[rat156]

Hi All,

Other than the Jupiter shots I took a few nights ago I got some of NGC 6744, mainly to test out the field flatness etc.

Here's the results of 6 x 10 minutes exposures, stacked.

As can be seen there's a bit of a problem in the upper LHS of the frame.

There's a crop from the lower RHS and upper LHS as well so you can see the difference.

What is the most likely cause of this?

Cheers
Stuart