SaratogaSkies Jim Solomon's Astropics


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NGC 2244 (Rosette Nebula)

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Image Details:

Camera: Mofidied Canon Rebel XT (350D): Hutech Type I Filter Replacement
Mount: Celestron AS-GT
Scope: Orion ED80 (80mm f/7.5 APO Refractor)
Configuration: Focal Reduced
Additional Optics: William Optics 2" APO 0.8x Reducer/Field Flattener
Filter: None
Effective Focal Length: 480mm
Effective Focal Ratio: f/6
Exposure: 30 x 8min @ ISO 1600
Total Exposure: 4hrs, 0min
Date: 2/22/2006 7:40:04 PM PST (start)
Location: Saratoga, CA, USA
Acquisition: DSLRfocus
Focus: DSLRFocus
Dithering: GADFly 1.0.5
Guiding: GuideDog via Philips ToUcam Pro II (840k) through Orion ST80 w/ Celestron 2x "Kit" Barlow


  • IRIS: Dark subtraction, registration, gradient removal
  • JimP: Flat field, Kappa-Sigma Stacking, White balance, ASINH stretching
  • Photoshop: Levels, cropping, JPG conversion

Image Description:

This is NGC 2244 et. al., aka, the Rosette Nebula in the constellation of Monoceros. The catalog numbers of this object are in dispute (cf Haluk Akcam's analysis), though most seem to agree that NGC 2244 refers to the Open Cluster of stars in the center of the nebula, and NGC 2246 et. al. refer to the nebula itself.

The Rosette Nebula is extremely faint, so I upped the individual exposures (8min) and cranked the ISO (1600) in order to better resolve the nebula. Close inspection reveals that the faintest traces of nebulosity are still below the read-noise floor of the camera. The cost of these long exposures/high ISOs is, of course, a washout of the color in the brightest stars. A worthwhile tradeoff IMO.

A higher-resolution image is also available. North is up.