The Rosette Nebula (NGC 2237-2239) in Hydrogen Alpha

Rosette Nebula in Ha
All Images Copyright Steve Cannistra

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Please click here for a cropped image showing proper motion of selected stars.

Magnitude:  4.8 (for NGC 2244 star cluster in center)
Size: 80' x 60'
Distance: 5500 light years
RA: 6h 31m
Dec: 4 degrees 57' 00"

The Rosette Nebula is a winter showpiece for astrophotographers, as well as for visual observers at low power.  This large emission nebula is located in Monoceros and can be seen in dark locations with the naked eye, especially if viewed through a UHC filter held up to the sky.  The nebula actually consists of several sections (NGC 2237-2239), with a central ladder like star formation known as NGC 2244.  The central stars are young and newly-formed, and their radiation is responsible for excitation of hydrogen atoms within the nebula itself, which in turn emit light in the red.  This is a deep, 4 hour exposure in hydrogen alpha light, which reveals a great deal of faint nebulosity on the periphery of the Rosette, as well as filaments that extend well outside of this field of view.  I compared this image to one taken by the POSS 50 years ago and detected several stars exhibiting proper motion.

Photographic Details:

Date:  November 23, 2007.
Scope:  Takahashi FSQ106 at f5 on the Takahashi NJP Mount.
Autoguider:  SBIG ST-402 with e-finder.
Camera:  STL11K -20C.

Baader 7nm Ha filter (50mm unmounted).
Exposures:  Ha- 12 x 20'.  Total exposure 4 hours.
Conditions:  Temperature was cold, between 15-30 degrees F over the course of the night (focusing every 40 minutes).
Post-processing:  Calibrated, aligned, and Sigma Clip combined in Maxim, followed by DDP in ImagesPlus (IP).  Further processing in Photoshop CS (16 bit format).
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