Morning all!
Last Friday evening I set myself the task of imaging M4. I got the alignment to be what I thought was good and took some 30s exposures. I then tried some longer exposures - 1 minute seemed OK but 2 minutes showed definite trailing.
When I examined the 30s photos on my PC, I noted that, although the stars were nice and round, they had moved between exposures. However this movement was not always in the same direction. A few shots would show movement in one direction and then all of a sudden the next 4 or 5 would shoe movement at right angles to what I'd seen before.
I'm assuming that the movement I was seeing was in RA and then DEC or vice-versa, but haven't been able to track it down. Do I need to start PEC training or is there something else I need to investigate?
I know this is a bit of the old "how long is a piece of string" question but any ideas would be gratefully accepted.
As for my image of M4 - I would say it needs longer exposures as the core wasn't very visible in the 30s ones. I'm not posting it because I think it's a dud!
Cheers,
Mario
go back though you'll find something amiss 
