SaratogaSkies Jim Solomon's Astropics


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!


M3 (Globular Cluster)   [obsolete]

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: Negative Projection (Barlowed)
Additional Optics: Celestron/Baader Multi Purpose Coma Corrector (MPCC)
Filter: None
Effective Focal Length: 2250mm
Effective Focal Ratio: f/11.1
Exposure: 12 x 2min @ ISO 800
Total Exposure: 0hrs, 24min
Date: 6/1/2005 10:40:31 PM 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


  • IRIS: Dark subtraction, Flat field, Best frame selection, Registration, Gradient removal, Richardson-Lucy deconvolution, LRGB computation, ASINH stretching
  • JimP: RGB to Luminance conversion (NTSC weighting), Kappa-Sigma stacking, White balance
  • Photoshop: Levels, cropping, JPG conversion

Image Description:

This is M3, a Globular Cluster in the constellation of Canes Venatici. This was taken on a night of better seeing and less wind than the night of my M13 image. Even though most of the frames showed tracking and flexure problems, the 12 that remained gave a nice stack, and Richardson-Lucy deconvolution tightened it up a bit further. This is the full frame, shrunk for display on the web. The full-resolution image is also available. North is up.