not suggesting it's true. just leaving a comment so I can follow your thread.
the sweet spot of your focal path was not where the camera's sensor looked. hence, the stars within the cluster have more coma than they'd have if you'd captured them in the middle of your sensor/the focal point.
I reckon, for DSS the Omega centauri is very difficult if the stars are not absolutely accurate. the process takes an educated guess and averages what it finds. And then there's the noise signal to filter out... oiyoiyoi ... I think.
As I said, only leaving a comment to easily follow your thread.
