To achieve this photo I used the following:
No tripod (I just sat the camera on the ledge)
16 shots in raw plus one dark frame (turned off slow frame NR, then turned it back off tor the dark frame)
f6.3 (Pentax DA16-45)
Cable Release (I found interval timer inbuilt didn't work properly for some strange reason, I think because of the buffer limits)
Lightroom (to process the raws)
Star Trails (this app really suprised me, its amazing)
Vertus fluid mask
Believe it or not I used absolutely no noise reduction software.
Clever stuff on the astronomy for beginners group.