The independent Omega Sagitta system contained the twin planets that form the Coalition of Madena, Altec and Straleb. This system was located in the Alpha Quadrant. Both worlds were populated by a humanoid race which colonized the planets in the mid-2160s, and now coexist under a tenous but successful treaty. By the mid-24th century, the governments of both worlds were cognizant of the Federation and their starships.
In 2365, one of these starships, the USS Enterprise-D, made a passage through this system on her way to the next mission. (TNG: "The Outrageous Okona")
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.
Straleb, a planet in this system, was on a star chart that was seen in "Generations". The chart depicted the location of planets, stars, and star systems in the Alpha Quadrant. Based on the dimensions of the circles used to mark locations on the star chart seen in "Generations", this planet was located relatively far to the USS Enterprise-D.
Omega Sagitta (Madena, Atlec, Straleb) system was located in the Alpha Quadrant. Primary was a Class F star. Magnitude of this star was +1, which was 100 times brighter than Sol. (Star Trek: Star Charts, United Federation of Planets I)