Ephemeris computation software, written between 2000 and 2002, not modified since.
Writen in java 2, still works in 2018 on a java 8 JVM.
Unmaintained project

Contains :
- Implementation of high-precision ephemeris for planets, using analytical
theories of the BDL (Bureau des longitudes) : VSOP87 (Mercury to Neptune) , ELP82 (Moon), Pluto99.
- Sky chart drawing

Originally published on http://www.astrosurf.com/jephem
Published in a git repository because some code can be re-used.

Written to explore ephemeris computation and to have a GPL alternative to Swiss Ephemeris.
Became useless when Swiss Ephemeris was released in GPL.

Javadoc : http://www.astrosurf.com/jephem/informatic/javadoc/JEphem/index.html

This program is mainly interesting for its implementation
of high precision ephemeris computation and exhaustive tests.
It uses VSOP87 (version A), based on the work of the BDL, using XEphem's code as a guide.
Also contains an implementation of planet velocities.
See these pages at astrosurf.com :
- VSOP87 presentation, precision :
  http://astrosurf.com/jephem/astro/ephemeris/et300VSOP_en.htm
- VSOP87 build process (why I choosed VSOP87 A ; formulae for planet velocities) :
  http://astrosurf.com/jephem/astro/ephemeris/et320buildVSOP_en.htm
- VSOP87 truncation :
  http://astrosurf.com/jephem/astro/ephemeris/et350truncateVSOP_en.htm
  (if you are interested by a truncated version of VSOP87, also look at Meeus' Astronomical Algorithms).
- VSOP87 tests :
  http://astrosurf.com/jephem/astro/ephemeris/et380testVSOP_en.htm

Also contains java implementation of various astronomical high precision computations :
precession, nutation, delta T (TAI - UTC).

Rudimentary sky chart drawing contains code that can be re-used :
- A page describing coordinate transformations to go from equatorial coordinates to screen coordinates :
  http://astrosurf.com/jephem/astro/ephemeris/et520transfo_en.htm
- List of constellations and coordinates of their boundaries :
  http://astrosurf.com/jephem/astro/skymap/sm150constellationData_en.htm