Have recently learned on separate occasions first about the script 'AberrationSpotter' and then about DynamicPSF (Thanks RBA!)
Together these tools make troubleshooting image train and focus issues an easier process. I used to move around on frames and look at the 4 corners in the zoom window and guess at a characterization of the stars there and then of course in the center. Now with AberrationSpotter a well thought out display in a compact screen size shows all 4 corners and the center auto-streched to nice levels. Then throw in DynamicPSF and you easily can tabulate quantitative numbers on stars of your choice. I very much like the way FWHMx and FWHMy are relative to the elongation and the angle of the major axis elongation is given by theta. Well done everyone.
Something that is lacking is some sort of quantitative number or numbers that show widening of one side of an elongated star (typically farther from the center). This sort of number I would call 'flare' and is generally seen in coma issues due to the optics I believe. Fortunately I don't have that in current equipment but that asymmetric characteristic is a missing quantitative number from the current tool best I can see. Fortunately DynamicPSF is extensible so it is not locked out for some future time.
So thanks to everyone involved,
Mark Johnston
