Rosette Nebula (Caldwell 49)
The Rosette Nebula (Caldwell 49) is a large, circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy. The open cluster NGC 2244 (Caldwell 50) is closely associated with the nebulosity, the stars of the cluster having been formed from the nebula’s matter. The cluster and nebula lay at a distance of some 5,200 light years from Earth (although estimates of the distance vary considerably) and measure roughly 130 light years in diameter.
[description from Wikipedia]