Xephem Software

10-24-01 Update: Version 3.5 of this software has been released, including a Windows version that sells for $180, a Linux/Unix version that comes prebuilt with manuals, databases, and support for $80, and of course the source code is still free for the Linux/Unix users. Click here for more information.

The AAVSO has worked closely with Elwood Downey of the Clear Sky Institute to incorporate information from the AAVSO International Database into his popular astronomical software package called Xephem. Those who use version 3.4 or later of his software will be able to plot light curves automatically from inside the program with just the click of a mouse.

Xephem is a very powerful and popular astronomical software package available for various UNIX platforms, including Linux. It is also completely free. Xephem is the de facto standard for astronomy packages on UNIX and it is fast becoming the standard by which all programs, commercial or not, are compared. The February, 2000 issue of Sky & Telescope included a glowing review of Xephem titled "Xceptional Software".

When using the program, you simply right click on an area of the sky and choose "Search For Variables". The five closest variables to the area are displayed. Simply select one and a light curve will be generated from the AAVSO database. You can then tweak the lightcurve by plotting for other time periods. The only requirement is that you need to be online while running the program.

Below is a screen shot of what a light curve looks like from within Xephem:

Curve Dialog Box

Xephem can be purchased on CDROM with a User Manual and 200MB of extra databases for $69.96 from http://www.clearskyinstitute.com. You can also download it for free from one of the locations below:

We would like to thank Elwood Downey and the Clear Sky Institute for his valuable work on behalf of the AAVSO for this product. Additionally, we would like to applaud him for creating such a wonderful software product available for free to the astronomical community.