USS Sirius (NCC-1744) was a Constitution-class (Achernar subclass) heavy cruiser active in Starfleet through at least 2292. Gregory Calkins, later a fleet admiral, commanded the Sirius at some point in the 2250s. (Star Trek II Biographies) In the continuity of Star Trek II Biographies, Lieutenant Spock was an assistant science officer on the Sirius under Calkins. In the mid-2260s, Lieutenant Alisü Godibatz was chief of security aboard Sirius and evacuated the crew to a nearby planet during a Klingon attack before the ship was destroyed. (Starfleet Supplemental Communiqué 1:9)