The Phoenix Cluster was a stellar cluster.
In 2368, the USS Enterprise-D became the first Federation starship to visit the Phoenix Cluster, on a two-week surveying mission. Prior to the mission, several scientists transferred aboard the Enterprise from the USS Zhukov to assist. The mission was interrupted by the proliferation of a Ktarian game on board, part of a Ktarian plot to take over Starfleet. (TNG: "The Game")