Cygnus (the swan) is a northern
constellation. It was one of
Ptolemy's 48 constellations, and is also one of the 88 modern constellations. Because of the pattern of its main
stars, it is sometimes called the
Northern Cross (in contrast to the
Southern Cross). It contains a number of bright stars, including the
first magnitude Deneb (α Cyg).
Another of its notable stars is
61 Cygni.
Cygnus also contains the X-ray source Cygnus X-1, which is considered to be one of the most likely black hole candidates.