NGC 2239 (also NGC 2244, Cr 99, Mel 47 and OCL 515) is a magnitude +4.8 open cluster associated with the Rosette Nebula located 5,500 light-years away in the constellation Monoceros. NGC 2239 contains 5 - 8th magnitude young blue stars, which arose about four million years ago. The magnitude 6.0 yellow star 12 Monoceros is a foreground star.
The cluster was discovered by English astronomer John Flamsteed using a refracting telescope on the 17th February 1690.
The cluster was rediscovered by British astronomer John Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflector at Windsor Road, Slough, on the 28th March 1830 and relisted as NGC2239.
Right Ascension 06h 32m 19.0s, Declination Dec +04° 51' 24"