I have an interesting question for those who know something about star alignment when you're stacking imaging. I've got an 11 inch Edge and a QHY 10 CCD camera. As an example, I stacked 100 x 2 minute subs. The Star align function worked fine in Pix Insight, but having successfully run, the images are not aligned. When I stack them manually, something curious happens - if I align them all on a star in the centre of the image, then the overlapping stars going out from the centre form arcs..... so that the further from the centre, the bigger the arc that the stacked stars make. If I align the images manually using a star at a corner of the image as an alignment point, the stars heading away from that corner form arcs, radiating larger the further from the star they go.
It's almost as if the stacked images are slightly rotated, with rotation increasing in line with the number of subs. I'm to work out why. Any ideas would be gratefully received.....