The sunspot numbers during 1736-1739 revisited

Vaquero J.M., Gallego M.C.,Trigo R.M.
Advances Space Research, 40, 1895-1903, DOI: 10.1016/j.asr.2007.02.097

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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'Acade´mie 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.