You're barred again!

Dave - well spotted! If you look even closer ( ) you'll see all the stars but the bright one are rugby balls. I'd normally scan each image and check FWHM and flatness then reject dodgy ones. It was a bit early in the morning to be doing that so I just stacked the lot!

I guess I was just interested in squeezing out the detail of the spiral arms and not really worried about rugby balls

Also, I've no idea how perpendicular the DSI chip is to the focal plane. My guess is that for 300 bucks, its not going to be perfect. Also, I'd be suspicious about the engineering quality of the C8.

There's a utility out there - the name escapes me - which will categorise both the optics and the CCD alignment of your system. I think its in the CCDWare suite of programmes. Its very tasty. But I wouldn't bother with the DSI. Now, when the next imager arrives, that's a different story

Cheers and appreciate the feedback, especially for spotting the errors and being very diplomatic about it

Go get that Atik working you slacker!

Dave