Thanks everyone!
A great reminder about the potential of modest cameras.
Yes isnt it. The camera is on loan to me from Canon to see just what it is capable of. Its far from as easy to get this kind of result with it, and the gigapan head helped a lot. This really was an experiment to see how it works before taking it on the road to somewhere 'nice'.
Has made me put a bit of thought into what could be the best astro/night shooting setup.
The Gigapan epic pro is rather large and bulky , a smaller camera with a good fast lens and a smaller gigapan would possibly work well.