Examples for high (upper panel) and low S/N (lower panel) detections. The amplitude spectra shown are the results of the DFT analysis of the TFA(FOUR) time series using the fundamental pulsation frequencies and their first 14 harmonics both in the TFA filtering and in the pre-whitening. The peaks come either from the BL side lobes or from the high-frequency components leaked through the Nyquist frequency at ~24.47 c/d.