61 Cygni

61 Cygni was a star system used by the Darklings as an enclave following their expulsion from Yuggoth by the Tzun circa 23,000 BC. (PROSE: First Frontier)

Behind the scenes
The information on 61 Cygni in PROSE: First Frontier is a reference to the episode Killer of Blake's 7, where 61 Cygni is an area known as the "Darkling Zone" which is home to an isolated alien civilisation that infects human explorers with a virus designed to kill anyone who's been to deep space.