Fig. 2.— Top panel: Kepler transit lightcurve of Kepler-17b phase-folded, normalized and binned by 30 seconds. The best-fit model of this lightcurve is overplotted in red. The residuals from the best-fit transit lightcurve are plotted in the bottom panel. Occulted stellar spots produce a symmetrical pattern in phase in the residuals (see Section 7.2.1 of publication).