Summary
Presumably a UNSC vessel. In a promotional transmission for Halo: Combat Evolved featured on Bungie's website, the Hermes II received a message from the CAR-class Covenant Cruiser, the Contrition.
NOTE: Nothing else about this object is known. It is possible that the Hermes II is a station or even a planet. However it is referred to as a "SCS" class ship, the same letters which preceed the Pillar of Autumn. Therefore it is possible that this is a Halcyon-class cruiser, it is impossible to confirm this.