Relationship between the Sunspot Number and Active Day Fraction: An Application for the Maunder Minimum

Carrasco, V. M. S.; Llera, José Antonio; Aparicio, A. J. P.; Gallego, M. C.; Vaquero, J. M.

doi:10.3847/1538-4357/ac7045

Cited by 5 publications

(8 citation statements)

References 49 publications

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“…It has some particular characteristics with respect to other periods of solar activity. The solar activity level in this period (1645-1715) was abnormally low (Carrasco et al 2015(Carrasco et al , 2021(Carrasco et al , 2022aUsoskin et al 2015;Vaquero et al 2015b;Hayakawa et al 2021b). Some of the other particularities of this period were, for example, a strong hemispheric asymmetry since sunspots were observed mainly in the southern hemisphere (Ribes & Nesme-Ribes 1993;Hayakawa et al 2021c) and an apparent loss of coronal streamers (Hayakawa et al 2021d).…”

Section: Introductionmentioning

confidence: 82%

“…We acknowledge that these are raw data. Also, we note that another perspective on the solar activity level and date of the maximum amplitude is obtained in Section 5 using the active day fraction method described by Carrasco et al (2022a).…”

Section: A New Revision Of the Group Countsmentioning

confidence: 99%

“…We have estimated the annual sunspot number for the period 1716-1726 from the calculation of the active day fraction using the group number database by Vaquero et al (2016) including our new counting from Rost's and Alischer's observations. We have followed the methodology proposed by Carrasco et al (2022a) to estimate sunspot number values from the active day fraction. The best fit found by Carrasco et al (2022a) for that estimation (only valid for active day fraction values <100%) is with the following third-degree polynomial:…”

Section: An Estimation Of the Sunspot Number For The Period 1716-1726mentioning

confidence: 99%

“…We have followed the methodology proposed by Carrasco et al (2022a) to estimate sunspot number values from the active day fraction. The best fit found by Carrasco et al (2022a) for that estimation (only valid for active day fraction values <100%) is with the following third-degree polynomial:…”

Section: An Estimation Of the Sunspot Number For The Period 1716-1726mentioning

confidence: 99%

“…To contextualize how the transition of solar activity was between the end of the Maunder Minimum (Solar Cycle −4) to that after the Maunder Minimum (Solar Cycle −3), we have composed a series including the sunspot number values estimated by Carrasco et al (2022a) for Solar Cycle −4 (1700-1715) and those estimated in this work for Solar Cycle −3 (1716Cycle −3 ( -1726. Both works estimate the sunspot number from the active day fraction using the database by Vaquero et al (2016).…”

Section: Solar Activity In Solar Cycles −3 and −4mentioning

confidence: 99%

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Understanding Solar Activity after the Maunder Minimum: Sunspot Records by Rost and Alischer

Carrasco,

Aparicio,

Chatzistergos

et al. 2024

ApJ

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The Maunder Minimum was a period with significantly reduced solar activity between 1645 and 1715, approximately. The transition between the low solar activity in the Maunder Minimum and the subsequent “normal” regime of solar activity was gradual. However, there are discrepancies in the solar activity level from sunspot number indices and solar activity proxies in that period. Among the contemporaneous observers, Johann L. Rost and Sebastian Alischer were two key sunspot observers to understand the solar activity in this transition just after the Maunder Minimum. We have revised all their sunspot records, counting the number of groups and individual sunspots to derive reliable data for the solar activity level for the period 1716–1726. We found significant misinterpretations of the sunspot group counting assigned to these astronomers in the existing group number databases. Our new group sunspot counting significantly reduces the number of groups for Rost and Alischer’s observations compared to entries in existing databases. Furthermore, our sunspot number estimates (obtained from the active day fraction methodology) of the maximum amplitude of Solar Cycles −3 and −4 are significantly lower than the amplitudes according to the official sunspot number, but they are compatible with sunspot number values obtained from solar activity proxies such as radioisotopes. Our result would imply that solar activity after the Maunder Minimum recovered more gradually and with a lower intensity than previously considered.

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Section: Introductionmentioning

confidence: 82%

Section: A New Revision Of the Group Countsmentioning

confidence: 99%

Section: An Estimation Of the Sunspot Number For The Period 1716-1726mentioning

confidence: 99%

Section: An Estimation Of the Sunspot Number For The Period 1716-1726mentioning

confidence: 99%

Section: Solar Activity In Solar Cycles −3 and −4mentioning

confidence: 99%

See 3 more Smart Citations

Understanding Solar Activity after the Maunder Minimum: Sunspot Records by Rost and Alischer

Carrasco,

Aparicio,

Chatzistergos

et al. 2024

ApJ

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Recalibration of the Sunspot-Number: Status Report

et al. 2023

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We report progress on the ongoing recalibration of the Wolf sunspot number ($S_{\mathrm{N}}$ S N ) and group-sunspot number ($G_{\mathrm{N}}$ G N ) following the release of version 2.0 of $S_{\mathrm{N}}$ S N in 2015. This report constitutes both an update of the efforts reported in the 2016 Topical Issue of Solar Physics and a summary of work by the International Space Science Institute (ISSI) International Team formed in 2017 to develop optimal $S_{\mathrm{N}}$ S N and $G_{\mathrm{N}}$ G N reconstruction methods while continuing to expand the historical sunspot-number database. Significant progress has been made on the database side while more work is needed to bring the various proposed $S_{\mathrm{N}}$ S N and (primarily) $G_{\mathrm{N}}$ G N reconstruction methods closer to maturity, after which the new reconstructions (or combinations thereof) can be compared with (a) “benchmark” expectations for any normalization scheme (e.g., a general increase in observer normalization factors going back in time), and (b) independent proxy data series such as F10.7 and the daily range of variations of Earth’s undisturbed magnetic field. New versions of the underlying databases for $S_{\mathrm{N}}$ S N and $G_{\mathrm{N}}$ G N will shortly become available for years through 2022 and we anticipate the release of the next versions of these two time series in 2024.

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Sunspot positions from observations by Flaugergues in the Dalton Minimum

Illarionov

Arlt

2023

Monthly Notices of the Royal Astronomical Society

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French astronomer Honoré Flaugergues compiled astronomical observations in a series of hand-written notebooks for 1782–1830, which are preserved at Paris Observatory. We reviewed these manuscripts and encoded the records that contain sunspot measurements into a numerical table for further analysis. All measurements are timings and we found three types of measurements allowing the reconstruction of heliographic coordinates. In the first case, the Sun and sunspots cross vertical and horizontal wires, in the second case, one vertical and two mirror-symmetric oblique wires, and in the third case, a rhombus-shaped set of wires. Additionally, timings of two solar eclipses also provided a few sunspot coordinates. As a result, we present the time–latitude (butterfly) diagram of the reconstructed sunspot coordinates, which covers the period of the Dalton Minimum and confirms consistency with those of Derfflinger and Prantner. We identify four solar cycles in this diagram and discuss the observed peculiarities as well as the data reliability.

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Relationship between the Sunspot Number and Active Day Fraction: An Application for the Maunder Minimum

Cited by 5 publications

References 49 publications

Understanding Solar Activity after the Maunder Minimum: Sunspot Records by Rost and Alischer

Understanding Solar Activity after the Maunder Minimum: Sunspot Records by Rost and Alischer

Recalibration of the Sunspot-Number: Status Report

Sunspot positions from observations by Flaugergues in the Dalton Minimum

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