Tau Ceti system
From Halopedia, the Halo wiki
Template:FOF-1 The Tau Ceti system is a planetary system 11.9 light-years from Earth. Like Sol, Tau Ceti is a yellow-orange dwarf. This system was conquered by the Covenant in the 2530's. The Covenant battle station Unyielding Hierophant was located in this system. The station was destroyed by UNSC forces September 13, 2552.
Tau Ceti is notably also the seting for Marathon.