Periodograms of the daily number of dust impacts with morphological types A and B during six years in the focusing phase (2007–2012, blue curve, top panel) and six years in the defocusing phase (September 2017 to August 2023, red curve, bottom panel). The two panels are scaled identically; the estimated 95% significance thresholds are indicated by grey shaded areas. Frequencies of interest are marked by vertical lines as in Fig. 9.