- 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)
- Sirius was presumably replaced by a namesake vessel of the same class and registry. As heavy cruisers of the Achernar subclass all had linear warp drive, which wasn't in existence until about 2270, the earlier Sirius would have had the then-extant PB-32 or similar warp nacelles.
During at least the late 2280s, Sirius was assigned to the Starfleet Seventh Fleet. Its CO, until late 2286, was Captain Robert McDonough, Jr. (Starfleet International: USS Sirius, Starfleet Communiqué 17)