The Cicada sector, also known as Sector 4423, is a sector of space in the galaxy's Alpha or Beta Quadrants. It was rumored to be a region where starships would disappear, never to be heard from again.
In 2269, researchers at the Starfleet Science Center on Rifton compiled sets of data recently received from the Klingon Empire and Romulan Star Empire regarding this sector. (TOS - Log Two novelization: The Lorelei Signal)
Shortly before the next predicted event in 2269, the USS Enterprise was passing close to the sector while escorting a convoy of ore freighters. The starship was assigned to enter the sector and investigate. (TOS - Log Two novelization: The Lorelei Signal)
- The sector was named in the novelization.