NGC 643 (also ESO 29-SC50) is a magnitude +12.3 open star cluster located in the constellation Hydrus.
The open cluster was discovered by British astronomer John Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflecting telescope at Feldhausen, Wynberg in Cape Town, on the 18th September 1835.
Right Ascension 01h 35m 00.7s, Declination -75° 33' 24"
