One chance. Once chance to get it right, with sooo many things that could go wrong!
Almost ten years ago I could use for a night a telescope on an equatorial mount to piggyback my Canon T70 with a 200mm f/4 lens and ISO 400 film :D
One of the targets was of course M31, the Andromeda Galaxy. It was a lot of fun, as one could not see what he's doing and manually guiding 30 minutes it's not an easy task: the slightest mistake could and would of ruined the picture.
But I kept my hand steady, my eye sharp and prayed to the control towers to divert planes from my field of view:
Take a good look at it as we're going to crash with this giant galaxy in no time (~4 billion years!).