Awesome

lunar

Basic astronomical functions for solar system ephemerides, time systems, coordinate systems, etc. This includes some utilities based on these functions, such as a calendar computer and a utility to numerically integrate asteroid orbits. The code can be built for Windows, Linux, or BSD, and probably OS/X. Some documentation (in need of updates) is at

http://www.projectpluto.com/source.htm#astrocalc

On Linux, run make to build the library and various test executables. (You can also do this with MinGW under Windows.) In Linux, you can then run make install to put libraries in /usr/local/lib and some include files in /usr/local/include. (You will probably have to make that sudo make install.) For BSD, and probably OS/X, run gmake CLANG=Y (GNU make, with the clang compiler), then sudo gmake install.

On Windows, run nmake -f lunar.mak with MSVC++. Optionally, add BITS_32=Y for 32-bit code.