the power of statistics

I pushed my faint-source proper motion measurement experiments to the signal-to-noise limits. Indeed, the system breaks down not when the signal-to-noise per epoch is low, but when the combined signal-to-noise in the data from all epochs is low. It works all the way down to a signal-to-noise around 4 in the combined data set, even when the per-image signal-to-noise is much less than 1.