AstroLib

A Java library of Astronomical Algorithms

This is a library of (hopefully) useful astronomical algorithms. This library is based on a class-oriented C++ library I wrote. The C++ library, in turn, was originally based on the C source code written by Bill Gray and available at the Project Pluto website.

It has been "transmogrified" a bit since it's origins. I've changed some things, reorganized some things, and added some things, using information from Jean Meeus' excellent book Astronomical Algorithms.

The biggest differences between this code and the Bill's original code are

1. It's in Java (duh ;-), so everything is a class or part of a class.
2. I added a lot of static constants to avoid "magic numbers" as much as possible - there's plenty enough of those in the orbital elements and formulas!
3. I used native types like int whereever possible, dropping Bill's original byte-frugal storage strategies. This eliminates Bill's "wrong-endian" byte alignment worries. In addition, Java only runs on 32-bit general-purpose platforms, so there's no need to fit things in a 64K segment :-).
4. I unwound some of Bill's clever algorithm implementations. I find as I get older (and hopefully wiser) that performance can always be tweaked if necessary, but code readability needs to be "baked in."

I use this code to run the astronomical servlets on the DVAA web site, in particular, the lunar phase display on the home page, and the " Darkness Planner" information page.

Questions are welcome.

Copyright Restrictions: In the spirit of Bill's original source, you are free to use this for non-commercial purposes - but please give us a mention if you do so! For commercial usage, please contact me first.

Mark Huss - March 2003
 

History

• Version 1.0 - original release
• Version 1.1 - rationalized the code a bit, added Exceptions, added a load of javadoc documentation/comments, and switched from Make to Ant for the build.
• Version 1.1.1 - fixed LunarCalc.Lunation() and bug in Lunar( time ) constructor
• Version 1.1.2 - fixed LunarCalc.summary() and RiseSet.getTimes() functions.
• Version 1.1.3 - fixed a couple of bugs in Lunar() and one in DateOps. (Thank you to Tom Fly for spotting these.)
  - Added optional Calendar parameter to TimeOps.tzOffset() functions, so non-local TZ calcs could be performed.
• Version 1.1.4 - added XYZ to LocationElements. - Added RightAscention and Declination to PlanetData (Thanks again to Tom Fly).
  - Made sure all dependent Util classes are included!