A nice set of images
haven't seen any nightscapes with the EM1 before, What lens were you using? The stars look very sharp. My favourite nightscape lens when shooting with the GX-1 is the 20mm 1.7, the 14mm 2.8 is great but just a bit slow.
What ISO were these images taken at? The noise looks pretty good, I assume you had dark frame subtraction on?
Cheers
Jo