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Contains:  NGC 5195, Whirlpool galaxy, M 51, NGC 5194
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Messier 51, 





    
        

            Daniel.P
Messier 51

Messier 51

Technical card

Resolution: 2448x1872

Dates:May 25, 2017

Frames: 13x900" -12C bin 1x1

Integration: 3.2 hours

Darks: ~7

Flats: ~5

Bias: ~20

Avg. Moon age: 29.15 days

Avg. Moon phase: 0.17%

Mean SQM: 21.40

Astrometry.net job: 1610964

RA center: 202.475 degrees

DEC center: 47.206 degrees

Pixel scale: 0.699 arcsec/pixel

Orientation: 97.483 degrees

Field radius: 0.299 degrees

Locations: Duc, Prayssas, Lot et Garonne, France

Data source: Backyard

Description

I tested on this photo a "special" treatment I had in mind for some time.
My first 7 exposures where reasonably sharp, but during this night the conditions deteriorated
as the galaxy moved away from the zenith and the 6 remaining exposures had bad FWHM (up to 4 arcsec).
I used a mask to image the galaxy and high SNR areas using the 7 sharp exposures and image the rest of the picture with the full set of 13 exposures to limit the noise in low SNR.

This is the result ... the extensions of the galaxy show less noise using all the exposures, without making the galaxy less sharp.

Pre-processing done in Pixinsight :
- overscan area offset correction
- bias correction
- hot pixel correction
- debayer
- registration
- stack
Processing done in Pixinsight :
- backgroung color neutralisation
- color calibration using galaxy
- sky background removal (DBE in PI)
- slight deconvolution (masked)
- non linear image creation
- green neutral
- color saturation boost masked and background desaturation
Final image :
- jpeg calibration done in Mac Photo (levels adjust and further saturation boost and color balance)

Comments

Author

Daniel.P
Daniel.P
License: None (All rights reserved)
1533
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Messier 51, 





    
        

            Daniel.P