Is there an easy way to find what subs are rotated?

What do you mean with "strange"? And are you referring to rotation you see in the end-result or with just those separate frames at the start?

@vincent-mod Sorry for the confusion, by strange rotation I mean most of the subs are aligned the same way, but there are a few outliers that are rotated at like 30 degrees or so. It's not a huge deal, but it does cause some lines to form around the edges of the image. You can see what I mean in this image.

I can see faintly, but it looks like all stars are aligned, so that means those frames were actually having a rotation in them from the start, APP aligns them to match the rest. If you add MBB and LNC in tab 6, those lines will likely disappear.

@vincent-mod Right, the images were taking at a slightly different angle APP did what it's supposed to do and aligned them well. I was just wondering if there is a simple way to see what images need to be rotated more than a few degrees and remove them from integration? 

I will give your suggestion a try though, it sounds like it might not even be an issue, if APP can make them go away. As always, thanks for your help.

There is no need to remove those frames, that would be a waste of data. You can always use MBB and LNC and thing like light pollution correction to get the slight lines removed. And you're most welcome! 🙂

@vincent-mod - searched for and found this thread. You suggestion worked perfectly for me, thank you for posting it. In my case, I had nudged my camera and didn't check any images coming out of it as the earlier ones were fine. Lesson learned. 🙂

For anyone else reading this, I used 1st degree LNC with 3 iterations. I also used advanced mode for normalization.