Paul, I think you are on the money. If you project my “spike” it pretty much aligns with Antares, skipping over around one and a half panels. Why that happens I have no idea! Interesting that you are experiencing a similar effect. How have you overcome this? I have tried moving my mosaic slightly and also rotating the camera but the spike just moves or rotates relatively. I checked out your post and your image looks amazing so far. I noticed you mentioned the southern winter - are you in Australia?
Leigh.