Revisiting Christoph Scheiner's Sunspot Records: a New Perspective on Solar Activity of the Early Telescopic Era

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Main Authors: Carrasco, V. M. S., Muñoz-Jaramillo, A., Gallego, M. C., Vaquero, J. M.
Format: Preprint
Published: 2025
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author Carrasco, V. M. S.
Muñoz-Jaramillo, A.
Gallego, M. C.
Vaquero, J. M.
author_facet Carrasco, V. M. S.
Muñoz-Jaramillo, A.
Gallego, M. C.
Vaquero, J. M.
contents Christoph Scheiner was one of the most outstanding astronomers in the history of the sunspot observations. His book, Rosa Ursina, is the reference work regarding the study of the earliest sunspot records. The sunspot observations compiled by Scheiner in Rosa Ursina and Prodomus, including records made by other observers, forms one of the main references of the observations known for that period; particularly around the 1620s. Thus, his work is crucial to determine the solar activity level of the first solar cycles of the telescopic era. The number of sunspot groups recorded in Scheiner's documentary sources has been included in the existing sunspot group number databases. However, we have detected significant errors in the number of groups currently assigned to Scheiner's records. In this work, we reanalyze the information in Scheiner's source documents. Consequently, the standard 11-yr solar cycle shape for the second solar cycle of the telescopic era, which is not clear in previous studies, now becomes evident. In addition, the highest daily number of groups recorded during this cycle (8 groups) is 20% less than the one included in the existing sunspot group number databases. Using the hypergeometrical probability distribution, we find that solar minima in 2008-2009 and 2018-2019 are comparable to the most probable solar activity level of the minimum around 1632. In particular, the estimated lower limit for the solar activity in 1632 is even comparable with the solar activity level in 2008 and 2018.
format Preprint
id arxiv_https___arxiv_org_abs_2501_10903
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Revisiting Christoph Scheiner's Sunspot Records: a New Perspective on Solar Activity of the Early Telescopic Era
Carrasco, V. M. S.
Muñoz-Jaramillo, A.
Gallego, M. C.
Vaquero, J. M.
Solar and Stellar Astrophysics
Christoph Scheiner was one of the most outstanding astronomers in the history of the sunspot observations. His book, Rosa Ursina, is the reference work regarding the study of the earliest sunspot records. The sunspot observations compiled by Scheiner in Rosa Ursina and Prodomus, including records made by other observers, forms one of the main references of the observations known for that period; particularly around the 1620s. Thus, his work is crucial to determine the solar activity level of the first solar cycles of the telescopic era. The number of sunspot groups recorded in Scheiner's documentary sources has been included in the existing sunspot group number databases. However, we have detected significant errors in the number of groups currently assigned to Scheiner's records. In this work, we reanalyze the information in Scheiner's source documents. Consequently, the standard 11-yr solar cycle shape for the second solar cycle of the telescopic era, which is not clear in previous studies, now becomes evident. In addition, the highest daily number of groups recorded during this cycle (8 groups) is 20% less than the one included in the existing sunspot group number databases. Using the hypergeometrical probability distribution, we find that solar minima in 2008-2009 and 2018-2019 are comparable to the most probable solar activity level of the minimum around 1632. In particular, the estimated lower limit for the solar activity in 1632 is even comparable with the solar activity level in 2008 and 2018.
title Revisiting Christoph Scheiner's Sunspot Records: a New Perspective on Solar Activity of the Early Telescopic Era
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2501.10903