Beta Zeta was an inhabited planetary system in the Alpha Quadrant. One of its planets was Betazed, the homeworld of the warp-capable Betazoids. In the late 2250s, this species had or was in the process of being inducted into the United Federation of Planets.
In 2259, the location of this system was labeled on a stellar cartography chart that was seen on the USS Enterprise's ready room viewscreen. This system's symbol had a blue color, indicating that it was affiliated with the United Federation of Planets. (SNW: "Strange New Worlds", "Children of the Comet", "Spock Amok")
The system's location was labeled in a Federation star chart that was in Fleet Admiral Kirsten Clancy's office at Starfleet Headquarters in 2399 and on the bridge of the USS Titan-A in 2401. The Beta Zeta system was in or near to Federation space. (PIC: "Maps and Legends", "The Next Generation", "Disengage")
In 2401, the location of Beta Zeta was labeled on a star chart that was on the bridge of the USS Titan. (PIC: "The Next Generation")
This star system was only mentioned in writing.