Sunspot numbers during 1736–1739 revisited Original Research Article

Some periods in the sunspot number reconstruction composed by Hoyt and Schatten [Hoyt, D.V., Schatten, K.H. Group Sunspot Numbers: a new solar activity reconstruction. Sol. Phys. 179, 189–219, 1998. Reprinted with figures in Sol. Phys. 181, 491–512, 1998], are based on very few records. For example, there are only a few solar observations during the years 1736–1739. In this paper we intend to improve the reliability of the sunspot numbers reconstruction developed by Hoyt and Schatten for this 4-years period based on information about solar activity published in three journals of that epoch: “Philosophical Transactions”, “Histoire de l’Académie Royale des Sciences”, and “Nova Acta Eruditorum”. We were able to identify 42 papers with solar observations, including 30 with relevant information on sunspots. Based upon this new outlook, a reconstruction of the monthly solar activity for these years is proposed.