A lot of images were trailed due to vibration, wind and drifting. I had about 4 good frames to use for stacking. A couple of these were around a minute and didn't show much, so I ended up using just two frames of 115 and 120 Seconds at ISO 1600.
This is the first frame straight off the camera
Frames 1 and 2 had a Dark Frame
(an exposure of similar duration with the lens cap on to capture just camera noise) subtracted using Photoshop, and were stacked together. Stacking reduces noise by increasing Signal to Noise Ratio.
Finally the image was adjusted for colour, brightness and contrast in Photoshop and passed through 'Neat Image' to reduce noise. The image was not adjusted to look 'red'. The red colour came out when brightness and contrast were greatly boosted.
Update from 2009
This horsehead image is much closer to the exposure times required and is a stack of 7 frames
taken at 2 minutes each with an Antares 8" Newtonian on equatorial mount.
The HorseHead still proves elusive
this is 12 frames that were highly
washed out by street lighting.
In suppressing the unwanted light,
the image is also suppressed.
But The Horse can't hide for ever,
I'm closing in ....