GTC/OSIRIS HAT-P-11b white light transit curve for the night of August 30, 2016. Top panel: measured flux vs. time of HAT-P-11 and the reference star; the flux of the reference was multiplied by a factor of 14 for visualization purposes. Bottom panel: blue points represent the observed time series, the gray dashed line shows the best-fit model (transit model plus systematics and red noise) determined using our MCMC analysis, the black open circles show the light curve after removing the systematic effects and red noise component, while the red line is the best-fitting transit model. All the curves are shown with an arbitrary offset in y-axis.