Athan Prime was the prime planet in its star system, orbited by at least one moon. It was the location of the Federation Fleet Museum in the early 25th century.
In 2401, the USS Titan-A traveled to Athan Prime to seek Commodore Geordi La Forge's assistance in extracting their away team from Daystrom Station. (PIC: "The Bounty")
Two days later, after the Borg seized control of the Federation fleet during Frontier Day celebrations, Admiral Jean-Luc Picard and his comrades returned to Athan Prime in a shuttle to retrieve the rebuilt USS Enterprise-D from the Museum. (PIC: "Vox")