Sublime Transcendence
From Halopedia, the Halo wiki
The Sublime Transcendence was a Covenant Supercarrier, the flagship of the Combined Fleet of Righteous Purpose. It was commanded by Imperial Admiral Xytan 'Jar Wattinree.
In August, 2552 the ship picked up a NOVA bomb along with some mining equipment from Reach, implying that either it was present at The Battle of Reach or visited the planet afterward.
A few months later, during the Civil War of the Covenant, the carrier and its fleet were at Joyous Exultation along with as many other Elite-controlled ships as could be found. They met to plan a strike against the Brutes.
The ship and its fleet, and the planet were all destroyed when Kwassass inadvertently triggered the NOVA bomb. However it is speculated that Xytan 'Jar Wattinr may have scaped as Eric Nylund hints that he may still be alive.