I will repeat - great pictures!
I keep eyes on k-5iis and information about k-50. If i save money soon I think to buy one of them. I am sure they are very good cameras for astro pictures. And if i take one of them i will take the o-gps.
In the internet there are some pictures from k-5 and the gps with exposure 50-60 sec, and they are very beautiful.
But let me share some of my astro pictures. They are not stacked (the original single shots) and not very nice but i like them
The sky to the east from my garden:
The Moon Eye, az i call this picture:
Of course The MIlkyWay:
The Pleiades:
I have some other pictures but they were made with other cameras