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The Horsehead Nebula
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About this Object: |
One of the most famous
objects in the sky, the Horsehead Nebula is a dark nebula only seen
because of the reflection nebula, IC 434, that shines brightly behind
it. It carries the designation of Barnard 33, one of many dark nebulae
in the Barnard catalog. To the lower left in this picture is another
emission nebula, NGC 2023. The Horsehead itself cannot be seen visually
except by larger aperture scopes in very dark skies. Medium aperture
scopes and some smaller scopes with fine optics can make out the shape
of the Horsehead with the aid of a Hydrogen-Beta filter, but that is the
exception to the rule. A filter, dark skies, and big aperture gives you
the best opportunity, but this is primarily a photographic object, and a
great one at that! |
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- perserve 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.
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The
Horsehead Nebula, Barnard 33, in detail. |
Astronomi
Nebula Resimler
Astrophotography
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