Sarpedion
Sarpedion was an inhabited planetary system in the Alpha Quadrant. A planet in this system, Sarpedion V, was the headquarters for the Cardassian Twelfth Order in the 2370s.
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 yellow color, which indicated its affiliation with Cardassia Prime. (SNW: "Strange New Worlds")
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 Sarpediion system was in or near to Cardassian space. (PIC: "Maps and Legends", "The Next Generation", "Disengage")
This star system was only mentioned in writing.
According to Star Trek: Star Charts (p. 46) and Stellar Cartography: The Starfleet Reference Library ("Stellar Cartography", pp. 18-19; "Federation Historical Highlights, 2161-2385"), the Sarpedion system was a binary system with a G-class star and a M-class star. According to a map of the Cardassian Union – prepared by an anonymous astrography clerk, from the Cardassian Central Archives, in 2364 – Sarpedion was identified as a Cardassian system.