A forgotten sunspot record during the Maunder Minimum (Jean Charles Gallet, 1677)

Abstract

ABSTRACT We have located a forgotten record of sunspot observations made by Jean Charles Gallet in the year 1677, in the middle of the Maunder Minimum (the period between 1645 and 1715 characterized by very low solar activity). Gallet observed one sunspot group from April 9 to 15 and another from October 1 to 6. While the group observed in April was also recorded by other astronomers of that time, no observer recorded the group observed by Gallet in 1677 October. Moreover, Gallet indicated the latter group was composed by four different spots and provided astrometric measurements of the main spot. We have calculated the latitudes corresponding to the main sunspot recorded in the October. The mean latitude is around 10º south. Therefore, this sunspot was observed in the southern hemisphere, as were most of the spots observed during the Maunder Minimum.