The Koronus Expanse is the name given by the authorities of the Imperium of Man to a dangerous unexplored region of the Halo Stars located beyond the Calixis Sector in the Segmentum Obscurus. The Expanse is accessed through the Koronus Passage, a treacherous but navigable route through the great Warp Storms that bar passage to the Halo Stars beyond the way station of Port Wander on the edge of the Expanse.