NGC 2309 (also OCL 557 and Collinder 122) is a magnitude +10.5 open cluster located in the constellation Monoceros. The cluster was discovered by German-British astronomer William Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflector on the 4th March 1785.
Right Ascension 06h 56m 03.6s, Declination -07° 10' 28"
