Fig. 3 --- A plot of the standard deviation measured for the light curves of the KPNO 0.9-m telescope data. As opposed to Fig. 2, where we present precision in single exposures, here we produce 4.5-hour averages (4.5 hours/night or typically 45 exposures/night). Effectively we produce light curves with five data points each, one per night. The gain in precision for these nightly-averaged light curves is consistent with that predicted for normal errors on each light curve datapoint; the precision at a given magnitude is increased by a factor of the square root of N, where N is the number of points averaged together.