Answer:
During the attack on Pearl Harbor on December 7, 1941, the aircraft carriers of the United States Pacific Fleet were not present in the harbor. They were fortunately out at sea on various missions and were not at Pearl Harbor during the attack.
However, there was one aircraft carrier, the USS Enterprise (CV-6), that was returning to Pearl Harbor from Wake Island during the time of the attack. The Enterprise arrived at Pearl Harbor shortly after the attack had ended.
So, to answer your question: The USS Enterprise (CV-6) was the aircraft carrier that was at Pearl Harbor shortly after the attack, though it was not present during the attack itself.