Are you looking for ROOT-based simulator for ray tracing (ROBAST)?
This repository was cited in a few conference proceedings of the Cherenkov Telescope Array by careless mistakes by the authors (not me). You cannot get any ROBAST information here.
Please visit the ROBAST official website http://robast.github.io/ instead. You can find the master repository of ROBAST at https://github.com/ROBAST/ROBAST .
Please note that the old ROBAST website and its SVN repository at https://sourceforge.net/projects/robast/ are obsolete.