Strange patterns in star images

[RSM]

Good Evening. Been a while since I've posted. All the cloudy nights have meant I've not had a great deal of new data to work with so had to resort to playing around with some older files, trying to tweak things. That was until earlier this week when the skies cleared and with no moon, I managed to get some images shot of the Flame and Horsehead Nebulae, M45 and also the Whirlpool Galaxy. Just been processing the Nebulae in Pixinsight (trial period over, proper money paid!) and have managed to get the image below from 20 x 60 second subs.

I think I need to spend a bit more time on extracting the background with the DBE function. I lazily used the Automatic Background Extractor and I think there is some light pollution towards the bottom left I could work on a bit better. That said, I'm quite pleased with this. One question I have is that in the brightest star images, there are strange patterns in the star glow. Looks like they could be related to something blocking the light passage in my scope, possibly the primary mirror holders??? I wonder if there is any way I can avoid having them in the images?

Any thoughts would be gratefully received.

Thanks once again for looking.

Richard.

[bishbosh]

Lovely! I wish I could get something half as good as that. The spikes or whatever they are called look quite long, was that how it came out or were they post-processed?

[RSM]

Lovely! I wish I could get something half as good as that. The spikes or whatever they are called look quite long, was that how it came out or were they post-processed?

Hi. The stars are as they come. I generally work on getting rid of the background noise and bringing out the detail in dust clouds and nebulosity.