B33 - The Horsehead Nebula

Location: Comanche Springs, 3RF dark sky site near Crowell, Texas

Date: October 26, 2005

Seeing: 9/10

Transparency: 8/10 (mag. 7 skies)

Temperature: 32 degrees F (-25 degrees C on camera)

Scope/Mount: 12.5" RCOS RC @ f/9 and Paramount ME

Camera: SBIG STL-11000M astro CCD camera

Exposure Info: LLRGB image; 160:50:40:60 RGB (20 minute subexposures for L, 10 minute subexposures for RGB, color binned)

Processing Information: Acquisition with CCDSoft. Calibration (darks/flats), registration, gradient removal, and RGB channel combine in MaxIm DL 4 (average combine). LRGB and LLRGB combine, color balance, levels/curves, high pass sharpening, and noise removal and local contrast enhancement (Noel Carboni's Astronomy Tools) in Photoshop CS.

Exposure Notes: One of the more difficult objects I've shot, simply because of the havoc wreaked by the bright star Alnitak just off the frame to the left. Philosophically, it poses a dilemma…attack the gradient, leaving the viewer with the question of why the red channel is weaker compared to the other channels -or- preserve the gradient, making it more obvious that something lurks outside the frame impressing itself on the landscape? For this image, I chose a mixture of both philosophies. The original data is heavily biased to the blue, so strengthening of the red channel and removal of most of the blue gradients were required; however, leaving some of the diffraction spikes/flares from Alnitak gives reference to its presence.