Sector 21166
Sector 21166 was a region of space in the Beta Quadrant. The Klingon system Beta Penthe was located in this sector. 

In 2293, the chart Starship Mission Assignments listed Starfleet starship deployments in a range of sectors, starting at Sector 21166. This chart was on display in the bridge of the . 

That same year, after the capture of James T. Kirk and Leonard McCoy by the Klingons, Starfleet Intelligence proposed a special operations mission code-named Operation Retrieve which had the directive to rescue both Starfleet officers from Rura Penthe. In this operation, the , escorted by the  and the , would head the rescue mission. In addition, , , and  were listed as the ships on station. ( set artwork)

In 2367, the chart "Starfleet Operations – Sectors 21166-23079" listed the activity of Starfleet starships in in a range of sectors, starting at Sector 21166 and ending at Sector 23079. This chart was on display in the bridge of the . ( okudagram)

Later that year, the star chart "Starfleet Operations – Sectors 21166-22079" was on display in the tactical area of the Enterprise-D. This chart was used by Worf and  as they discussed the attacks on neutral freighters committed by Klingon rebels who were fighting for the independence of their colony on the planet Krios. ( okudagram)

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