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Friday, September 17, 2010

NGC 7000, the "North America" nebula closeup, second round

Close up of the NGC 7000, the "North America" nebula.
Image is composed from O-III and H-a narrowband channels to a bi-color image.
This palette is close to a visiblel spectrum.
I'll shoot more O-III and S-II for this, to build a HST-palette image, later.

I managed to solve the orthogonality problem between the optical path and the CCD. Now stars are as good as they can in my imaging system. I have reduced Meade LX200 GPS 12" f10 to f5 by misusing a Celestron f6.3 reducer by placing it at longer distance from CCD and hence grove the reduction factor.
The price is coma at both ends of the image but I can live with it. This system gives me about 30* field and a spatial resolution of 0,75 arc seconds/pixel. 

An experimental starless image. Stars are removed in one processing step and placed back with zero data lost. Sometimes I publish an image with a reduced stars to show the actual nebula better. It looks kind of nice, or spooky, that's a matter of taste.


Processing work flow: 
Image acquisition, MaxiDL v5.07. 
Stacked and calibrated in CCDStack. 
Deconvolution with a CCDSharp, 30 iterations. 
Levels, curves and color combine in PS CS3.

Telescope, Meade LX200 GPS 12" @ f5 
Camera, QHY9 Guiding, SXV-AO @ 6Hz 
Image Scale, 0,75 arcseconds/pixel 
Exposures H-alpha 15x1200s, binned 1x1=5h
O-III 1x1200s binned 3x3

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