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Pinwheel Galaxy - M101

 

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Scope: C8  f/6.4, Location: Dos Picos Park, Ramona CA,   16 March 2009 (Lum and Ha), 23 March, 2009 (RGB) Camera: Artemis285

Exposure: 10 x 8 minutes Luminance exposures (1x1) with IR block, 5 x8 minutes Ha exposures (1x1), 8 x 3 minutes RGB exposures (2x2).

Processing: Images were captured Artemis Capture (as FITs). Aligned/stacked and dark subtracted in Astroart with Average Combine and Sigma Combine. Luminance exposures were average stacked (best SNR). Sigma combine stacking was used to remove pixel and satellite artifacts. Average combine was merged with sigma combine as a layer selecting only those artifact pixels on the average stack.. H-Alpha and Color exposures were only Sigma Combine stacked. All channels were scaled and rough color balanced in Astroart.  Central Gradient was removed on all channels in Astroart. Channels were co-registered in Astroart. The 8 minute IR block exposures were used for the main luminance construction with level adjustments and curves to bring out object features.   LRGB combine was done in Photoshop. G2V  factors applied to color channels.  Background noise reduction was applied in Photoshop.  Selective sharpening was applied to galaxy features. Final touches and color balance in Photoshop. Final Image size is approximately 1392x1040.

North is up in this image. The image was guided for all exposures. M101, located in Ursa Major, is somewhat irregular in that the core appears to be off center in the spiral. Despite the apparent imbalance, M101 is considered a fine example of the "Grand Design" type of galaxy. M101 contains many gaseous knots in its arms as can be seen in this image. The H-Alpha filter exposures tend to highlight some of these knots. M101 is about 25 million light years distant from earth. This image is a close in image; a wider field image that shows the full extent of the spiral arms can be seen here  replaces an earlier image that can be seen here.  Horizontal FOV is 24'.

Image center is approximately - Equatorial 2000: RA: 14h 03m 12s Dec: +5420'58"

 

All images and content remain the property of Jim Thommes - copyright 2003 - 2012

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