The Rosette Nebula (also known as 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 lie at a distance of some 5,200 light-years from Earth (although estimates of the distance vary considerably, down to 4,900 light-years.) and measure roughly 130 light years in diameter. The radiation from the young stars excite the atoms in the nebula, causing them to emit radiation themselves producing the emission nebula we see. The mass of the nebula is estimated to be around 10,000 solar masses.
It is believed that stellar winds from a group of O and B stars are exerting pressure on interstellar clouds to cause compression, followed by star formation in the nebula. This star formation is currently still ongoing.
A survey of the nebula with the Chandra X-ray Observatory in 2001 has revealed the presence of very hot, young stars at the core of the Rosette Nebula. These stars have heated the surrounding gas to a temperature in the order of 6 million kelvins causing them to emit copious amounts of X-rays.(Wikipedia)
I took this picture remotely using my telescope T5 at iTelescope in New Mexico from Hamburg.This kind of nebula fits perfectly for narrowband filters imaging.The normal set of filters RGB for color imaging is replaced with a SII Ha OII filters that enchances some parts of the nebula that otherwise are hidden to the human eye.The result is totally different from the colors that we usually see.
The total exposure was about 12 hours.
To compare this image with a normal RGB here is the same target that I took the year before with RGB filters.You can see the difference of details.Of course between the two pictures there is also a difference of exposure.The second one is about 6 hours LRGB.Enjoy