The last image was stacked with Deepskystacker which is lousy at handling rotation with any distortion.
Here is a version of the same data stacked with RegiStar 16MB
http://d1355990.i49.quadrahosting.co.../RGST_vers.jpg
It is upsized by a factor of 1.6. It shows the real star profiles in the corners.
Never mind the nuances of nebular detail just pixel peep at the corners.
I am happier than the pig Mike's fevered ancient brain can see in random spatterings of dust and gas.
The lodestar guider just arrived.
Bert