Java Astro Library

Ten years ago I had a little interest in astrology. I studied some books and had the idea for an astro-chart real-time watch, some kind of watch that shows the wheel chart for the actual time just like a simple wristwatch. After releasing my Zodiac Watch applet in 2000 I got a lot of requests for its source. So I created AstroLib as branch from Zodiac Watch applet's source in 2003. I removed all painting and user interface routines to create a library.

This is AstroLib
... a free Java library for astro charting calculations. There are house system and planet position calculation methods together with date/time and location conversion routines. For a given time the positions of the planets in the zodiac are calculated. There is no code for graphical representations or drawing a chart. The library contains just methods for calculating the data needed to build a chart. Some methods were simply ported from Walter 'Cruiser1' Pullen's Astrolog 5.40 (which is written in C) and converted to Java. Part of the code is commented in German, but variables and methods are all named in English.

The library is used as shown in the Demo class' main method:

   // get a horoscop instance
   TextHoroscop horoscop = new TextHoroscop();
   // set your desired planet position calculation algorithm
   horoscop.setPlanet(new PlanetAA0());
   // set your desired house system calculation algorithm
   // may be anything from the at.kugel.zodiac.house package.
   horoscop.setHouse(new HousePlacidus());
   // set your user data time value
   horoscop.setTime(1, 12, 1953, 20);
   // set your user data location value
   horoscop.setLocationDegree(-16 - 17.0/60, 48 + 4.0/60);
   // calculate the values
   horoscop.calcValues();
   // do something with the data, e.g. output raw data
   System.out.println(horoscop.toString());

In case you want to add or change something, there are the following packages:

• The main package contains the TextHoroscop class, which uses the house system and planet calculation classes to calculate the astro-chart data.
• util contains some independent calculation utility functions and classes.
• planet contains the different planet position calculation algorithms. This package is only dependent on the util package. All planet position algorithms are subclasses of PlanetBasic which itself implements PlanetInt. New and more accurate planet position algorithms must implement PlanetInt and may wish to extend PlanetBasic to inherit common functionality, but are not forced to do so. There is only PlanetAA0 available at the moment, which is not very accurate.
• house contains the different house systems. All house system calculation algorithms are subclasses of HouseBasic which itself implements HouseInt.

Download and Installation
Download AstroLib 1.13 (70 KB), together with source. Extract the astrolib-*.zip and add astrolib.jar to your classpath. AstroLib is JDK 1.1 compliant and does not depend on any other libraries. AstroLib is Open Source under the GPL license.

The library is not actively developed any more, in fact it never was. The last changes I made were adding the Demo class in 2004 and fixing a bug using time zones in 2005 (thanks to Rastislav Szabo for reporting it). Today I reformatted the code and fixed some warnings. That's it folks.

FAQ
Q: Are there any chart drawing functions as in Zodiac Watch? A: Unfortunately the drawing routines are tightly coupled to the applet code and the browser user interface. I was able to extract the calculation routines and put them into a separate package, but this is not possible for the drawing code itself.

Q: The co-ordinates of the planets are within 1 minute difference from other available chart generation programs. But for the co-ordinates of the moon there is a 10 to 20 degree difference and the positions of the houses are absurd. What is wrong? A: Using a wrong time-zone results in a wrong local time. This affects the moon and the houses, but not the slower moving objects. Also make sure to enter negative longitude in the east zone and negative latitude below equator.

Q: Is there any code for computing the nodes of the moon? A: No, AstroLib can't do that.

Q: What kind of zodiac is calculated: Actual constellation divisions or the classic 30 degree each division? A: Traditional 30 degree per sign.

Update 24 April 2009

Jastrolog - Astrolog Port

Christian just convinced me to start a new project on SourceForge: Jastrolog, an Astrolog Port. Astrolog is a free astrology software program since 1991. Astrolog can create horoscopes, natal charts, and calculate current planetary positions in sidereal, traditional, and heliocentric formats. We believe it to be a bit of a cultural legacy. It deserves to live into the 21st century. As long as it is in C/C++ it has no chance. We might use AstroLib as a starting in porting the whole Astrolog and/or Astrolog32 to Java.