From Halopedia, the Halo wiki
A star map is a map displaying various locations in and beyond a galaxy.
On November 3, 2552, following the aborted firing of Installation 05, the display in the Control Room showed a star map depicting the various locations of the Halo Array as 343 Guilty Spark explained that the Array was now in standby mode to be activated at the Ark.
In August 2558, the crew of the Ace of Spades visited Installation 07 where Spark used the Librarian's coordinate key on the Halo ring's Cartographer. After Rion Forge added her touch as a Reclaimer, the Cartographer displayed a star map leading to a specific location on New Carthage where the third piece of the key was located.
List of appearances