statistic as a function of V mean magnitude for the VR combined light curves. The RR Lyrae stars V1 and V2 are labelled, as are the new SX Phe stars V6 and V7 and the one candidate SX Phe star. The cyan points correspond to the blue stragglers identified by Cote et al. (1991). The long-period variables V4 and V5 do not appear on this plot because they are saturated in the R filter. The solid blue curve is the median (50%) curve determined from our simulations and adjusted to fit the real data above V ~ 19 mag. The dashed red curve represents our variable-star detection threshold in set using our simulations to limit our false-alarm rate to ~0.1%. The solid red curve represents our adopted variable star detection threshold when we take into account the systematic errors. We additionally limited our variable-star search to stars brighter than V = 20.6 mag (vertical dashed red line).