Planet X

Planet X is a planet in Ultima II. Castle Barataria (where Father Antos can be found) and Mary's Town are both located here as well.

In New San Antonio the Stranger learned that, in order to get the Force Field Ring, the blessing of Father Antos was needed before the old man who owned the ring would sell it. Using a space ship in the time of Aftermath, the Stranger warped to Planet X and found Castle Barataria, getting Father Antos' blessing to receive the ring.

Trivia

 * Planet X is not on the space chart found in the documentation.
 * The coordinates of Planet X are 9,9,9.
 * Interesting enough, Castle Barataria has the same name as a castle in The Lands of the Feudal Lords in Ultima I.