Rosette Nebula: This nebula is a large star-forming region, with a young star cluster. Its color is a result of the ionization of the hydrogen cloud around the star cluster, caused by the high energy of the bright, young stars. As such, its dominant emission is in the hydrogen alpha (Ha) frequency. The nebula actually is made up of NGC2237, NGC2238, NGC2239 and NGC 2246, all of which seem to have been catalogued before it was known that all were part of a large nebula. The small open star cluster NGC2244 can be seen near the center of the nebula; there are other star clusters visually near the Rosette Nebula, but only NGC2244 is known to be physically associated with the nebula. The small, dark globules below and to the left of the center of the nebula (much easier to see in the larger versions of the picture, especially the pure Ha versions) are "Bok globules." This nebula lies about 4,700 light years distant, and is about 140 light years across.

Technical Information:

(HaL)(HaR)GB: 360:195:135:150 (Luminance layer consists of a blending of twelve 30-minute images through an Astrodon Ha filter and the desaturated RGB composite; red channel consisted of a blending of the Ha and red-filtered data; all individual color images were 15-minute exposures through Astrodon filters. All images unbinned).

Equipment: AP130 f/6 Starfire, SBIG STL11000M with internal color filter wheel (Astrodon filter set), on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP, working in concert with TheSky v6.

Processing: All images calibrated (darks and dawn flats), aligned, combined and deconvolved (Ha data only) in CCDStack. Color combine in Photoshop. Finish work (curves and levels, adjustment of contrast; Gaussian blur of color layer) was done in Photoshop CS2.

Location: Data acquired remotely from the Tejas Observatory, located on the grounds of New Mexico Skies, near Mayhill, NM (elevation 7300 feet).

Date: Images taken on many nights from late December 2007 through January 2008.

Pixel scale: 2.1 arcseconds per pixel.

CCD Chip temperature: -25C

Seeing: Generally excellent.

Transparency: Generally good.

Moon Phase: Images taken in all phases of the moon.

Copyright 2008 Mark de Regt

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