Sirius was a binary star system consisting of the stars Sirius A and Sirius B. This inhabited system was located approximately eight light years from the Sol system. (TNG: "The Naked Now" production art)
In 2293, the location of Sirius in the Milky Way Galaxy was labeled in a star chart that was in Captain James T. Kirk's quarters aboard the USS Enterprise-A. (Star Trek VI: The Undiscovered Country, okudagram)
In 2364, the location of Sirius was labeled in a star chart of a stellar neighborhood with Sol at the center. This chart was stored in the USS Enterprise-D library computer. Later that year, the chart was scanned by Outpost 63. (TNG: "The Naked Now", production art; TNG: "The Last Outpost")
The Sirius group was mentioned in Gene Roddenberry's original Star Trek pitch in one of the suggested story lines. In the storyline "Kentucky, Kentucky," the Sirius group was home to an Earth colony for fifty years. This colony was attacked by viking-like savages and reduced to a "frontier" log-fort life. They were regrouped and led by Captain Robert April when the SS Yorktown visited the colony.
The chart naming stars within 20 light years of Sol was originally drawn by Rick Sternbach for the Star Trek Spaceflight Chronology in the late 1970s. Found on page 77, this chart showed Earth commercial and exploration routes after the use of warp drive began. Sirius was a destination on an exploration route.
According to Star Trek: Star Charts (pg. 45), Sirius, also known as Alpha Canaris Majoris, was located in or near Federation space, in the Beta Quadrant. It was a binary star system. Sirius A was an A-class star with a magnitude was +1, which was a hundred times brighter than Sol. Sirius B was also an A-class star.