Sunspot positions, areas, and group tilt angles for 1611−1631 from observations by Christoph Scheiner

Abstract

Aims. Digital images of the observations printed in the books "Rosa Ursina sive solis" and "Prodromus pro sole mobili" by Christoph Scheiner as well as the drawings from Scheiner's letters to Marcus Welser are analysed in order to obtain information on positions and sizes of sunspots that appeared before the Maunder minimum. Methods. In most cases, the given orientation of the ecliptic is used to set up the heliographic coordinate system for the drawings. Positions and sizes are measured manually on the screen. Very early drawings have no indication of their orientation. A rotational matching using common spots of adjacent days is used in some cases, while in other cases, the assumption of images being aligned with a zenith-horizon coordinate system appeared to be the most probable. Results. In total, 8167 sunspots were measured. A distribution of sunspot latitudes versus time (butterfly diagram) is obtained for Scheiner's observations. The observations of 1611 are very inaccurate, the drawings of 1612 have at least an indication of their orientation, while the remaining part of the spot positions from 1618-1631 have good to very good accuracy. We also computed 697 tilt angles of apparently bipolar sunspot groups observed in the period 1618-1631. We find that the average tilt angle of nearly 4 degrees is not significantly different from 20th-century values.

Solar Cycle Variability Induced by Tilt Angle Scatter in a Babcock–Leighton Solar Dynamo Model

“…Moreover, the tilt variation that we have implemented in above simulations, is extracted from the variation within a solar cycle data (for example, cycle 23 in the analysis of Stenflo & Kosovichev (2012) and cycle 21 in the analysis of Lemerle et al (2015)). In observations (e.g., Dasi-Espuig et al 2010;Wang et al 2015;Arlt et al 2016), we find the tilt to have cycle-to-cycle variation in addition to variations within a cycle. Motivated by these observational results, we double the tilt fluctuations, i.e., we now take σ δ = 30…”

Records of sunspots and aurora candidates in the Chinese official histories of the Yuán and Míng dynasties during 1261–1644

“…As MS has some records of sunspots dated after 1611 (MS#S21−S26), we tried a brief comparison between these datasets. We surveyed sunspot drawings in relevant periods within publications by early modern astronomers as we surveyed the published contemporary sunspot drawings by Scheiner (1630), Malapert (1633), and Gassendi (1658), which are conveniently reviewed by Zolotova & Ponyavin (2015) and Arlt et al (2016). We found a probable coincidence between Chinese sunspot records and Western sunspot drawings in 1618.06/07, i.e.…”

Iwahashi Zenbei’s Sunspot Drawings in 1793 in Japan

“…Recently, several authors revisited sunspot number (S N ) in general to make crucial contributions (Clette et al, 2014;Svalgaard and Schatten, 2016;Vaquero et al, 2016) based on the latest discussions on raw sunspot data within early modern scientific documents, consisting of sunspot number counting and sunspot drawings (e.g. Vaquero, 2007;Vaquero and Vázquez, 2009;Arlt, 2008Arlt, , 2011Diercke et al, 2014;Usoskin et al, 2015;Arlt et al, 2016;Carrasco and Vaquero, 2016). Within these datasets, sunspot drawings are of greater value as they provide information not only on S N but also on sunspot area, distribution, locations, and so forth (Vaquero, 2007;Vaquero and Vázquez, 2009).…”