A diffuse nebula in Monoceros over 1° wide, surrounding a 5th-magnitude star cluster, NGC 2244. The nebula is so named because it resembles a rosette. The brightest parts of the nebula have their own NGC numbers: NGC 2237, 2238, 2239, and 2246. The associated star cluster, consisting of stars of 6th magnitude and fainter, spans about ½°. The nebula and cluster lie 5000 l.y. away.