Mario, this is rather perfect timing as I posted something a few days ago asking about reflections with my new RC8. I also imaged the Horse Head. See
here. I was imaging with a dslr and also got the airy disks around/near Alnitak. They aren't as strong as yours because your contrast is much more than my image. It was suggested that it might have been from the LPS filter.
I have collected more data from when I took that image and am now up to 30x5mins. I started processing the image last night.