SNs (ISN_v2 normalisation) reconstructed here for 1–969 CE, split into two panels for clarity. The black curve, grey shading, and red curve depict the mean annual reconstructed SN, its 68% confidence interval, and the 22-year smoothed evolution (see main text), respectively. These data are identical to those in Fig. 1d. The digital version of these data is available at the CDS. The green curve depicts the smooth decadal SN values reconstructed from multi-proxy cosmogenic isotope data (Wu et al. 2018).