Upper panel: mean of continuum points μ_c minus mean of in-transit points μ_t over orbital phase (see Sect. 2.2 for details). The horizontal (green) area marks the range between the 16% and 84% quantiles of the distribution of points, the gray dashed line indicates the 99.9% quantile. The position of the secondary transit of HAT-P-11 b predicted by RV measurements is given by the vertical (magenta) line; the shaded area indicates the ± σ uncertainty of the prediction. Lower panel: estimate of the significance of the measurements in the upper panel using an F-test (see Sect. 2.2 for details).