(covers information from several alternate timelines)
The USS Relativity (NCV-474439-G) was a 29th century Federation Wells-class starship operated by Starfleet. This timeship was commissioned at the University of Copernicus, and was under the command of Captain Braxton. The vessel was equipped with powerful sensors capable of scanning throughout spacetime, and a temporal transporter capable of beaming an individual to virtually any point in space and time.
The Relativity was involved in a mission to avert the destruction of the USS Voyager, which was destroyed in 2375 by a temporal disruptor. Seven of Nine and Captain Kathryn Janeway were recruited from that time period to identify and apprehend the person responsible. It was eventually discovered that the saboteur was, in fact, a future version of Captain Braxton, who held the Voyager crew responsible for his eventual forced retirement. In response to this revelation, Braxton's first officer, Lieutenant Ducane took command of the ship, and successfully completed the mission to save Voyager from destruction. (VOY: "Relativity")
The Relativity's dedication plaque listed members of the Temporal Integrity Commission and contained a quote from E.M. Rauch: "The only reason for time is so that everything doesn't happen all at once."