Outpost 23 was a Federation outpost along the Romulan Neutral Zone. In 2367, it was the key outpost in Starfleet's defenses along the border. In 2366, after receiving intelligence from a Romulan defector about a possible Romulan base at Nelvana III, this outpost received a warning from Starfleet Command. (TNG: "The Defector" ) This outpost was only mentioned in dialogue. According to Star Trek: Star Charts (p. 66), Earth Outpost 23 was located in the Beta Quadrant.