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PSF stability

Some examples of PSF variation over the array together with radial and cumulative profiles of the PSF for each of the 32 detectors.   A Moffat profile with  beta = 2.5 provides a reasonable analytic approximation.  Note that the curved focal plane, and the flat detector geometry, yields astigmatic PSFs for images taken slightly above or below optimum focus (outside-in or inside-out depending on the sign)