M42, commonly called the Orion Nebula, is a fascinating region of star formation. In this image, most of the stars are brand new "baby" stars typically on the order of ten to a few hundred thousand years old. Astronomers have identified around 700 stars that are formed from this nebula. In this photo, you can easily see the "Trapezium" - the bright asterism of 6 stars in the center of the nebula (of which 4 are visible in this image).

The red areas in the nebula are mostly shining from hot hydrogen gas in the nebula. The blue areas are mostly dust that reflects the light of the hot blue stars. One of these areas is at the top of the image - the circular nebula above the main nebula is actually another Messier object - M43.

This complex is easily visible with the naked eye. When looking at the constellation Orion, M42 and M43 are part of Orion's "sword" just south of the 3 bright stars that make up Orion's belt. To the unaided eye, the sword clearly appears fuzzy - not sharp like a star.

In this image, North is up. This image is cropped to 96% of the original frame.

Exposure Details
Lens	Celestron C-8 SCT with Celestron focal reducer
Focal Length	1260mm
Focal Ratio	f/6.3
Mount	Schaefer GEM - 7 1/2 Byers Gear
Guiding	80mm f/11 guidescope with PHD Guiding
Camera	Canon 450D - Gary Honis modified
Exposure	63 subexposures of 15 sec @ ISO 200, 59 x 30 sec @ ISO 1600, 56 x 180 sec @ ISO 1600 - about 3 1/2 hours total
Calibration	30 darks, 30 flats, 30 bias
Date	December 27, 2011
Temperature	45F
SQM Reading
Seeing	3 of 5
Location	Pine Mountain Club, California
Software Used	Images Plus 4.5 for camera control, calibration, stacking, digital development, multiresolution sharpening, smoothing and noise reduction. Photoshop CS5 used for levels and curves, color correction, high pass filter, star shrinking, saturation adjustments, lab color, smart sharpen, screen mask invert, match color, HDR toning and multilayer luminance combining. Gradient Xterminator for gradient removal. Carboni Tools for additional saturation adjustments, noise reduction, and smoothing. HLVG for additional color correction.
Notes	This is the first time I composited images (combining more than one image to make a single image). While M42 is very bright and easy to image, it has an extremely wide range of brightness levels (high dynamic range). Because of this, its not possible to capture the faint outer regions without dramatically overexposing the interior. Conversely, if you expose for the interior regions (the Trapezium), you won't capture the faint outer nebulosity. In this image, I combined 15, 30, and 180 second exposures. By layering these images together and using some masks, I was able to maintain details from the inner core to the outer edges. I believe the technique worked very well, and I'm quite proud of this astrophoto. In this, my second processing of this image, I used my DSLR-LLRGB method to bring out some better details, improve color saturation, and reduce the noise. The prior processing of this image is HERE