CEPHEUS, in Greek mythology, the father of Andromeda (q.v.) ; in astronomy, a constellation of the northern hemisphere. The star 8 Cephei is the type star of a class of variables called Cepheids (see STAR). It was discovered by Goodricke in 1785. The period is 5.37 days and the range of magnitude is from 3.6 to 4.2. The star "f3 Cephei is also a famous Cepheid variable; although its range of brightness is only 0.05 mag. its variability was detected by Professor Paul Guthnick of Berlin University by photoelectric measurements.