Fig. 2.
Example of a typical sunspot drawing from the MWO dataset taken on 9 November 1917 between 8:35 and 9:00 (local time). Measured sunspot field strengths are shown in units of hundred G and their polarities designated as “R” and “V” (for red and violet, which corresponds to the positive and the negative polarities). Credit: Carnegie Observatories.
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