SaratogaSkies Jim Solomon's Astropics


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December: Test shots with new scopes/mounts

Dec 21: TMB 80/480 Arrives!

Dec 3: AP1200 Arrives!

Nov 30: TMB 152/1200 Arrives!


NGC 2174 (Monkey Nebula)

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

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: {4 Hα, 4 OIII, 11 SII} × 32min @ -30°C
Total Exposure: 10hrs, 8min
Date: 2/11/2008 8:08 PM PST, 2/12/2008 7:14 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: Neil's Trick, JPG conversion
  • Neat Image: Noise reduction

Image Description:

This is NGC 2174, aka, the “Monkey Nebula”, an emission nebula and open cluster (NGC 2175) in the constellation of Orion. This is the first image that I scripted entirely with CCD Commander. In fact, I actually left to go play hockey on the first of the two nights I shot this target, thanks to CCD Commander.

Mousing off the image reveals a “Hubble Palette” narrowband image, with R:G:B = SII:Hα:OIII. Mouse-over the image to see a pseudo-“True Color” image, in which those narrowband emission lines are mapped to their approximate color as seen by human vision. Specifically, the red SII and Hα wavelengths are mapped to red, and the aqua (blue-green) OIII wavelength is mapped to both green and blue. Also, a smidge of Hα is added into blue to simulate the Hβ wavelength.

I'm still fighting some star trailing/smearing in my images with the new camera/scope/mount, as yet undiagnosed. Thanks much to Neil Flemming's Trick, I was able to reduce that smearing. A higher resolution image is also available. North is up.