Cathius IX was a planet, somewhere in the space of the galaxy's Alpha or Beta Quadrants.
History and specifics[]
It was known for its exotic charms, and served as a shore leave destination for Starfleet officers in the early 24th century.
Ensign Abraham Silver was beaten to near-death in a Cathius IX casino after running up a large gambling debt. (SCE - Tales from the Captain's Table short story: "An Easy Fast")