Trekipedia

Quadrants

One quarter of the galaxy. The four quadrants were designated by the Greek letters Alpha, Beta, Gamma, and Delta, and were arbitrarily divided using Earth as a reference point. As a result, Earth, and the sector it occupied, fell in the Alpha Quadrant, while the sector containing Vulcan and Andoria fell in the Beta Quadrant. The Gamma and Delta Quadrants remained largely unexplored through the 25th century, though knowledge of those regions was greatly increased thanks to the Bajoran wormhole and the U.S.S. Voyager NCC-74656, respectively.^[1]

Quadrants were further divided into numbered Subquadrants and Sector Zones. The intersection of a subquadrant and a sector zone resulted in a cube-shaped Sector Grid, which was 5000 light years long and 3600 light years high along the galactic plane. Each sector grid was then divided into a cubic grid of 100 Sector Quads, which were then further broken down into 900 or more roughly cubical Sector Blocks, each measuring 100x100x80 light years. Finally, sector blocks were divided into 100 Sectors, each measuring 20 cubic light years. Sector numbers were a nine-digit sequence with the first two digits representing the sector grid, the second two digits representing the sector quad, the next three digits representing the sector block, and the final two digits representing the sector proper. Prior to the mid-24th century, sector quads were commonly, though erroneously, referred to as “quadrants.” This practice fell into disuse, however, due to the widespread confusion it often generated.^[1]

References

• ^[1]STSC: Star Trek: Star Charts