By Wilfried Schroeder
This paper deals with visual auroral data from Central Europe (530-480N) during the years 1545-1725. The reality of these observations has been discussed in detail. From the observations it can be demonstrated that the 11-year cycle in solar and auroral activity exists during this period. Tables give a compilation of aurorars per year, they show that in almost every year - before and druing the Maunder Minimum - auroras have been observed in Middle Europe. Because they are indicators of solar-geomagnetic activity it follows that no unusual variability in solar or geomagnetic activity is indicated.
Journal Geomagnetism and Geoelectricity 44 (1992), p. 119-128