This is a fork of the Celestia universe simulation software. The final release of Celestia was v1.6.1, released on 2011-06-12.
There have been subsequent commits on the source repository, primarily to add newly discovered objects; to my knowledge, these have never been released.
Key links:
- The original project site: http://www.shatters.net/celestia/
- Source code imported from: https://sourceforge.net/p/celestia/code (Subversion)
The original repository contained a number of tags, which have been preserved. A few versioning branches have been tagged and pruned as well.