- The Ship Recognition Manual, Volume 4: Starships of the Original Series Era gives a registry of NCC-124.
In 2168, the Horizon discovered the inhabited planet Sigma Iotia II. The crew left behind a book, Chicago Mobs of the 1920s, which would influence the planet over the next century. Not long after the ship depart from Sigma Iota II it was destroyed under unknown circumstances. A distress call from the ship would be picked up by the USS Enterprise a century later. (TOS: "A Piece of the Action"; Ship Recognition Manual, Volume 4: Starships of the Original Series Era)