Gamma 7 sector was a region of space. This sector contained the Federation planet Gagarin IV.
In 2365, the USS Lantree was assigned to the Gamma 7 sector, when her entire crew fell victim to a mysterious disease. (TNG: "Unnatural Selection")
In the episode's script, the
Lantree was assigned to Gamma seven seven. For the filmed episode, the second "seven" was changed to "sector".