Sector 21527
Sector 21527 was a region of space in the Alpha Quadrant. This sector contained the McAllister C-5 Nebula, the Minos Korva system, and an unspecified asteroid field.

In the mid-24th century, the location of the Cardassian-Federation border running through this sector, and the adjacent sector, was in dispute. The Cardassians believed the placement of this border was the result of a miscalibration error by a reference beacon. According to them, the border should have been 4.7 light years closer to the galactic center.  ()

In 2369, the  rendezvoused with the Cardassian warship Reklar in this sector. In the case of an invasion of this sector by the Cardassians, the Enterprise would be assigned as the command ship.

On board the Enterprise, Captain Edward Jellico and Gul Lemec, representing the Federation and the Cardassian Union respectively, met to negotiate over border disputes. This sector was one of several where there was increased Cardassian activity on their side of the border. During the negotiations, Captain Jellico suggested that the Federation might send starships into the sector for training purposes.

Later, in the aftermath of a failed special operations mission on the Cardassian planet Celtris III in which Captain Jean-Luc Picard had been captured, the Cardassians proposed an exchange. They would hand over Picard and forget about the incident on Celtris III if the Federation immediately withdraw its forces from the sector. ()

In 2370, the  performed tests of new weapons systems in this sector. Later, when the ship's crew was disabled by Barclay's Protomorphosis Syndrome, the Enterprise-D became adrift in this sector. ()

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