Sigma Draconis VIII was the eighth planet in the Sigma Draconis system. This planet's orbit brought it close to the orbital path of Sigma Draconis IX. This was one of six planets in this system that was not classified as M class. (TOS: "Spock's Brain")
According to the Star Trek: Star Charts (pgs. 19, 44), Sigma Draconis IX was located in Sector 004 (Sigma Draconis sector).