Deep-Space Anomaly 0198
From Halopedia, the Halo wiki
Deep-Space Anomaly #0198 is a UNSC catalogued unknown phenomenon. It seems to be some kind of derelict technology, though it's purpose is unknown. It is believed to be some kind of Forerunner remnant, as it appears to be a station containing Forerunner technology.
This anomaly is the site of the Multiplayer level in Halo: Combat Evolved called Derelict.
