M42 and the Horsehead Nebula in HaRGB
M42 and the Horsehead Nebula in HaRGB
M42 and the Horsehead Nebula in HaRGB
Throughout the constellation of Orion one can see wide expanses of hydrogen clouds and dusty regions. This image is a widefield image covering approximately 6 by 4 degrees of sky between the Horsehead and Flame Nebula at the bottom left and the Great Orion Nebula in the upper right.

This image combines 4 3/4 hours of narrowband Hydrogen Alpha data with an additional 3.6 hours of color (RGB) data to form an HaRGB composite. To bring out better details within M42, I also blended in 3 1/2 hours of an HDR (High Dynamic Range) detail image taken through my C-8 telescope.

In this image, North is to the left.

Exposure Details
Lens Canon EF 200mm f/2.8L II USM (Base image), Celestron C-8 w/Celestron focal reducer (M42 detail image)
Focal Length 200mm for base image, 1260mm for M42 detail image
Focal Ratio f/3.5 for base image, f/6.3 for M42 detail image
Mount Schaefer GEM - 7 1/2 inch Byers gear
Guiding ONAG On-Axis Guider, Lodestar autoguider, PHD Guiding
Camera Canon 450D - Gary Honis modified
Exposure 72 x180 sec @ ISO 1600 (3.6 hours) for RGB image, 58 x 300 sec @ ISO 1600 (4 3/4 hours) using Astronomik 6nm Ha clip filter, plus 63 x 15 sec @ ISO 200, 59 x 30 sec @ ISO 1600, 56 x 180 sec @ ISO 1600 - about 3 1/2 hours for M42 HDR detail image
Calibration 30 darks, 30 flats, 30 bias
Date December 27, 2011; January 30, 2013; and February 9, 2013
Temperature 45F on 12/27/11, 41F on 1/30/13, 24F on 2/9/13
SQM Reading 21.2 (Bortle 4) until moonrise on 1/30/13, then 19.6 (Bortle 5); 21.15 (Bortle 4) on 2/9/13
Seeing 3/5 on all three nights
Location Pine Mountain Club, California
Software Used Images Plus 4.5 and 5.0 for camera control, calibration, stacking, digital development, multiresolution sharpening, star size and halo reduction, smoothing and noise reduction. Photoshop CS5 used for levels and curves, high pass filter, star shrinking, screen mask invert, unsharp mask, lab color, vibrance, select color, and lens correction. Gradient Xterminator for gradient removal. Carboni Tools for additional noise reduction and smoothing. Focus Magic for focus restoration. HLVG for additional color correction.
Notes I'm quite pleased with this image, other than the Ha data has a bit less time on it than I would prefer. I was able to use noise reduction techniques to make the Ha data reasonably clean, and I think the combination of Ha and RGB worked well overall.

This image was published in the Summer 2014 issue of Amateur Astronomy Magazine in my article entitled "Wide Field Astrophotography - Its Not Just For Beginners".