Comparison of the periods derived from the S_IRT-indices time series vs. the periods derived from the S_MWO time series (in the upper panels) with the identity as solid line. The lower panels show the relative difference (in percent) between the periods derived in the S_IRT-indices and S_MWO time series vs. the period obtained from the S_MWO time series with a 3σ error for the period ratios. The periods with a FAP less than 4.55 × 10^-2 (2σ) are labelled with a plus symbol and periods with a FAP greater than 4.55 × 10^-2 with an asterisk.