The Rosette Nebula
The photograph was made near Taos, New Mexico, USA, in January of 2008 using an SBIG STL-11000M-C2 camera behind a Takahashi FSQ-106 refracting telescope (106 mm aperture, 530 mm focal length) on a Takahashi EM-200 mount. Software used in collecting the data was CCDAutoPilot 3 (session control), CCDSoft 5 (camera control), and TheSky 6 (planetarium software). RoboFocus hardware was used to achieve focus in association with FocusMax (focus-control software). Individual 15-minute exposures were taken, during which precise secondary tracking-corrections were made every 10 seconds using the autoguiding chip within the SBIG camera. The data was evaluated using CCDInspector. Approximately half of the exposures were rejected due to star asymmetry. Acceptable exposures were calibrated (dark-subtracted; normalized using flat-field frames) using CCDStack, and put into register using RegiStar. CCDStack was also used to combine the individual images. Data more than two standard deviations from the mean on a pixel-by-pixel basis was rejected. The combined image contains 105 minutes of light (seven 15-minute exposures) passed through an H-alpha filter, 105 minutes of light (seven 15-minute exposures) through an O-III filter, and 105 minutes of light (seven 15-minute exposures) through an S-II filter. Using Adobe Photoshop, this data was mapped to the red, green, and blue channels, respectively, of a color image. Photoshop was also used to make histogram adjustments to tease out faint detail and reduce background noise.
Marshall H. Edgell is an amateur astrophotographer. This image of the Rosette Nebula is his seventh completed photograph. Dr. Edgell is a Professor of Microbiology & Immunology at the University of North Carolina, Chapel Hill.
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**The Rosette Nebula 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 is closely associated with the nebulosity, the stars of the cluster having been formed from the nebula's matter. The complex has the following NGC designations:
NGC 2237 - Part of the nebulous region (Usually used to denote the entire nebula)
NGC 2238 - Part of the nebulous region
NGC 2239 - Part of the nebulous region (Discovered by John Herschel)
NGC 2244 - The open cluster within the nebula (Discovered by John Flamsteed in 1690)
NGC 2246 - Part of the nebulous region
The cluster and nebula lie 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. The radiation from the young stars excites the atoms in the nebula, causing them to emit radiation, thus 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 ongoing. A survey of the nebula by the Chandra X-ray Observatory in 2001 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 contributors, "The Rosette Nebula," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/wiki/Rosette_Nebula (accessed March 28, 2009).