Open Access
Research Article

Figure 4.

image

Download original image

Top curve. The ratio of annual RGO group counts to the yearly average of group counts of all observers (with RGO omitted; AllUNSC(−RGO)) from 1874 to 1920. Middle curve. The ratio of annual Wolfer group counts to the yearly average of group counts of all observers (with Wolfer omitted; AllUNSC(−Wolfer)) from 1876 to 1920. Note the offset of the left and right y-axis scales. Bottom curve. Annual sunspot number (SN*), 1874–1920. Dashed-line linear fits are given for the two top traces. The Vaquero et al. (2016) database (http://www.sidc.be/silso/groupnumberv3) was used for this analysis (with Mt. Wilson (Center of Disk) eliminated).

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.