A highly classified Federation station guarded by the USS Sargasso, which Nus Braka's pirates ransack in the Starfleet Academy episode Come, Let's Away.
Starbase J-19 Alpha is a 32nd-century Federation installation housing a secret research project. The Intrepid-class USS Sargasso is normally stationed there as its protection.
It is central to the Starfleet Academy episode Come, Let's Away. When cadets on a training exercise aboard the derelict USS Miyazaki are taken hostage by the predatory Furies, Admiral Vance accepts help from the pirate leader Nus Braka, and the Sargasso, which carries a sonic weapon effective against the creatures, is sent to the rescue.
That is what Braka wanted. With the guard ship drawn away, his Venari Ral attack the starbase, kill many of its personnel and plunder what it held. The USS Discovery is first to reach the scene. The episode ends with Starfleet counting the cost of having trusted him.