SaratogaSkies Jim Solomon's Astropics


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B33 (Horsehead Nebula)

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Image Details:

Camera: SBIG ST-2000XM
Mount: Astro-Physics 1200GTO
Scope: TMB 152/1200 APO Refractor
Configuration: Prime Focus
Additional Optics: n/a (Prime)
Filter: Astrodon SII, Hα, OIII 6nm Filters
Effective Focal Length: 1200mm
Effective Focal Ratio: f/7.9
Exposure: {5 SII, 5 Hα, 5 OIII} × 32min @ -20°C
Total Exposure: 8hrs, 0min
Date: 2/7/2008 8:19 PM PST, 2/8/2008 7:20 PM PST (Start)
Location: Saratoga, CA, USA
Acquisition: CCD Commander
Focus: FocusMax
Dithering: CCD Commander
Guiding: Self Guided


  • IRIS: Registration
  • JimP: Dark subtraction, Flat field, Kappa-Sigma Stacking, White balance, ASINH stretching
  • Photoshop: JPG conversion
  • Neat Image: Noise reduction

Image Description:

This is B33, aka, the “Horsehead Nebula”, a dark nebula silhouetted against the bright nebula IC 434 in the constellation of Orion. Compare this closeup with the true color, wide-field, DSLR image, which shows the Horsehead in context with the bright belt star, Alnitak.

Mousing off the image reveals a “Hubble Palette” narrowband image, with R:G:B = SII:Hα:OIII. Mouse-over the image to see the H-alpha only image in grayscale. A higher resolution image is also available. North is left.