Lya III was the inhabited third planet in the Lya system. This system, in Sector 30/489, was located near the Giles Belt and the Nel Bato system. This planet was home to a Federation starbase administered by Starfleet. Subspace messages sent from this starbase to ships near the Romulan Neutral Zone had a delay time of two hours and twenty-three minutes.
In 2366, Vice Admiral Haden was assigned to this starbase. During the Nelvana Incident, he was the representative of Starfleet Command and sent messages to Captain Picard aboard the USS Enterprise-D. (TNG: "The Defector")
Later that year, after completing its mission at Angosia III, Lya III was the destination of the USS Enterprise. (TNG: "The Hunted")
See also
According to the Star Trek: Star Charts (pg. 47), the Lya system was located in the Alpha Quadrant.