[Joshua Bunn (Joshua)]

Hi all,

Took some exposures with my setup last night, after going through the motions of the initial steps of PA, fitting PEC curve, collimation, then a large tpoint model.

The equipment for the purpose of diagnosis is PME, Planewave cdk 12.5, STL11000.

The exposures i have attached are single 5 min unguided images of m83 and ngc 4706 respectively, both unbinned. The quality has degraded a little due to compression.

Not focusing on tracking, if you look at the top left of the images, there is not soo much elongation but as you go to the bottom right, the stars become elongated. Could this be collimation error or image plain tilt?

Looking at the tilt in X and Y from ccdI, is this enough tilt to cause the issue you see in the exposures at bottom right? I would have thought the tilt measurements would have been much larger looking at the bottom right of the images.

I ran these and other exposures through ccdinspector and i have attached the results. My questions with this are, why would the binned 3x3 exposures exhibit far less field curviture than the unbined images?

Could it be a collimation issue that caused the elongated stars?

What is an exeptable collimation figure to aim for?

Its wierd, cause i get ideal collimation and curviture results when tunning the secondary screws using 30 sec exposures, then when i come to take an image, this happens.

any help appreciated.

thanks, Josh