(the Swan; abbrev. Cyg, gen. Cygni; area 804 sq. deg.) A northern constellation which lies between Cepheus and Vulpecula, and culminates at midnight in late July. Its origin is uncertain, though it was known to the ancient Greeks, who identified it with one of the forms assumed by Zeus during his amorous pursuits, or with other mythological swans. Its brightest stars were cataloged by Ptolemy (c.