thanks for the encouragement and great suggestions folks - all very much appreciated.
I have another clear night tonight, so i'm collecting some more data on this project to give a 4x4 grid each with 5 x 4min subs. I think the stitching program in its effort to reduce gradients is removing some of the milky way data at frame edges, so i'll look to try to fix that. Will also have a go at stretching and colour balance correction to ensure uniformity and to remove any undesired colour casts
before the stitching is done as suggested.
