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B33, The Horsehead Nebula

The Horsehead Nebula, B33, is the dark nebula in front of the bright red emission nebula IC 434.

Along with the Orion Nebula, these nebulae near the Horsehead are part of a very large complex that is a stellar nursery where stars are forming out of the dust and gas. Located about 1,500 light years away, this complex is the closest star forming region to our own solar system.

The Flame Nebula, NGC 2024, is to the lower left of Alnitak, Zeta Orionis, the easternmost star in the three distinctive stars in the Hunter's belt of Orion, and the brightest star in this photo.

Exposure Data
  • Lens: Astro-Physics 130EDT f/8 Triplet Apochromatic Refractor
  • F/stop: f/6 with 0.75x matched Telecompressor
  • Exposure: 4.5 hours total exposure:
    • RGB: 18 x 600 seconds
    • Ha: 9 x 600 seconds
  • Mount: Polar-aligned tracking equatorial mount, auto-guided
  • Camera: Canon EOS 20Da DSLR
  • Mode: RAW
  • ISO: RGB: 800, Ha: 1600
  • White Balance: Custom
  • In-Camera Noise Reduction: Off
  • Filter: RGB:IDAS LPS, Ha: Lumicon Hydrogen-alpha cut filter
  • Temp: RGB: 40F, Ha: 33F
  • Time: 4:34 a.m. EDT, 3:48 a.m. EDT, 1:38 a.m. EST
  • Date October 22, Oct 26, Nov 25 2006
  • Location: Belleplain, NJ
  • Calibration: Dark frames: RGB: 24 x 600 seconds at ISO 800 40F, Ha: 36 x 600 seconds at ISO 1600 at 40F, plus bias frames, darks auto-scaled in Images Plus v 2.8
  • Processing: Automatic Image Set Processing in Images Plus v2.8 where all light CR2 raw files were converted to 16-bit linear TIFF files with No White Balance, Color Filter Array as the white balance type, then calibrated with the master darks. The light frames were then Bayer interpolated to convert them to color images. The light frames were then registered and aligned in Registar. The light frames for each exposure set were then composited together and "stacked" in Images Plus using min-max excluded as the method and saved as a 16-bit TIFF master light image. A non-linear curve was then applied to these frames. The red channel from the hydrogen-alpha image was then substituted into the RGB color image. Color balance was then adjusted with levels and curves modifications in Photoshop CS2. An SMI enhancement was applied to bring out the really faint detail. A series of masked high-pass filtered softlight layers were used to increase local contrast. Color saturation was increased in Photoshop CS2. Noise Ninja was used to reduce noise in the image. Noel Carboni's Astronomy tools star-size reduction action was applied. The image was then resized and saved as a JPEG for web display.

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