of Linux, and particularly the Red Hat distro are just as easy to install as Microsoft Windows (well, almost). With a little help from a computer savvy buddy, you can even partition off a couple of gigs of hard drive space on your Win Box, install Linux in that partition, and happily run XEphem and a wealth of other Linux/Unix astro software (there’s a lot out there; especially image processing stuff) while not giving up your beloved Windows. And you might even learn something about computers in the process!

While Linux is free, I advise buying a book/CD package of your favored distribution (some popular distro “brand-names” other than Red Hat are Debian and Mandrake). These sets are available in the computing sections of local bookstores and ensure that you have help during the install via the book (most how-to-use-Linux books are far more understandable than the readme files on the CDs!). You’ll also have a good reference source once you’ve got the Penguin (Tux the penguin is the Linux mascot) up and going!

As for XEphem itself, it’s available either as a relatively inexpensive CD or as a free download off the website. The CD is nice, since it has many astro-catalogs included, but is not required. The catalogs can be downloaded from many sources on the net once you’ve got the basic configuration of the program up and running. Actually, I don’t recommend the free download from the website either—nor if you’re a Linux/Unix newbie. It’s a source (code) file that must be compiled, a task you may find difficult and scary at first. Instead, look around the web—there are quite a few sources for the XEphem RPM (a ready to install version of the program—you basically click in your X-Windows desktop and go). Just use Google to search for XEphem RPM.

“I’ve got Linux up and going, and XEphem is working. But I’m not sure I like it. It’s weird.”

I wouldn’t call XEphem weird, really, but it is different. Practically every astronomy-planetarium program we’ve seen come down the pike since the DOS days and Skyglobe 3.6 shows a pretty, pretty star field when the program opens. Not XEphem. Instead, you’re greeted by the “main menu” display. This is the central control center for the program, and is the place where you’ll do things like set date, time, location, load data files and access the program’s graphical displays. Once you’ve got these parameters set to your liking, you can save them from here, too. You can do some practical work here as well, including generating ephemeris tables (this program is called xEPHEM, after all).

(page 1 of 2. Click "Next" bellow to read page 2...)

Added:  Friday, August 01, 2003
Reviewer:  Rod Mollise
Score:
Related Link:  Clear Sky Institute
Hits: 2715
Language: eng
Page: 1/2