Here's anoher spectrum from tonight. It's still got a bad S/N ratio but it is a little better than my last one. This was my first image for the evening. I then setup for a better exposure when I saw how this was... then computer problems struck.
After having to start the PC again, I had a series of captures running in CCDSoft when I got a virtual memory warning, and the thing slowed right down. I didn't think that when you pressed abort, CCDSoft would erase the images it had captured so far
... By then Eta was very low in the sky and the clouds started.
Oh well...
I have added the lines for H in green. This spectrum was catured at 8A/pixel.
I think I can see the potential of the ST8i now...
Al.