(covers information from several alternate timelines)
In 2155, in the mirror universe, Tau Ceti was the system in which the Terran Empire lost twelve ships in a battle against alien rebels. Propaganda had spread that this was a major victory for the Terran Empire, when in fact it was a sign they were losing. (ENT: "In a Mirror, Darkly")
When the universal translator on the USS Discovery malfunctioned, one of the many languages the system translated verbal and written displays into from Federation Standard was Tau Cetian. (DIS: "An Obol for Charon")
Prior to stardate 5718, the USS Enterprise, under the command of Captain James T. Kirk, engaged and defeated a Romulan vessel near Tau Ceti, using the Cochrane deceleration maneuver. (TOS: "Whom Gods Destroy")
In 2293, the location of Tau Ceti in the Milky Way Galaxy was named in a star chart that was in Captain James T. Kirk's quarters aboard the USS Enterprise-A. (Star Trek VI: The Undiscovered Country, production art)
In 2364, the location of Tau Ceti was named in a star chart of a stellar neighborhood with Sol at the center. This chart was stored in the USS Enterprise-D library computer. Later that year, the chart was scanned by Outpost 63. (TNG: "The Naked Now", production art; TNG: "The Last Outpost")
In 2370, Beverly Crusher, when trying to recall name of the Traveler, she recalled to him as "you know that alien from Tau Ceti, the one who could control warp fields with his mind?" (TNG: "Journey's End")
|Tau Ceti system|
|Tau Ceti Prime • Tau Ceti III • Tau Ceti IV|
Background information Edit
According to the Star Trek Encyclopedia (4th ed., vol. 2, p. 375), the Tau Ceti system was some eight light years from Sol.
According to Star Trek: Star Charts (p. 44) and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), the Kaferia (Tau Ceti) system was located in the Alpha Quadrant. The primary was a G-class star. In the late 24th century, this was a Federation system, with Tau Ceti III listed as a member.
According to the novel Enterprise: The First Adventure, Tau Ceti was located along the Romulan Neutral Zone and the inhabitants of Tau Ceti II were widely regarded as possessing great mineralogical expertise, using sapphires as the local currency.