The independent Omega Sagitta system contained the twin planets that formed the Coalition of Madena, Altec and Straleb. Both worlds were populated by a humanoid race which colonized the planets in the mid-2160s, and now coexisted under a tenous but successful treaty. By the mid-24th century, the governments of both worlds were cognizant of the Federation and their starships. The mineral tricellite was not available in this system.
The system was initially named the Omega Twelve system, and the planets were members of the Coalition of Madena VI. 
Although Sagitta ("The Arrow") was a real constellation visible from Earth, there was no star with the prefix "omega" since standard nomenclature in this constellation ended with Eta. Furthermore, a hypothetical "omega" star in this constellation should have the name "Omega Sagittae", as the genitive of Sagitta has to be applied.
According to the Star Trek Star Charts, the Omega Sagitta (Madena, Atlec, Straleb) system was located in the Alpha Quadrant. Its primary was a Class F star of magnitude +1, which was 100 times brighter than Sol. (Star Trek: Star Charts, United Federation of Planets I)