Construction of the best-fit model from the four best light curves of WASP-3b observed at IAC80 (on 2011 May 7, May 21, Jun. 26, Jul. 20). The ID# of each transit (N1, N2, N4, N5) matches the corresponding entry in Table 1. Small gray dots represent the data points with the original cadence, while blue circles are binned on 120 s intervals. The red line is the best-fit from JKTEBOP (Table 2). Left panel: individual light curves. Transits are offset in magnitude by a multiple of 0.02 for clarity. Middle panel: residuals from the best-fit model. The reported scatter is evaluated on the binned points as the 68.27th percentile from the median value. Right panel: stack of all four IAC80 light curves with the best-fit model superimposed. The derived parameters are quoted in Table 2.