A Revised Collection of Sunspot Group Numbers

Abstract

We describe a revised collection of the number of sunspot groups from 1610 to the present. This new collection is based on the work of Hoyt and Schatten (Solar Phys. 179, 189, 1998). The main changes are the elimination of a considerable number of observations during the Maunder Minimum (hereafter, MM) and the inclusion of several long series of observations. Numerous minor changes are also described. Moreover, we have calculated the active-day percentage during the MM from this new collection as a reliable index of the solar activity. Thus, the level of solar activity obtained in this work is greater than the level obtained using the original Hoyt and Schatten data, although it remains compatible with a grand minimum of solar activity. The new collection is available in digital format.

arXiv comment27 pages, 6 figures, accepted for publication in Solar Physics

References in corpus (22)

• Revisiting the Sunspot Number
• The Maunder minimum (1645--1715) was indeed a Grand minimum: A reassessment of multiple datasets
• Historical Sunspot Observations: A Review
• A homogeneous database of sunspot areas covering more than 130 years
• Sunspot positions and sizes for 1825-1867 from the observations by Samuel Heinrich Schwabe
• A solar cycle lost in 1793--1800: Early sunspot observations resolve the old mystery
• Revisited sunspot data: A new scenario for the onset of the Maunder minimum
• The butterfly diagram in the 18th century
• Level and length of cyclic solar activity during the Maunder minimum as deduced from the active day statistics
• Secular variation of hemispheric phase differences in the solar cycle
• Redefining the limit dates for the Maunder Minimum
• Sunspots during the Maunder Minimum from Machina Coelestis by Hevelius
• Sunspot Numbers and Areas from the Madrid Astronomical Observatory (1876-1986)
• A Simple Method to Check the Reliability of Annual Sunspot Number in the Historical Period 1610-1847
• Revised Group Sunspot Number for 1640, 1652, and 1741
• Sunspot Observations during the Maunder Minimum from the Correspondence of John Flamsteed
• Reconstructing Past Solar Activity using Meridian Solar Observations: the Case of the Royal Observatory of the Spanish Navy (1833-1840)
• Sunspot Catalogue of the Valencia Observatory (1920-1928)
• Forty two years counting spots: solar observations by D. E. Hadden during 1890-1931 revisited
• The solar differential rotation in the 18th century
• Sunspot group tilt angle measurements from historical observations
• Newly found sunspot observations by Peter Becker from Rostock for 1708, 1709, and 1710

Cited by in corpus (59)

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• Re-calibration of the Sunspot Number: Status Report
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• Thaddäus Derfflinger's sunspot observations during 1802-1824: A primary reference to understand the Dalton Minimum
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• The Solar Corona during the Total Eclipse on 16 June 1806: Graphical Evidence of the Coronal Structure during the Dalton Minimum
• Revisiting Christoph Scheiner's Sunspot Records: a New Perspective on Solar Activity of the Early Telescopic Era
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• Daniel Mögling's sunspot observations in 1626 - 1629: A manuscript reference for the solar activity before the Maunder Minimum
• Stephan Prantner's Sunspot Observations during the Dalton Minimum
• Sunspot Observations by Hisako Koyama: 1945-1996
• Revisiting Kunitomo's Sunspot Drawings during 1835-1836 in Japan
• Soonspot: Software to Determine Areas and Sunspot Positions
• Sunspot Drawings by Japanese Official Astronomers in 1749-1750
• A modern reconstruction of Carrington's observations (1853-1861)
• Scale Transfer in 1849 : Heinrich Schwabe to Rudolf Wolf
• Sunspot observations by Charles Malapert during the period 1618-1626: a key dataset to understand solar activity before the Maunder minimum
• Reconstruction of the Sunspot Number Source Database and the 1947 Zurich Discontinuity
• The Celestial Sign in the Anglo-Saxon Chronicle in the 770s: Insights on Contemporary Solar Activity
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• Iterative construction of the optimal sunspot number series