Top left: O−C diagram following the Pál et al. (2011) linear ephemeris. The new points from TASTE (Table 2) are plotted in blue filled circles. Bottom left: O−C diagram following a linear ephemeris, fitted ignoring the two data points (red squares) from Szabó et al. (2010). Top right: same as top left, zoomed on the transits collected in Jan.-Feb. 2011. Bottom right: the O−C diagram folded over an ephemeris with  ⟨ P ⟩  = 2.91625 days, perturbed by a sinusoidal TTV with a period of P_TTV = 1150 days and an amplitude Δ_TTV = 0.005 days.