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Note, though, that it can have a larger effect on the calculated longitudinal position if only one end of the xtal has FHE firing. This can happen near one end of a xtal, where because of the light taper, the optical signal at the near end is larger than at the far end.
Tests to perform on an AGN skim or hard pulsar skim
I suggest that we need at least two test measurements of the observed PSF. Those tests are designed to separate issue (1) from (2)+(3), i.e. the time-evolution from the algorithm issues. Because we do not have maps with the crosstalk removed, we don't yet have a test for the effect of (4).
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