A Federation monitoring station destroyed by V'Ger as it approaches Earth in Star Trek: The Motion Picture.
Epsilon IX is a Federation station in deep space that tracks the course of a vast energy cloud in Star Trek: The Motion Picture. Its crew observes the cloud destroying three Klingon battlecruisers and reports to Starfleet.
When the cloud reaches the station, it destroys Epsilon IX too, as Kirk watches from the Enterprise. The cloud, V'Ger, is heading straight for Earth, and the station's loss reveals the threat.