Paul, thanks. I'll try leaving the NR on and see if that cures it.
Silv, yes there is some trailing visible on the originals. I'm not bothered about trying to salvage these photos, but more interested in the cause of the glow. The exif data on the images shows the wrong exposure time, I assume that CHDK doesn't overwrite the cameras settings.
It was awesome to see the aurora, and was a first for me. It certainly wasn't anything like in the photos though. Thankfully there was someone just around the corner from me on the Christchurch Port Hills on the night who knew what he was doing, I'll be keeping his shots as a memento
http://www.flickr.com/photos/redigua...in/photostream
http://www.youtube.com/watch?v=LnXlVeTfetw