Transit sequence of the transit radius variation (TRV, left), autocorrelation function of the TRV transit sequence (center), and periodogram of the autocorrelation (right) for various planet–moon configurations around an m_V = 8 star asobserved with PLATO (see Sect. 3.3). Blue lines refer to an ɛ Eridani-like star, orange lines to a sun-like star. Subscripts “J”, “S”, “N”, “⊕”, and “☾ ” for the radii and masses refer to Jupiter, Saturn, Neptune, Earth, and the Moon, respectively. In the Jupiter–Neptune and Saturn/Super–Earth cases the TRV signal is clearly visible in the measured TRV time series. Consequently the signal is also visible in the autocorrelation. Due to only calculating the AC up toa time lag of have the observation length, a peak in the periodograms is only visible in the P_b = 30 d cases and not the P_b = 60 d cases. In the Neptune–Earth cases the signal in the TRV time series is barely visible, while the autocorrelation and periodogramfor the P_b = 30 d cases show a clear signal. There is no visible signal in any of the Earth–Moon cases for in the corresponding time series, autocorrelation, and periodogram.