81 Cancri was a quaternary star system in the Beta Quadrant. The two components of this system were the binary star systems 81 Cancri A/B and 81 Cancri C/D.
Stellar cartography[]
The 81 Cancri system was visible from Earth in the constellation Cancer. It was approximately 66.4 light years from Sol.
In 2259, the location of this system was labeled on stellar cartography charts that were seen on the USS Enterprise's viewscreens. This system's symbol had a blue color, indicating that it was affiliated with the United Federation of Planets. (Star Trek: Strange New Worlds)
In 2324, the location of 81 Cancri was labeled in a chart used during a Section 31 Alpha Team briefing. (Star Trek: Section 31)
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. 81 Cancri was in or near to Federation space. (PIC: "Maps and Legends", "The Next Generation", "Disengage")
In 2401, this system's position was labeled on a star chart used by Captain William T. Riker during his attempt at finding the last known location of the SS Eleos XII. (PIC: "The Next Generation")