Averaged periodograms computed with Eq. (1) using all one-day subseries available during a minimum (2008, solid dashed lines) and a maximum (2003, solid solid lines) of the solar cycle. Each color indicates the observation of one SPM channel. Differences with the solar cycle are observed at frequencies ν < f_l (i.e., at periods >6.2 h). The peak at ν = 5570 μHz affecting the PSD of the blue and green SPM data is an electronic artifact related to the calibration period used by the acquisition system of VIRGO. The gray shaded area indicates the frequency range corresponding to the typical duration of planetary transit (from ~ 25 min to several hours).