Final PDC (first panel) and SAP (third panel) time-series adjusted according to the steps of Sect. 3. The corresponding Lomb–Scargle periodograms are shown at the bottom. The dashed-dotted blue line marks the 99% confidence level. For SAP data, there is a significant peak to 46.6 days also found in Fig. 6. As can be seen, the PDC time-series has a flat periodogram for periods longer than 20 days confirming that the PDC pipeline tends to remove all the long-term trends.