Temporal evolution of the chromospheric activity index . The primary rise and peak phases (dashed, vertical lines), the adopted pre-flare level (horizontal dashed line), and the best fit of the gradual decay phase along with the secondary and tertiary flares are indicated. The center of the x axis (time = 0 days) corresponds to the middle of the transit (T₀ [HJD,UTC] = 2 456 109.26164). The shaded pink area indicates the duration of an exoplanetary transit, the 1σ error for the data points varies between 3−4%.