The Osiris orbited a lifeless moon, Ba'al had came here to prepare for confrentation with Darth Traya. His plan was to attract her here by destroying a cargo ship containing several artfacts from the old Telos academy. The Osiris waited as the cargoship to arrive before activated it's gravity wells generator to pervent the cargoship to enter hyperspace again.
Once that had happened, several wings of sith fighters left the Osiris and fired abon the cargoship, didn't take long to destroy it.
Make love, not toast.