Chu'ot
From Halopedia, the Halo wiki
Chu'ot is a large, Neptune-sized, gas giant orbiting the star, Y'Deio, in Covenant space. The Kig-Yar homeworld, Eayn, orbits this planet.
Chu'ot was the only known Covenant-occupied planet that humanity already knew about before first contact with the Covenant. Its name, according to human astrographic naming conventions, is HD 69830 d.[1]