Unidentified moon (Sub-sector 35)
From Halopedia, the Halo wiki
This unidentified moon is a natural satellite of an unknown celestial body in an unknown star system in Sub-Sector 35. It was once inhabited by the Forerunners over 100,000 years ago, and is the location of Line Installation 1-4.
During the Human-Covenant War in 2552, an Office of Naval Intelligence vessel, Long Time Coming, and a Covenant assault carrier, Clarity of Faith, crash-landed here after being disabled by the Line's weapon systems while in Slipspace. Some of their personnel were taken by Gatherers to Line Installation 1-4's main facility for study by 686 Ebullient Prism, the Monitor of the installation. They eventually managed to escape with the help of their compatriots and destroy the Monitor.
List of appearances