Hi! Thank you very much for your comments!
Unfortunately, the circular structure to the right side of the comet head is a reflection of the comet on the filter. I'm working on a new version without that artifact, I have been able to remove it very well. I'll upload the new version in two weeks (I'm going on a trip for 10 days) and a brief explanation of how I did this.
Apparently, the APOD guys didn't find interesting my image...
I like the image by Gerald. But things go a lot easier when you don't have to manage with the dynamic range of the object...
Best regards,
Vicent.