SaratogaSkies Jim Solomon's Astropics


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PLN85+4.1 (HII Region)

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Image Details:

Camera: SBIG ST-2000XM
Mount: Astro-Physics 1200GTO
Scope: AP Starfire 160EDF APO Refractor
Configuration: Prime Focus
Additional Optics: n/a (Prime)
Filter: Astrodon LRGB I-Series Filters
Effective Focal Length: 1200mm
Effective Focal Ratio: f/7.5
Exposure: 9 × 32min @ -20°C (Hα); 8 × 8min @ -20°C (RGB)
Total Exposure: 8hrs, 0min
Date: 7/23/2010 (Hα), 8/4/2010 (RGB)
Location: Saratoga, CA, USA
Acquisition: CCD Commander
Focus: FocusMax
Dithering: CCD Commander
Guiding: Self Guided


  • IRIS: Registration, gradient removal
  • JimP: Dark subtraction, Flat field, Kappa-Sigma Stacking, White balance, ASINH stretching
  • Photoshop: Hα and RGB combining, JPG conversion

Image Description:

This is PLN85+4.1, an HII region in the constellation of Cygnus. I thought this was a Planetary Nebula, cuz that’s what TheSky said it was, but upon further review and research, including Anthony Ayiomamitis’ excellent image and writeup, it's just a glowing cloud of HII. Oh well. Hα and RGB combined in Photoshop using the “Lighten” method, which worked better than the other methods I tried. Mouse over for the Hα-only version. A higher-resolution image is also available. North is up.