M31 (Mosaic)

My first attempt at a mosaic image.  I choose M31 since it required only 4 panels to achieve a reasonable framing.  After calibration and stacking in CCDstack, I decided to combine the mosaic panels using a combination of RegiStar and PS. After a little experimentation I was able to achieve an invisible join between the panels. This was also my first application of Pixinsight's DBE, Background Neutralization and Colour Calibration functions on an image.  I was particularly impressed by the DBE function which gives superior results than the PS equivalent. 

The image is a H alpha red blend LRGB image and for those that might be interested, consists of the following sub frames for each of the four panels:

The LRGB subs are 600s and the H 1800s.

The H was blended with the red channel using the PS screen function after black clipping the H image.  

I think this might be my last mosaic for a little while since it took about 5 weeks from start to finish,  mainly due to the UK weather and the fact that I wanted quite a long exposure per panel (c 13 hours) in order to capture faint detail. I took it as a good sign that you can see the faint dust clouds in the companion galaxy (M110) reasonably clearly.