SaratogaSkies Jim Solomon's Astropics


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IC 1318 (Gamma Cygni Nebula)

Image Details:

Camera: Canon Digital Rebel (300D)
Mount: Celestron AS-GT
Scope: Celestron C8-N (8" f/5 Newtonian)
Configuration: Prime Focus
Additional Optics: Celestron/Baader Multi Purpose Coma Corrector (MPCC)
Filter: None
Effective Focal Length: 1000mm
Effective Focal Ratio: f/5
Exposure: 8 x 8min @ ISO 400
Total Exposure: 1hrs, 4min
Date: 9/6/2004, ~11:50pm PDT
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, registration, Kappa-Sigma stacking
  • Photoshop: Levels, image size, JPG conversion

Image Description:

This is IC 1318, a patch of nebulosity around the bright star Gamma Cygni (aka Sadr) in the constellation of Cygnus. In case you're wondering, Gamma Cygni is the bright star in the center of the photo. The full-size image shows excellent off-axis coma correction, indicating that the MPCC performs pretty well when the optics are well collimated.

A new-and-improved set of Flat Field frames helped in the processing of this image. The Flat Field giving the most pleasing result was generated as follows:

  • Set of 16 individual frames, median-combined
  • Captured between 5min and 8min after sundown
  • 1/8 second exposures @ ISO 100
  • DEC equal to my latitude
  • Hour Angle equal to two hours East of the Meridian
  • Tracking on during the exposure, but off between exposures (this allows the median-combine to remove any stars captured in the individual frames)

This is the full frame, scaled for display on the web. North is up.