Awsome shots Bird, makes me really want to learn how you do it.
I have tried with a few pics in registax, registar and iris, but have failed each time and given up, not having my mount tracking yet or polar aligned doesn't help me any either.
I will have to dedicate some time in reading how and what is the best way to use these programs, your pics definately inspire us newbies to want to achieve similar results.
Thanks.