Reconstructed solar activity around the Spörer minimum. Panel A: the black curve with grey-shaded error bars represents the main reconstruction and is identical to that in Fig. 12, while the red curve depicts a reconstruction based on one realisation of the simulated noise series (see text). Panel B: FFT spectrum (amplitude) of the main SN reconstruction (shown in panel A) for the period 1400–1550, while the red dotted line depicts the upper 95th percentile of the FFT spectra of 1000 noise-based reconstructions for the same period (see text). Panel C: same as panel B, but for OSF.