SaratogaSkies Jim Solomon's Astropics


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M20 (Trifid Nebula)   [obsolete]

Image Details:

Camera: Canon Digital Rebel (300D)
Mount: Celestron AS-GT
Scope: Celestron C8-N (8" f/5 Newtonian)
Configuration: Prime Focus
Additional Optics: n/a (Prime)
Filter: None
Effective Focal Length: 1000mm
Effective Focal Ratio: f/5
Exposure: 24 x 1min @ ISO 800
Total Exposure: 0hrs, 24min
Date: 7/11/2004, ~1:30am PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: None
Guiding: None


  • IRIS: Dark subtraction, flat frame, registration, and Kappa-Sigma stacking
  • Photoshop: Noise reduction, crop (1/2 x), image scale (1/2 x), JPG conversion

Image Description:

Another stunning object in the "summer" Milky Way. This is the Trifid Nebula, yet another gem in the constellation of Sagittarius. This is a Sigma stack of the best 24 of the 30 frames (the remaining 6 showed trailing/smearing due to tracking error). Interestingly, "dark subtraction" yielded a worse image than just stacking the un-dark-subtracted frames. I need to look into this. North is up.