
Locator logo showing the galaxy's Alpha and Beta Quadrants.
The Horus sector was a region of space, a sector location on star charts used by the Federation in the 24th century.
History and specifics

The Z'Tarnis Nebula.
The Horus sector was one of several space regions within the Z'Tarnis Nebula, a Mutara class nebula at the border of the Romulan Star Empire's Neutral Zone with the Federation, somewhere in the galaxy's Alpha or Beta Quadrants. (TNG video game: A Final Unity)