In "Halo", what is the name of the planet which Installation 04 orbits?

The name of the planet on which Installation 04 orbits in the Halo universe is Threshold. Threshold is a gas giant located in the Soell system and serves as the primary celestial body of the Halo ring. It is an important location in the Halo lore as several events take place on or near this planet, making it a significant location within the game's narrative.