TY - JOUR

T1 - Solar Activity Level in 1611–1613: Sunspot Groups and Areas

AU - Zolotova, N. V.

AU - Vokhmyanin, M. V.

PY - 2021

Y1 - 2021

N2 - Early telescopic sunspot observations provide unique information extending our knowledge onsolar activity back to the seventeenth century. In our work, we analyse sunspot parameters reconstructed fromobservations in the 1610s. Comparing distributions of historical and modern sunspot group areas, the fraction ofsmall sunspots apparently missing in historic drawings was estimated. We suggest that reports might lack from 20to 85% of sunspot groups depending on the style of observations. The number of sunspot groups corrected for thefraction of lost spots indicates that the period of 1612–1613 apparently belongs to a cycle of a secular maximum.

AB - Early telescopic sunspot observations provide unique information extending our knowledge onsolar activity back to the seventeenth century. In our work, we analyse sunspot parameters reconstructed fromobservations in the 1610s. Comparing distributions of historical and modern sunspot group areas, the fraction ofsmall sunspots apparently missing in historic drawings was estimated. We suggest that reports might lack from 20to 85% of sunspot groups depending on the style of observations. The number of sunspot groups corrected for thefraction of lost spots indicates that the period of 1612–1613 apparently belongs to a cycle of a secular maximum.

M3 - Article

VL - 61

SP - 1001

EP - 1008

JO - Geomagnetism and Aeronomy

JF - Geomagnetism and Aeronomy

SN - 0016-7932

IS - 7

ER -