SaratogaSkies Jim Solomon's Astropics

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NGC 6960 (Cirrus 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: Celestron C8-N (8" f/5 Newtonian)
Configuration: Prime Focus
Additional Optics: Celestron/Baader Multi Purpose Coma Corrector (MPCC)
Filter: Hutech Hα Front Filter (HA-FF)
Effective Focal Length: 1000mm
Effective Focal Ratio: f/5
Exposure: 30 x 8min @ ISO 400 (RGB), 30 x 8min @ ISO 1600 (Hα)
Total Exposure: 8hrs, 0min
Date: 9/17/2006 (RGB); 9/19/2006 (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

Processing:

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

Image Description:

This is NGC 6960, aka the Cirrus/Filamentary/Lace-work Nebula and the Western portion of the Veil Nebula, a supernova remnant in the constellation of Cygnus. This image consists of 4hrs of RGB exposure and 4hrs of Hα exposure over two nights.

Unlike my previous Hα+R G B images, in this one I used Hα for Luminance, and the RGB data for color after first blending a smidgeon of Hα into the Red channel. I suppose that makes this technically an Hα:Hα+R:G:B image. Using Hα for Luminance gives a very high contrast result, with added benefit of attenuating the star field which otherwise tends to overwhelm the rather faint nebula. And blending a bit of Hα into the Red channel prevents the salmon-i-zation (salmonella!? <g>) — i.e., the washout — of the red region that results from simple luminance layering in Photoshop. Robert Gendler has an explanation of this technique at his web site. Mousing-over the image shows the RGB stack, without any of the Hα data. Notice how the Veil tends to get lost in the Milky Way star field in that RGB-only image.

A higher-resolution image is also available. North is left.

 
NGC 7331 (Deer Lick Group and Stephan's Quintet)
SaratogaSkies Jim Solomon's Astropics

Search

Latest news

December: Test shots with new scopes/mounts

Dec 21: TMB 80/480 Arrives!

Dec 3: AP1200 Arrives!

Nov 30: TMB 152/1200 Arrives!

Links:

NGC 7331 (Deer Lick Group and Stephan's Quintet)

[Hα+R G B]

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

Image Details:

Camera: Canon Digital Rebel (300D)
Mount: Celestron AS-GT
Scope: Celestron C8-N (8" f/5 Newtonian)
Configuration: Prime Focus
Additional Optics: Celestron/Baader Multi Purpose Coma Corrector (MPCC)
Filter: None
Effective Focal Length: 1000mm
Effective Focal Ratio: f/5
Exposure: 15 x 8min @ ISO 400
Total Exposure: 2hrs, 0min
Date: 9/22/2004, ~12:40am PDT (start)
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: Manual
Guiding: GuideDog via Philips ToUcam Pro II (840k) through Orion ST80 w/ Celestron 2x "Kit" Barlow

Processing:

  • IRIS: Dark subtraction, flat field, registration, normalized Kappa-Sigma stacking, background fit, cropping
  • Photoshop: Levels, image size, cropping, JPG conversion

Image Description:

This is a rich field of galaxies in the constellation of Pegasus. The two major groupings are the Deer Lick Group, in the upper-left, and Stephan's Quintet in the lower-right. NGC 7331 is the largest and most obvious galaxy in this picture, and is the "showcase piece" in the Deer Lick Group. The tracking seemed a bit better in the frames of this image versus previous ones, perhaps due to the insertion of the barlow lens in the guide scope, doubling its effective focal length. This is a composite crop of both galaxy groups at roughly 75% size. A full-resolution image is also available. North is up.