61 Cygni was a star system. This system consisted of binary companion stars, 61 Cygni A and 61 Cygni B. This star was located near Sol, Tau Ceti, Sirius, and Alpha Centauri. It was located in the Alpha Quadrant.
On several occasions in 2364, viewscreen readouts aboard the USS Enterprise-D showed the location of the 61 Cygni A and B stars, in the form of a star chart from the Enterprise-D library computer. (TNG: "The Naked Now", "The Last Outpost", "Conspiracy")
The star chart naming stars within 20 light years of Sol was drawn by Rick Sternbach for the Star Trek Spaceflight Chronology in the late 1970s. Found on page 77, this chart showed Earth commercial and exploration routes after the use of warp drive began. 61 Cygni was the destination on an exploration route. The stars Alpha Centauri, Sol, Sirius, and Tau Ceti were identified on "The Explored Galaxy" wall chart as being located in the Alpha Quadrant.
According to Star Fleet Technical Manual, the United Planets of 61 Cygni was one of the founding members of the Federation. According to The Worlds of the Federation, the fifth planet in the system was the homeworld of the Tellarite race.
61 Cygni (Tellar): This was a binary star system. Teller A was a K-class star with a magnitude of +5, which was the same brightness as Sol. Teller B was a K-class star. There was an inhabited planet, Tellar Prime, in this system. The planet was the homeworld for the Tellarites, a warp capable humanoid species. The system was located in Sector 007 (Tellar Sector) in the Alpha Quadrant. (pgs. 19, 36)