Wavelet transform (scalogram) of the r′ filter light curve, mapping the time-frequency evolution of the signal. Significant QPO amplitude is visible around ~2 s (delimitated by horizontal white lines) but variability is also present in the range ~100 s. High flaring activity is also visible around 1000 s in the second orbital cycle. The thin black line at the top of the figure delimits the cone of influence below which the information is fully usable.