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M31  - The Great Andromeda Galaxy
(click and scroll on the image for increasing resolution)




Object:            M31, barred spiral galaxy in Andromeda. 8 tiles mosaic.
Telescope:    
Astrograph 250 f/4 Newton .  Paramount ME.  Atik 16200 ccd.  Filters: Chroma LRGB & Baader Halpha.
                      Background gradient correction: Samyang 135 @ f/2.7.  Artemis 4021 ccd.  Filters: Baader LRGB.
Exposures:        L :  60 x 15'   (15:00 ) 
(each tile)          R:  30 x   5'   (  2:30 ) 
                          G:  30 x   5'   (  2:30 )  
                          B:  30 x   5'   (  2:30 )
                         Ha:  18 x 20'   (  6:00 )
                       Total (eight tiles):    228 hours
Resolution:       1.7"/pixel (downsampled from 1.28"/px).  
Date:                August 2022 - December  2023
Site:                 
La Sagra Observatory  Puebla de Don Fadrique (Spain)    - mag 7 professional observatory skies -  
Processing:
Bias, Dark & Flat calibration
Multiscale background gradient correction
Photometric Mosaic Script
SpectroPhotometric Color Calibration
BlurXTerminator
MLT linear noise reduction
GHS and Histogram stretching
Starnetv2 for star masks
HighDynamicRange Multiscale Transform
Local Histogram Equalization
Color saturation
and Curves adjustments


Software:
PixInSight