Chu'ot
From Halopedia, the Halo wiki
Chu'ot was 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 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]