UNSC Weather Station Z/41

Weather Station z/41 is a United Nations Space Command facility in the Arctic on Earth. It is the setting for the Halo 3: Legendary Pack map, Blackout.

In the Weekly Update that unveiled Blackout, some of the Bungie guys joked that it was a "stupid and arbitrary name" with "no significance", and left it to the fans to find their own meaning in the name z/41.