Cylon Capitals are XL sized ships that consist of Basestars and Carrier support ships. Only two Basestars were trapped in the Veil Sector after the Battle of the Resurrection ship.
Available Capital Ships:
The Surtur is a Carrier class ship that can carry a number of Strike class ships and support them in combat.
The Carriers were reworked in June, 2014. The previous version of the Surtur can be found here:
The Secondary Basestar can be temporarily commanded by requesting command to Number One - Cavil, in exchange for a large sum of Merits.
Unavailable Capital Ships:
The Main Basestar resides in 242 Apollid where it protects and coordinates the activity of the Cylon Fleet. It cannot be used in any way by players.