Rosette nebulae is a Ha region with a circular shape, located close to a giant molecular cloud in Monoceros. Associated with the the nebula, the open cluster NGC 2244 has been formed with material from the nebula

The Rosette Nebula is an emission nebula which is about 5,000 light years away from Earth in the constellation of Monoceros. The nebula spans about 130 light years in diameter and the central cavity of the nebula is about 50 light years in diameter. The symmetric shape of the petals are sculpted by the winds and radiation from the hot young stars in the central region

Like most emission nebulae, however, the central young stars emit high intensity radiation that also excites other types of elements within the cloud to emit at their own characteristic wavelengths. For instance, sulfur (SII) emits at 673.0 nm, and OIII emits at 500.7 nm (most intense) and, to a lesser extent, at 495.9 nm. By using filters that capture SII, Ha, and OIII emission, it is possible to map these colors into the more conventional R, G, and B color palette, respectively. Assigning these narrowband images in this order (highest to lowest wavelengths) to R, G, and B defines the Hubble Palette, which is how the above image was constructed.
Oserve the dark filaments present on the nebula.

Characteristics:
Magnitude: 4.8 (for NGC 2244 star cluster in center)
Distance: 5500 light years
RA: 6h 32m 33s
Dec: 4 degrees 57' 05"
Position Angle: 0 degrees

Image:
Stack: 8x1200sec for each channel of Ha. S2 and O3
Scope: Skywatcher QuatroCF 10" f/4
Camera: Sx-694 trius