English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Christoph Scheiner was one of the most outstanding astronomers in the historyof the sunspot observations. His book, Rosa Ursina, is the reference workregarding the study of the earliest sunspot records. The sunspot observationscompiled by Scheiner in Rosa Ursina and Prodomus, including records made byother observers, forms one of the main references of the observations known forthat period; particularly around the 1620s. Thus, his work is crucial todetermine the solar activity level of the first solar cycles of the telescopicera. The number of sunspot groups recorded in Scheiner's documentary sourceshas been included in the existing sunspot group number databases. However, wehave detected significant errors in the number of groups currently assigned toScheiner's records. In this work, we reanalyze the information in Scheiner'ssource documents. Consequently, the standard 11-yr solar cycle shape for thesecond solar cycle of the telescopic era, which is not clear in previousstudies, now becomes evident. In addition, the highest daily number of groupsrecorded during this cycle (8 groups) is 20% less than the one included in theexisting sunspot group number databases. Using the hypergeometrical probabilitydistribution, we find that solar minima in 2008-2009 and 2018-2019 arecomparable to the most probable solar activity level of the minimum around1632. In particular, the estimated lower limit for the solar activity in 1632is even comparable with the solar activity level in 2008 and 2018.

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