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M21 in Sagittarius


Scope: C8 f/2.8; Location: Del Mar CA;  1 Sept. 2004; Camera: ToUcam SC3

Exposure: 16 x 12 sec  and 16 x 4 sec Luminance exposures with Baader IR Block Filter; 15 x 8 sec RGB 

Processing: All exposures captured  in K3CCDTools. Alignment and stacking was done with Registax and saved as FITs. LRGB channels were co-registered in Astroart. Luminance and Color channels were scaled and rough color balanced in Astroart.  The shorter Luminance exposure was combined with the longer one to reduce star bloat in the Luminance construction. Final LRGB combine was done in Photoshop using Luminance Layering (or LLRGB). Color balancing and final touches were done in Photoshop. SGBNR (PixInsight LE) was used to smooth background noise on the luminance channel. Resized to approximately 800x600.

This image was an unguided exposure. This is one of the four Messier open clusters in Sagittarius (along with M18, M23, and M25 - excluding M24 as a Star Cloud).  Horizontal FOV is about 30'.


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

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