What causes difraction patterns in difference images?

Hi, I am just wondering what causes patterns like this in a difference image:


Does it have to do with a mismatch between the template and calexp PSF during PSF matching? Was either the template or calexp PSF model miscalculated?

These “ringing” artifacts are typically the result of effective deconvolution, typically when the science image has better seeing than the template in standard Alard & Lupton image differencing.

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