[pmrid (Peter)]

I decided to run a new set of flats - high time since this is an entirely new scope combo - the only constant factor is the CCD. It's an Apogee Alta U8300 - a good camera without doubt.

But I'm seeing an odd artifact on the flats (and with plenty of pushing, it even comes out in stacked images) - it's a 5-point star-like shadow with somewhat curved and diffuse arms resembling a Japanese shuriken or something similar - occupying most of the image and centered in the middle.

These cameras have a mechanical shutter and it occurs to me that in short exposures, such as you do for flats and the like, there may be an artifact created by the opening (and closing I guess) of the shutter.
Anyone else experienced this?

Peter