NGC2237-9,46 The Rosette Nebula, NGC2244; Monoceros
Astro-Physics 155 EDF (155TCC) f/5.4 refractor
KAF-16803 FLI Proline
Total Exposure Time: 14 hours; SHO 300:270:270 minutes, SII and OII binned 2x2. Stars are RGB.
January 2010; RDO, Moorook, AU
Comments: Discovered by John Flamsteed about 1690. The Rosetta Nebula is a vast cloud of dust and gas, extending over an area of more than 1 degree across, or about 5 times the area covered by the full moon. Its parts have been assigned different NGC numbers: 2237, 2238, 2239, and 2246. Within the nebula, open star cluster NGC 2244 is situated, consisted of the young stars which recently formed from the nebula's material, and the brightest of which make the nebula shine by exciting its atoms to emit radiation.Open cluster NGC 2244 was discovered by Flamsteed about 1690. The nebula, however, was not even seen by William Herschel (who found the cluster); its different parts were discovered only by John Herschel (NGC 2239 = GC 1420 = h 392), Marth (NGC 2238 = GC 5361 = Marth 99), and Swift (NGCs 2237 and 2246); note that while now these numbers are used for describing parts of the diffuse nebula, their original NGC description is quite different (Ref).
This image is processed to show the various colors of the elements Sulfur, Oxygen, and Hydrogen. Here red = SII, green = H-alpha, and blue = OIII. An LRGB version my be seen here.