The USS Enterprise was en route to Starbase 19 in 2267, when they diverted to respond to a distress call from planet Donico II. (TOS - Constellations short story: "See No Evil") Starbase 19 was one of two Starfleet facilities closest to the last reported position of the USS Sphinx, although there were no records of the ship docking there. (TOS - Section 31 novel: Cloak) In 2285, the Enterprise stopped at the station to pick up Ambassador Robert Fox, and replacement crew members. The Orion agent, Enigma infiltrated the Enterprise at the station. (TOS comic: "Who Is... Enigma?")