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Earth, Planets and Space
Fig. 2 | Earth, Planets and Space

Fig. 2

From: Records of sunspot and aurora during CE 960–1279 in the Chinese chronicle of the Sòng dynasty

Fig. 2

Change of the number over years for all and naked-eye sunspots: The number of naked-eye sunspots and the sunspot numbers are plotted with solid line and dashed line, respectively. The sunspot region data used for naked-eye sunspot calculation are retrieved from the NASA database (http://solarscience.msfc.nasa.gov/greenwch.shtml), which are originally given by the Royal Greenwich Observatory (RGO), US Air Force (USAF), and the US National Oceanic and Atmospheric Administration (NOAA). The yearly mean sunspot number is retrieved from WDC-SILSO, Royal Observatory of Belgium, Brussels (http://www.sidc.be/silso/datafiles)

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