CASSIOPEIA

(CAS) in astronomy, a constellation of the northern sky, easily recognized by a group of five bright stars forming a slightly irregular W. It lies at one hour right ascension (the coordinate of the celestial sphere analogous to longitude on the Earth) and 60 north declination (angular distance north of the celestial equator). Tycho's nova, one of the few recorded supernovae in the Galaxy, appeared in Cassiopeia in 1572.