The system consisted of a primary and at least five planets. Cardassia Prime (Cardassia II) was the inhabited homeworld of the Cardassians, a warp-capable species. This planet was also the capital of the Cardassian Union. (DS9: "Explorers") The system also included Cardassia I, and the planets Cardassia III, Cardassia IV, and Cardassia V that were colonized by the Cardassians. (DS9: "The Homecoming", "Shadowplay", "Prophet Motive")
In 2375, the location of Cardassia was labeled on a tactical map that was displayed in the wardroom of Deep Space 9. Cardassia was located approximately five light years from the Bajoran system, thirty light years from Starbase 375, and fifty-five light years from Ferenginar. (DS9: "When It Rains...", okudagram)
Later that year, the Dominion began their withdrawal to Cardassia Prime during the waning days of the Dominion War. The Allied Forces planned a risky and costly military operation to end the war by penetrating the system and engaging the Dominion forces stationed in orbit over Cardassia Prime. (DS9: "The Dogs of War")
Background information Edit
"Tactical Display 7624N" was reproduced in legible detail in Star Trek: Star Charts (p. 49).
According to this same book (pp. 36, 42-43), the primary in the system was named Cardassia. Cardassia was a K class star with an absolute magnitude of -1.1, which was a hundred times brighter than Sol. There were a total of eight planets in the system, four of which were inhabited, and two asteroid belts. The system was visited by a Bajoran solar-sail vessel in 1571. Distance between Bajor and Cardassia was 5.25 light years.
According to the RPG book Star Trek: Deep Space Nine - Narrator's Toolkit, the Cardassian sun was a bright red dwarf (M2 V type), the first two planets were class F, Cardassia Prime was the third planet in the system, Cardassia VI and VII were class J gas giants and Cardassia VIII was class G.