The Rubicun system was an inhabited planetary system. A planet in this system, Rubicun III, was the homeworld of the Edo. This system was near the Strnad system. Both systems were located in a star cluster.
The star cluster contained 3,006 planets that were suitable for colonization. This cluster was claimed by the Edo God, a powerful trans-dimensional being (or beings) worshiped by the Edo, the humanoid inhabitants of Rubicun III.
In 2364, the starship USS Enterprise-D became the first Federation starship to contact the inhabitants of this system. Captain Jean-Luc Picard was requesting shore leave rights for his crew on the planet. (TNG: "Justice")