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What should we expect for sensitivity? RMS width of PSF is around 4 pixels, and FWHM=2.35*RMS ~ 9.5 pixels. Fluxes are around 100K. Assume (guess!) around 1e per ADU so that corresponds to 100K electrons. Signal to Noise ratio is square root of that, or ~300
Sigma of centroid should be FWHM/SNR = 9/300 ~ 0.03 pixels. Cool.
I made trimmed source catalogs that retained the brightest 7 compact sources in each image.
We then need to do source association in (x,y) space. I cheated a bit and did this in 1 dimension, using ordering in y. This suggests we arrange the sources and their orientation on the detector to not have overlap in either x or y, to ease source association.
Computed mean position for each spot, then computed magnitude of difference of (postiion-mean) for each spot pair, and plotted that vs. separation. Looks interesting. The different frames have different amounts of turbulence:
Motion of center-of-spots: 
Magnitude of differential motion vs. separation between pairs, for all 4 images:
Looks like fitting differential motion vs. sqrt(separation) might work. Did those fits, here are the results:
Fit to
differential motion = a + b * sqrt(separation)
| frame | b | a |
|---|---|---|
| 42 | 0.1150 | 0.0579 |
| 50 | 0.1139 | -0.0306 |
| 58 | 0.0654 | -0.0189 |
| 81 | 0.0309 | 0.0345 |