Monthly Sunspot Data, from 1749 to “Present”
Monthly numbers of sunspots, as from the World Data Center, aka SIDC. This is the version of the data that may occasionally be updated when new counts become available.
Month of the observation.
Number of sunspots.
WDC-SILSO, Solar Influences Data Analysis Center (SIDC), Royal Observatory of Belgium, Av. Circulaire, 3, B-1180 BRUSSELS. Currently at http://www.sidc.be/silso/datafiles.
t = octave.dataset.sunspot_month;