[Stephane]

Hey folks,

I am trouble shooting a large circular artefact with my newly acquired rig. The artefact is not entirely removed with flats. Its center appears to be the same as the center of my optical train, although this could be coincidental. My setup is with a colour zwo2600mc process GPU coma corrector, and an OAG. The focuser is the Esatto. My focal length is 800mm. No filter.

Image1: Uncalibrated sub
Image2: Calibrated sub
Image3: Starless integration of 4 calibrated subs insanely stretched.

Images have had background subracted in order for the artefact to become visible.

Any help or trouble shooting suggestions would be much appreciated.

Regards,
Stephane