M42 is the Great Nebula in Orion.

The Orion Nebula complex is undoubtedly one of the most famous and beautiful areas of the entire night sky. It is easily visible to the unaided eye from a dark location as a patch of brightness surrounding Theta Orionis, the middle star in the sword of Orion the Hunter, the constellation which dominates the winter night sky.

Located about 1,350 light years away, the nebula glows red predominantly from the light of hydrogen gas excited by energetic newly formed stars in the heart of the nebula. It is the nearest star forming region to our own star, the Sun.

Exposure Data

• Lens: Astro-Physics 130EDT f/8 Triplet Apochromatic Refractor
• F/stop: f/6 with 0.75x matched Telecompressor
• Exposure: Composite of 4 sets of exposures:
  
  • 6 x 600 seconds
  • 4 x 150 seconds
  • 4 x 30 seconds
  • 4 x 8 seconds
• Mount: Polar-aligned tracking equatorial mount, auto-guided
• Camera: Canon EOS 20Da DSLR
• Mode: RAW
• ISO: 400
• White Balance: Custom
• In-Camera Noise Reduction: Off
• Filter: None
• Temp: 34F
• Time 3:00 a.m. EST
• Date October 30, 2005
• Location: Belleplain, NJ
• Calibration: Darks: 16 x 10 min + bias frames to create a scalable master dark frame for the 150 and 600 second exposures. Auto-dark calibrated each light frame in Images Plus v2.75beta.
• Processing: Automatic Image Set Processing in Images Plus v2.75 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 dark. The light frames were then Bayer interpolated to convert them to color images. The light frames were then registered and aligned in Images Plus. The light frames for each exposure set were then composited together and "stacked" in Images Plus using min-max excluded as the method. A non-linear curve was then applied to these frames. The 4 exposure set composites were then combined with layer masks into a 16-bit TIFF master light 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 and the image rotated in Photoshop CS2. Noise Ninja was used to reduce noise in the image. Noel Carboni's Astronomy tools star-size reduction action was applied.