Technical information about the Zodiac Watch

Years ago, when I was introduced to astrology, I was fascinated at once. I studied books about the signs of the zodiac and the information provided by wheel charts. Later I thought that it would be great to have some kind of watch that shows the wheel chart for the actual time just like a simple wristwatch. I started to search for calculation algorithms. At last I found some useful resources to code this astro-chart real-time watch. Note that I am a coder not an astrologer, so please do not ask me details about astrology.

Details about the code

Zodiac Watch is coded as JDK 1.1 compliant Java Applet using AWT components. Java 1.1 was used because it is supported by most browsers. The code was compiled with the J2SE 1.3 compiler using the options g:none, O, target 1.1 resulting in the smallest possible class code. Then the code was obfuscated with JODE (Optimize Decompile Environment) and packaged. The most recent version is 1.10, which needed about 180 hours to finish, including 35 classes with total 6840 lines of code.


If you are interested in Zodiac Watch and would like to use it on your own (astro-) site, please contact me.

If you are just looking for the Java source, have a look at AstroLib my astro charting calculation library.


Zodiac Watch is based on Michael Erlewine's "Manual of Computer Programming for Astrologers" from Matrix Software. Unfortunately the book was written for Commodore Basic (no local variables, no real subroutines, no modularity, ...) Some source code was taken from Walter 'Cruiser1' Pullen's "Astrolog 5.40", which is written in C. Astrolog seems to be based on the "Manual of Computer Programming for Astrologers", too, which made things a little bit easier.

Version History

System Requirements

As Zodiac Watch is a Java applet, your browser must support Java. Make sure that Java is enabled. (Do not confuse this with "Java Script" or "Scripting".) Most browsers support Java but for some, for example Netscape 6 or Opera, you will need a separate Java plugin. Plugins for Solaris, Linux and Microsoft Windows are provided by Sun, as well as links to plugins for other operation systems. If your browser has built in Java support, it must implement Java version 1.1 or higher, see Browsers' VM Version.