Sunspot numbers based on historic records in the 1610s - early telescopic observations by Simon Marius and others

Abstract

Hoyt & Schatten (1998) claim that Simon Marius would have observed the sun from 1617 Jun 7 to 1618 Dec 31 (Gregorian calendar) all days, except three short gaps in 1618, but would never have detected a sunspot -- based on a quotation from Marius in Wolf (1857), but misinterpreted by Hoyt & Schatten. Marius himself specified in early 1619 that "for one and a half year ... rather few or more often no spots could be detected ... which was never observed before" (Marius 1619). The generic statement by Marius can be interpreted such that the active day fraction was below 0.5 (but not zero) from fall 1617 to spring 1619 and that it was 1 before fall 1617 (since August 1611). Hoyt & Schatten cite Zinner (1952), who referred to Zinner (1942), where observing dates by Marius since 1611 are given, but which were not used by Hoyt & Schatten. We present all relevant texts from Marius where he clearly stated that he observed many spots in different form on and since 1611 Aug 3 (Julian) = Aug 13 (Greg.) (on the first day together with Ahasverus Schmidnerus), 14 spots on 1612 May 30 (Julian) = Jun 9 (Greg.), which is consistent with drawings by Galilei and Jungius for that day, the latter is shown here for the first time, at least one spot on 1611 Oct 3 and/or 11 (Julian), i.e. Oct 13 and/or 21 (Greg.), when he changed his sunspot observing technique, he also mentioned that he has drawn sunspots for 1611 Nov 17 (Julian) = Nov 27 (Greg.), in addition to those clearly datable detections, there is evidence in the texts for regular observations. ... Sunspots records by Malapert from 1618 to 1621 show that the last low-latitude spot was seen in Dec 1620, while the first high-latitude spots were noticed in June and Oct 1620, so that the Schwabe cycle turnover (minimum) took place around that time, ...

arXiv comment40 pages with 6 tables and 13 figures (paper in press), Astronomical Notes 2016

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Cited by in corpus (9)

• Visualization of the challenges and limitations of the long-term sunspot number record
• Sunspot positions, areas, and group tilt angles for 1611-1631 from observations by Christoph Scheiner
• Records of Sunspots and Aurora Candidates in the Chinese Official Histories of the Yuán and Míng Dynasties during 1261-1644
• Christian Horrebow's Sunspot Observations -- II. Construction of a Record of Sunspot Positions
• Revisiting Christoph Scheiner's Sunspot Records: a New Perspective on Solar Activity of the Early Telescopic Era
• Number of Sunspot Groups from the Galileo-Scheiner controversy revisited
• Sunspot observations by Charles Malapert during the period 1618-1626: a key dataset to understand solar activity before the Maunder minimum
• Revisiting the Amplitude of Solar Cycle 9: The Case of Sunspot Observations by W.C. Bond
• Accuracy of magnitudes in pre-telescopic star catalogues