Top: sliding FT (sFT) of HS 2324 in the region between 449 and 498 μHz. The color-coded amplitude is given in σ units, i.e., amplitude divided by the mean noise of each FT. Because each FT is computed in a short subrun of 9.3 days, the FT mean noise is high and the color-coded S/N appears much lower than in Table 4. Bottom: sliding WF (sWF) obtained using a single sinusoid of constant frequency and constant amplitude of one, without any noise. The frequency scale is the same in both panels. See text for more details on sFT and sWF computations.