M51, Whirpool galaxy

This galaxy has been the very first try to take a decent astrophoto, because I had to try twice. In the first try there was the full Moon, and knowing that is not a good idea taking astrophoto when there's so much light, combined with city-lights (light pollution), I wanted to try in any way.

In fact the first try has been a complete failure:

As you can see there's a dark area above the galaxy, due to a moonlight reflection on the coma-corrector of my telescope. 

So I only needed to wait the right moment, I mean without the Moon. And so it was!

These ones are the work of two nights, where I take 40 lights frames, 20 dark frames and 60 flat frames, for a total of 2 hours of lights integration:

For comparison, I put both the black-white version and the colour version, got in two different elaboration sessions.

For both, I've used PixInsight, but for the colour version, I had to study how to achieve some result, like removing vignetting, colour gradient and clean the noise present everywhere.

For pilot my setup I've used the ASI Air, where I got an excellent result:

The graph-guide was really close to the central line, sign that the mount was working very well, apart from some moments when there was the wind.
Speaking about frames, for this picture I've taken 40 light frames, 20 dark frames and 60 flat frames, but no bias frames because using a CCD camera it doesn't need to take bias frame. I've tried to take them, but PixInsight couldn't extract any information, so it was unuseful.

Finally, it's been a good experience. I've learnt a lot of things, what to do and what to not do, but if I want to keep on taking pictures in town, I need a filter for the light pollution.

See you.