Perseant Alpha was a star system, located somewhere in the space of the galaxy's Alpha or Beta Quadrants.
History and specifics
In the year 2265, the USS Enterprise traveled through the center of the Perseant Alpha system. It was considered a matter of routine, but several hours later, the ship passed through a temporal disruption that sent it into a different star system 800 years into the past. (TOS comic: "Vibrations in Time")