Thanks Mike, Jase, Petra and Frank for the comments,......
Mike, the slightly darker circles around the brighter stars are left after removing CA with Noels actions to remove small blue/violet halos..(thats why I got them).I shall invest in a lumicon anti-fringing filter to fix this, but they do a pretty good job of removing them.
Didn`t use any noise reduction at all. As for the color gradients, the original 16bit tiff image doesn`t look quiet as obvious as the jpg but I know what you mean, don`t know why yet as I only used whats in PS and a action or two? shall work on that??
Thanks for the comments as it all helps me with my processing and I have come a long way over the year!!!!
Cheers Gary