Musca

Musca (abbreviation Mus, genitive Muscae) is one of the minor southern (declination -70 degrees) constellations. It contains the soft X-ray transient Nova Muscae 1991. Nova Muscae 1991 which is a binary star where one of the stars is a black hole. During the 1991 outburst, radiation produced by positron annihilation was detected from Nova Muscae.