The Federation starbase to which Geordi La Forge sent the Enterprise-D's saucer section in 2364 before taking the stardrive back to fight the weapon at Minos.
Starbase 103 is a Starfleet installation mentioned in the Next Generation episode The Arsenal of Freedom.
With Picard and the senior officers trapped on Minos and an automated weapon attacking the ship in orbit, acting captain Geordi La Forge decides to separate the Enterprise-D. He places Chief Engineer Logan in command of the saucer section, which carries most of the crew and their families, and orders it to Starbase 103.
La Forge then returns to Minos with the stardrive section and destroys the orbital drone. The starbase is not shown, but the order is one of the few occasions in the series when saucer separation is used to carry civilians to safety.