SaratogaSkies Jim Solomon's Astropics


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NGC 1499 (California Nebula)

[Hα+R G B]

Mouse-over to see annotations. (Requires Javascript) Click to see high-res version.

Image Details:

Camera: Mofidied Canon Rebel XT (350D): Hutech Type I Filter Replacement
Mount: Celestron AS-GT
Scope: Orion ED80 (80mm f/7.5 APO Refractor)
Configuration: Focal Reduced
Additional Optics: William Optics 2" APO 0.8x Reducer/Field Flattener
Filter: Hutech Hα Front Filter (HA-FF)
Effective Focal Length: 480mm
Effective Focal Ratio: f/6
Exposure: 26 x 8min @ ISO 800 (RGB); 33 x 8min @ ISO 1600 (Hα)
Total Exposure: 7hrs, 52min
Date: 1/9/2007 (RGB); 1/8/2007 (Hα)
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: GADFly 1.0.5
Guiding: GuideDog via Philips ToUcam Pro II (840k) through Orion ST80 w/ Celestron 2x "Kit" Barlow


  • IRIS: Dark subtraction, registration, gradient removal
  • JimP: Flat field, Kappa-Sigma Stacking, White balance, ASINH stretching
  • Photoshop: HαRGB combination, Levels, cropping, JPG conversion

Image Description:

This is NGC 1499, aka the California Nebula in the constellation of Perseus. (Tilt your head to the right if this nebula doesn't resemble the State of California in the USA.) Unlike previous HαRGB composites, I did all the combining of the Hα and RGB in Photoshop. First, I used the Hα in “Linear Dodge” mode to pre-saturate the Red (33%) and Blue (3%) channels, and then used the Hα as Luminance at 50%. The result looked better than I could do with my own software in “trial and error” mode.

Mouse-over the image to see the Hα image in grayscale. Mouse-off to see the HαRGB composite. A higher-resolution image is also available. North is up.