SaratogaSkies Jim Solomon's Astropics


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M22 (Globular Cluster)

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: n/a (Prime)
Filter: None
Effective Focal Length: 1000mm
Effective Focal Ratio: f/5
Exposure: 20 x 1min @ ISO 800
Total Exposure: 0hrs, 20min
Date: 7/14/2004, ~1:30am PDT
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: None
Guiding: None


  • IRIS: Dark subtraction, flat frame, registration, Kappa-Sigma stacking, background fit
  • Photoshop: Crop (1/2 x), image scale (1/2 x), JPG conversion

Image Description:

This image was taken under some pretty poor conditions: both the transparency and the seeing were pretty bad, and a ton of dew was accumulating on all of the equipment. It's times like these that I'm glad I have a Newtonian reflector, as an SCT would have been eaten alive by the dew. M22 is a larger and brighter globular cluster than M13, although the latter seems to get all of the attention in the Northern Hemisphere. Perhaps it's because M22 is in Sagittarius and therefore doesn't stand out from the Milky Way stars as well as M13 stands out from its background in Hercules. At the eyepiece, M22 is the better sight in my humble opinion. Of course, both of these pale in comparison to Omega Centauri, which is very difficult to view from mid-Northern Latitudes since it is so far south of the Celestial Equator. North is up.