Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Astrophysical Journal  

Solar activity generally exhibits cyclic behavior in terms of sunspot group number and sunspot positions every ≈11 yr. These sunspot data have therefore played key roles in numerous analyses of solar-terrestrial physics. However, their reconstructions prior to the 1830s have remained controversial and included significant data gaps, especially from the 1720s to the 1740s. Therefore, this study reviewed contemporary sunspot observations for 1727-1748 to add several forgotten records by Van Coesfelt in 1728-1729, Dûclos in 1736, Martin in 1737, and Cassini and Maraldi in 1748. On the basis of these records, this study revised the sunspot group number and newly derived the sunspot positions in this interval. The results show clearer solar cycles in sunspot group number than those of previous studies and indicate regular solar cycles with limited hemispheric asymmetry over Solar Cycles 0 to −2. The sunspot positions also show sunspot groups mostly at heliographic latitude φ fulfilling ∣φ∣ < 35° in both solar hemispheres, with slight equatorward motions. Furthermore, the solar minima between Solar Cycles −2 and −1 and between Solar Cycles −1 and 0 have been located around 1733.5 ± 0.5 and 1743 ± 0.5, indicating cycle lengths of 11.7 ± 0.5 yr and 10.0 ± 1.0 yr, respectively. Our results provide a chronological missing link between the Maunder Minimum and the regular solar cycles observed since Staudach’s observations from 1749 onward. This lets us better understand the transition of solar activity from the grand minimum to the regular solar cycles.

DOI： 10.3847/1538-4357/ac6671

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Publications of the Astronomical Society of the Pacific  

As one of the greatest astronomical spectacles, total solar eclipses have long been a subject of scientific interest and have been recorded by numerous civilizations over the millennia. These records are an essential reference for constraining and reconstructing Earth’s variable rotation (ΔT) prior to the 17th century. However, ΔT reconstructions for the 4th-7th centuries have significant uncertainties, mainly owing to a data scarcity. Here, we analyze Byzantine historical sources with reports of total solar eclipses along the Eastern Mediterranean coasts and add probable ΔT constraints on their basis. We examined five cases of total solar eclipses in 346, 418, 484, 601, and 693 CE, identified times and locations of the observations, and compared them with the existing ΔT spline curve to derive new ΔT constraints. Our results probably tighten ΔT variability in 346 CE, show a larger ΔT range in 418 CE, and give smaller ΔT ranges in 484, 601, and 693 CE. Our study tightens the existing ΔT variations and occasionally support some ΔT constraints that slightly depart from the ΔT spline curve in the latest reconstructions. Our results are consistent with contemporary ΔT constraints from other studies and offer an improved understanding of Earth’s variable rotation.

DOI： 10.1088/1538-3873/ac6b56

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/1538-4357/ac2601

DOI： 10.3847/1538-4357/ac2601

Publisher：Advances in Space Research  

Historical auroral reports extend our knowledge of solar eruptions and long-term solar variability in the millennial time scale beyond the chronological coverage of instrumental observations, in the decadal to centennial time scales. Such chronological extensions benefit the scientific community, increasing the number of case studies on extreme space weather events with lower frequency but higher potential impact on modern technological infrastructure. So far, the earliest known datable reports of candidate aurorae have reached back to the 7th century BCE. Beyond this time series, we have analysed a celestial report in the Chinese Bamboo Annals that has attracted little scientific interest, probably owing to the controversial interpretations for the physical identity and the chronology of the event. Our philological analysis establishes its probable auroral nature. The textual description can be compared with early modern accounts of visual auroral observations for the multi-colour aurorae. We have located the observational site around Hàojīng (N34°14′, E108°46′) and dated the event to 977 ± 1 or 957 ± 1 BCE. On this basis, we have computed the equatorward extension of the auroral visibility as ≤39.0° in magnetic latitude and reconstructed the equatorward boundary of the auroral oval as ≤45.5° in invariant latitude. Our investigations empirically associate this candidate aurora with an extreme geomagnetic storm. We have compared this space weather event with proxy-based reconstructions of long-term solar variability and characterised it as a unique space-weather reference before the Neo-Assyrian Grand Minimum (alternatively Homeric Grand Minimum) in ca. 810 – 720 BCE.

DOI： 10.1016/j.asr.2022.01.010

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/1538-4357/abee1b

DOI： 10.3847/1538-4357/abee1b

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/2041-8213/ab6a18

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/1538-4357/ab65c9

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1029/2019SW002269

DOI： 10.1029/2019SW002269

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Geoscience Data Journal  

Historical weather records from Europe indicate that the Earth experienced substantial climate variability, which caused, for instance, the Little Ice Age and the global crisis in the period between the 14th and 19th centuries. However, it is still unclear how global this climate variability was because of the scarce meteorological data availability in other regions including East Asia, especially around the 17th century. In this context, Seungjeongwon Ilgi, a daily record of the Royal Secretariat of the Joseon Dynasty of Korea, is a precious source of historical meteorological records for the Korean Peninsula, as it covers 288 years of weather observations made during 1623–1910. We used the digital database of Seungjeongwon Ilgi to construct a machine-readable weather condition dataset. To this end, we extracted valid weather information from the original weather description text and compiled them into pre-defined weather categories. Additionally, we attempted to improve the usability of dataset by converting the reported dates in the traditional calendar system to those in the Gregorian calendar. Finally, we outlined promising implications of this dataset for meteorological and climatological studies, while describing the limitations of the dataset. Overall, future studies focusing on the climate and weather of the past could use this meteorological database for investigating long-term climate variability. Our datasets are publicly available at 10.5281/zenodo.8382243.

DOI： 10.1002/gdj3.227

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Authorship：Corresponding author   Language：English   Publisher：Geoscience Data Journal  

DOI： 10.1002/gdj3.243

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Space Weather and Space Climate  

A study is made of the intensity of the Carrington magnetic storm of September 1859 as inferred from visual measurements of horizontal-component geomagnetic disturbance made at the Colaba observatory in India. Using data from modern observatories, a lognormal statistical model of storm intensity is developed, to characterize the maximum-negative value of the storm-Time disturbance index (maximum a-Dst) versus geomagnetic disturbance recorded at low-latitude observatories during magnetic storms. With this model and a recently published presentation of the Colaba data, the most likely maximum a-Dst of the Carrington storm and its credibility interval are estimated. A related model is used to examine individual Colaba disturbance values reported for the Carrington storm. Results indicate that only about one in a million storms with maximum a-Dst like the Carrington storm would result in local disturbance greater than that reported from Colaba. This indicates that either the Colaba data were affected by magnetospheric-ionospheric current systems in addition to the ring current, or there might be something wrong with the Colaba data. If the most extreme Colaba disturbance value is included in the analysis, then, of all hypothetical storms generating the hourly average disturbance recorded at Colaba during the Carrington storm, the median maximum a-Dst = 964 nT, with a 68% credibility interval of [855,1087] nT. If the most extreme Colaba disturbance value is excluded from the analysis, then the median maximum a-Dst = 866 nT, with a 68% credibility interval of [768,977] nT. The widths of these intervals indicate that estimates of the occurrence frequency of Carrington-class storms are very uncertain, as are related estimates of risk for modern technological systems.

DOI： 10.1051/swsc/2024015

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Monthly Notices of the Royal Astronomical Society  

Our knowledge of the centennial solar variability is largely based on the time series of international sunspot number (SN), a composite index based on multiple visual sunspot observers’ records from the 18th century onward and maintained by the World Data Center (WDC) ‘Sunspot Index and Long-term Solar Observations’ (SILSO). However, over the period 1919–1944, our capacity to diagnose the homogeneity of this time series is currently limited, because most of the archived source data of the Zürich Observatory were never published over that interval and are presently still missing. Therefore, it is essential to recover any long-duration series from individual sunspot observers active during this period to bridge this Zürich data gap. In this context, Katsue Misawa has conducted regular sunspot observations from 1921 to 1934 (mean coverage of 25.4 days per month), which were not accessible for the Zürich Observatory and thus form a valuable addition to the data base maintained by the WDC–SILSO. In this study, we digitized his observational records, documented his observing technique, and reconstructed his total and hemispheric SNs. We compared his data with the international SN (current version V2) and evaluated their stability. Misawa’s data series generally agrees well with SN V2. However, Misawa’s data show a significant transitory drift in 1925–1928 against the SN V2, when the Zürich pilot observer changed from Alfred Wolfer to William Otto Brunner.

DOI： 10.1093/mnras/stad2791

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Authorship：Lead author,　Corresponding author   Language：English   Publisher：Monthly Notices of the Royal Astronomical Society  

Datable graphical records of total solar eclipses allow us to assess contemporaneous variability of Earth's rotation speed, solar coronal structure, and solar-wind conditions. Such graphical records were studied back to the early 18th century. Here, we examine Matthew Paris' medieval manuscript, an eyewitness account of a total solar eclipse just after local sunrise on 1230 May 14, to analyse his drawings for this eclipse. We philologically identify his observational site as St. Albans and compute local eclipse visibility. To locate St. Albans in the totality path, our analysis requires an accumulative error in time due to the variation in the Earth's rate of rotation, ΔT, in the range 394 s < ΔT < 764 s (loose scenario), slightly revising the latest published ΔT spline curve. The eclipsed Sun sould have been visible after local sunrise if we set the ΔT margins to 394 s < ΔT < 659 s (strict scenario), which requires a further slight modification of the latest ΔT spline curve. Matthew Paris' drawing of the total solar eclipse showed streamer-like structures similar to solar-minimum-type coronal streamers, consistent with the local tilt of the apparent solar equator. This is morphologically consistent with the minimum-type solar coronal streamers predicted from the open solar flux reconstructed from the14C data set. This record potentially demonstrates a similarity in solar cycles between the 'Medieval Grand Maximum' and modern solar cycles. Collectively, historical eclipse records could be used as spot references for Earth's rotation speed, solar coronal dynamics, and background solar dynamo activity on a millennial time-scale.

DOI： 10.1093/mnras/stad3874

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Space Weather  

Dedicated scientific measurements of the strength and direction of the Earth's magnetic field began at Greenwich and Kew observatories in London, United Kingdom, in the middle of the nineteenth century. Using advanced techniques for the time, collimated light was focussed onto mirrors mounted on free-swinging magnetized needles which reflected onto photographic paper, allowing continuous analog magnetograms to be recorded. By good fortune, both observatories were in full operation during the so-called Carrington storm in early September 1859 and its precursor storm in late August 1859. Based on digital images of the magnetograms and information from the observatory yearbooks and scientific papers, it is possible to scale the measurements to International System of Units (SI units) and extract quasi-minute cadence spot values. However, due to the magnitude of the storms, the periods of the greatest magnetic field variation were lost as the traces moved off-page. We present the most complete digitized magnetic records to date of the 10-day period from 25 August to 5 September 1859 encompassing the Carrington storm and its lesser recognized precursor on 28 August. We demonstrate the good correlation between observatories and estimate the instantaneous rate of change of the magnetic field.

DOI： 10.1029/2023SW003807

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Monthly Notices of the Royal Astronomical Society  

Within four centuries of sunspot observations, the Maunder Minimum (MM) in 1645–1715 has been considered a unique grand minimum with weak solar cycles in group numbers of sunspots and hemispheric asymmetry in sunspot positions. However, the early part of the MM (1645–1659) is poorly understood in terms of its source records and has accommodated diverse reconstructions of the contemporaneous group number. This study identified their source records, classidied them in three different categories (datable observations, general descriptions, and misinterpreted records), and revised their data. On this basis, we estimated the yearly mean group number using the brightest star method, derived the active day fraction (ADF), reconstructed the sunspot number based on ADF, and compared them with proxy reconstructions from the tree-ring data sets. Our results revised the solar activity in the early MM downward in yearly mean group numbers using the brightest star method and upward in the active day fraction and sunspot number estimates. Our results are consistent with the proxy reconstruction for 1645–1654 and show more realistic values for 1657–1659 (against the unphysical negative sunspot number). These records have paid little attention to sunspot positions, except for Hevelius’ report on a sunspot group in the northern solar hemisphere in 1652 April. Therefore, slight caveats are required to discuss if the sunspot positions are located purely in the southern solar hemisphere throughout the MM.

DOI： 10.1093/mnras/stad3922

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Monthly Notices of the Royal Astronomical Society  

Intense solar eruptions occasionally trigger extreme geomagnetic storms, expand the boundaries of the auroral oval, and facilitate equatorward extensions of the auroral visibility. It is important to analyse such events, to better understand the extremity of space weather and its impact on the technological infrastructure of the modern civilization. However, unlike other extreme geomagnetic storms, little is known about the auroral activity associated with the extreme geomagnetic storm on 15/16 July 1959, the second largest geomagnetic storm in the space age. This study acquired and analysed two Chinese accounts and one Russian account of auroral visibility at low (≤40°) magnetic latitudes (MLATs). These records allowed us to conservatively reconstruct the equatorward boundaries of the auroral visibility and the auroral oval at 27.4° MLAT and 35.4° invariant latitude, respectively. Our analysis chronologically contextualized these auroral records slightly before the peak of the extreme geomagnetic storm. Moreover, their coloration indicates the excitations of, at least, nitrogen at 427.8 nm and oxygen at 557.7 nm at these low MLATs. Our results allow us to contextualize this extreme geomagnetic storm within other extreme events, based on the equatorward boundary of the auroral oval, thereby facilitating the improvement in existing empirical models for correlations of the auroral extension and the storm intensity.

DOI： 10.1093/mnras/stad3556

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：De Medio Aevo  

This paper critically reexamines two candidate records of the supernova of 1054 CE (SN 1054) that allegedly came from Constantinople, integrating historical and astronomical analyses. East Asian records documented SN 1054 in detail and formed a basis for astronomical discussions about this supernova. In contrast, few reports of SN 1054 from Western Eurasia (Europe and West Asia) are known. The majority of such alleged reports have been rejected on the basis of philological and astronomical discussions. This study scrutinizes two potential accounts of SN 1054. The first is Ibn Buṭlān’s account, as cited in a later work. The second is a specific class of Byzantine gold coin issued in Constantinople, which may have commemorated SN 1054. Our reanalysis of Ibn Buṭlān’s record questions its connection to Constantinople. We also challenge speculation regarding the Byzantine coin, analysing contemporary historical and numismatic backgrounds. The paper also compares these accounts with the reconstructed SN light curve and modern astronomical calculations to assess the astronomical aspect of these records.

DOI： 10.5209/dmae.94559

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Space Weather and Space Climate  

Cosmogenic nuclides - 14C from tree rings and 10Be and 36Cl from ice cores serve as an effective proxy for past extreme solar energetic particle (SEP) events. After identifying the first signature of an extreme SEP event in 774 CE, several candidates have been found in these proxy archives, such as 993 CE, 660 BCE, and 7176 BCE. Their magnitudes have been estimated to be tens of times larger than that of the largest SEP event ever observed since the 1950s. Although a detailed survey of such extreme SEP events is ongoing, the detection of intermediate-sized SEP events that bridge the gap between modern observations and extreme events detected in cosmogenic nuclides has not progressed sufficiently, primarily because of the uncertainties in cosmogenic nuclide data. In this study, we measured 14C concentrations in tree rings in the 19th century (1844- 1876 CE) to search for any increases in 14C concentrations corresponding to intermediate-size extreme SEP events. We utilized Alaskan tree-ring samples cut into early and latewoods to suppress the potential seasonal variations in intra-annual 14C data. Notably, no significant 14C variations were observed between early and latewoods (0.0 ± 0.3°), and the annual resolution 14C data series displayed an error of ~ 0.8°. Over the entire study period, no significant increase in 14C concentrations characterized by other candidates of extreme SEP events such as the 774 CE event was detected in the annual 14C data. The present result imposes a constraint on the SEP fluence when the largest class of recorded solar storms occurred (especially those in 1859 CE and 1872 CE).

DOI： 10.1051/swsc/2023030

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Space Science Reviews  

The Sun is magnetically active and often produces eruptive events on different energetic and temporal scales. Until recently, the upper limit of such events was unknown and believed to be roughly represented by direct instrumental observations. However, two types of extreme events were discovered recently: extreme solar energetic particle events on the multi-millennial time scale and super-flares on sun-like stars. Both discoveries imply that the Sun might rarely produce events, called extreme solar events (ESE), whose energy could be orders of magnitude greater than anything we have observed during recent decades. During the years following these discoveries, great progress has been achieved in collecting observational evidence, uncovering new events, making statistical analyses, and developing theoretical modelling. The ESE paradigm lives and is being developed. On the other hand, many outstanding questions still remain open and new ones emerge. Here we present an overview of the current state of the art and the forming paradigm of ESE from different points of view: solar physics, stellar–solar projections, cosmogenic-isotope data, modelling, historical data, as well as terrestrial, technological and societal effects of ESEs. Special focus is paid to open questions and further developments. This review is based on the joint work of the International Space Science Institute (ISSI) team #510 (2020–2022).

DOI： 10.1007/s11214-023-01018-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal for the History of Astronomy  

This study analysed four records of questionable authenticity of total solar eclipses between the fourth and sixth centuries CE in Byzantine narrative sources. As it has been difficult to evaluate their credibility, they have not been utilised in modern astronomical studies. Three records originated in the fourth century, all of which have problems with accurate dating and provenance. The one remaining record concerns the total solar eclipse on 512 June 29. This study first reveals the problems with and questions around the reliability of all these records from astronomical perspectives based on the latest ΔT spline curve and recently proposed ΔT constraints. It then explores their philological and historical contexts to understand how and why these records were written.

DOI： 10.1177/00218286231167185

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Geoscience Data Journal  

Individual sunspot observations have formed a ground basis of international sunspot number, a unique reference for long-term solar variability in the centennial timescale. The original datasets were subjected to exploitations and analyses upon the recalibrations of the sunspot number series. In this context, this study reviewed and analysed original sunspot records and their databases in the Kawaguchi Science Museum (KSM) in Japan. KSM hosts sunspot drawings and logbooks from 1972 to 2013. This dataset has a longer chronological coverage than what was known to the scientific community (1981–2010). These records have been digitized and publicized in a museum database, which allows users to access individual sunspot drawings and numerical data in KSM logbooks. These records are highly homogeneous as a single observer's dataset (Hitoshi Takuma), who used a 15-cm refractor at the Kawaguchi Juvenile Museum in 1972–2003 and a 20-cm refractor at KSM in 2003–2013. We also reviewed the Takuma data series, his monthly observation days (21.3 days/month), sunspot number in the whole disk and each hemisphere, and sunspot positions in a butterfly diagram. We also assessed Takuma's data stability in comparison with the international sunspot number and reference datasets of the SILSO. Takuma's data appear stable until 2003, when he changed the observation site and instrument. His data stability was quantitatively compared with the SILSO reference datasets, confirming the substantial long-term stability of the data and establishing its reliability as an alternative reference for sunspot number recalibration.

DOI： 10.1002/gdj3.158

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Solar Physics  

The focus of this study is to reveal the reason behind a scale problem detected around 1849 in the historical version of the International Sunspot Number Series, i.e. version 1 (Leussu et al. in Astron. Astrophys.559, A28, 2013; Friedli in Solar Phys.291, 2505, 2016). From 1826 to 1848 Heinrich Schwabe’s observations were considered primary by Rudolf Wolf, and a shift of primary observer from Schwabe to Wolf in 1849 seems to have led to an inconsistency in the Sunspot Number series. In this study we benefited from various datasets, the most important being Schwabe’s raw counts from the Mittheilungen (Prof. Wolf’s Journals) that have been digitised at the Royal Observatory of Belgium between 2017 and 2019. We provide a robust quantification of the detected problem by using classic algebraic calculations, but also different methods such as a method inspired by Lockwood et al. (J. Geophys. Res.119(7), 5172, 2014), hence assigning a modern k-factor to Schwabe’s observations before 1849. We also assess the implications of this 1849 inconsistency on the International Sunspot Number series (Versions 1 and 2) before and after 1849.

DOI： 10.1007/s11207-022-02103-4

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Solar Cycle 19 was probably the greatest solar cycle over the last four centuries and significantly disrupted the solar-terrestrial environments with a number of solar eruptions and resultant geomagnetic storms. At its peak, the International Geophysical Year (IGY: 1957–1958) was organised under international collaborations and benefitted scientific developments, capturing multiple unique extreme space weather events including the third and fourth greatest geomagnetic storms in the space age. In this article, we review and analyse original records of Japanese auroral observations around the IGY. These observations were organised by Masaaki Huruhata in collaboration with professional observatories and citizen contributors. We have digitised and documented these source documents, which comprise significant auroral displays in March 1957 (minimum Dst = −255 nT), September 1957 (minimum Dst = −427 nT), and February 1958 (minimum Dst = −426 nT). These records allow us to visualise temporal and spatial evolutions of these auroral displays, reconstruct their equatorward auroral boundaries down to 41.5°, 38.3°, and 33.3° in invariant latitudes, and contextualise their occurrences following contemporary geomagnetic disturbances. Our results have been compared with significant auroral displays during other extreme space weather events. These aurorae generally showed reddish colourations occasionally with yellowish rays. Their colourations are attributed to reddish oxygen emission and its mixture with greenish oxygen emission. Overall, these archival records provide the references for future discussions on the auroral activities during the uniquely intense and extreme space weather events.

DOI： 10.1002/GDJ3.140

CiNii Research

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/pasj/psac064

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Monthly Notices of the Royal Astronomical Society  

In late 1940 March, at least five significant solar flares were reported. They likely launched interplanetary coronal mass ejections (ICMEs), and were associated with one of the largest storm sudden commencements (SSCs) since 1868, resulting in space weather hazards that would have significant societal impacts should it occur today. The initial solar activity is associated with a solar proton event. Afterwards, another flare was reported in the eastern solar quadrant (N12 E37-38) at 11:30-12:30 ut on March 23, with significant magnetic crochets (up to ≈ |80| nT at Eskdalemuir) during 11:07-11:40 ut. On their basis, we conservatively estimate the required energy flux of the source solar flare as X35 ± 1 in soft X-ray class. The resultant ICMEs caused enormous SSCs (up to >425 nT recorded at Tucson) and allowed us to estimate an extremely inward magnetopause position (estimated magnetopause stand-off position ≈3.4 RE). The time series of the resultant geomagnetic storm is reconstructed using a Dst estimate, which peaked at 20 ut on March 24 at ≈ -389 nT. Around the storm main phase, the equatorward boundary of the auroral oval extended ≤46.3° in invariant latitudes. This sequence also caused a solar proton event and Forbush decrease (≈3 per cent). These sequences indicate pile-up of multiple ICMEs, which even achieved a record value of inward magnetopause position. Our analyses of this historical pioneer event bring more insights into possible serious space weather hazards and provide a quantitative basis for future analyses and predictions.

DOI： 10.1093/mnras/stab3615

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Publications of the Astronomical Society of Japan  

The Dalton minimum is considered to be one of the unique solar activity periods that have been captured in direct sunspot observations since 1610. Specifically, the solar magnetic field in this period is of great interest. Derfflinger and Prantner's sunspot observations of 1802-1824 and 1800-1844 are the most important references for this period. To understand the solar magnetic activity in the Dalton minimum, it is important to estimate the latitude/longitude distribution of the sunspots and the sunspot areas for that duration. In this study, we analyze Derfflinger and Prantner's sunspot drawings to determine the sunspot parameters, particularly the sunspot area. We find that the sunspot areas obtained from Derfflinger's drawings are overemphasized by a factor of eight relative to those derived from modern observations. We also analyze Prantner's sunspot drawings to validate our analysis of Derfflinger's drawings. Further, we generate solar magnetograms from Derfflinger's sunspot drawings using a deep-learning model based on conditional generative adversarial networks. Our analysis of these sunspot areas will provide important information for restoring the magnetograms during the Dalton minimum.

DOI： 10.1093/pasj/psac032

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Language：English   Publisher：Monthly Notices of the Royal Astronomical Society  

This is an erratum for our article Carrasco et al. ( 2021 ): 'Strong evidence of low levels of solar activity during the Maunder Minimum'. The error margins for the active day fraction of fig. 1 (bottom panel) were wrongly plotted. On the one hand, there were not error margins associated to the active day fraction for the years 1709-1715. On the other hand, the error margins represented with the active day fraction in the year range of 1652-1708 are not correct. For example, the error margin plotted with the active day fraction of 1708 were actually the error margins calculated for 1715, those plotted with the active day fraction of 1707 are in fact the error margins of 1714 and so on. This mistake does not hav e an y impacts on the remaining calculations in this article. Here, we pro vide an update of Fig. 1 with corrected error margins. DATA AVAILABILITY STATEMENT Data used in this work on the number of groups recorded by any observer during the Maunder Minimum is available through Vaquero et al. ( 2016 ) and, in particular, those from from the Eimmart archives including Johann Heinrich M üller's observations are available through Hayakawa et al. ( 2021 ). The annual values of the international sunspot number index (version 2) are available on the website of the Sunspot Index and Long-term Solar Observations ( http://www.sidc.be/silso/). (Figure presented).

DOI： 10.1093/mnras/stac901

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/gdj3.140

DOI： 10.1002/gdj3.140

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Other Link： https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/gdj3.140

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/pasj/psab088

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Authorship：Last author   Language：English  

DOI： 10.1007/s11207-021-01905-2

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s11207-021-01880-8

DOI： 10.1007/s11207-021-01880-8

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/pasj/psab079

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/mnras/staa2965

DOI： 10.1093/mnras/staa2965

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Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1186/s40623-021-01486-1

DOI： 10.1186/s40623-021-01486-1

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/mnras/stab1155

DOI： 10.1093/mnras/stab1155

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1051/swsc/2021011

DOI： 10.1051/swsc/2021011

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/1538-4357/abc427

DOI： 10.3847/1538-4357/abc427

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1051/swsc/2020045

DOI： 10.1051/swsc/2020045

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/1538-4357/abb3c2

DOI： 10.3847/1538-4357/abb3c2

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/1538-4357/abd949

DOI： 10.3847/1538-4357/abd949

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/1538-4357/abdd34

DOI： 10.3847/1538-4357/abdd34

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DOI： 10.1051/swsc/2020035

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DOI： 10.1051/swsc/2020082

DOI： 10.1051/swsc/2020082

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DOI： 10.3847/1538-4357/abb772

DOI： 10.3847/1538-4357/abb772

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/pasj/psaa114

DOI： 10.1093/pasj/psaa114

Language：Japanese   Publisher：京都大学大学院理学研究科附属天文台  

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3847/1538-4357/abad93

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1029/2020SW002472

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DOI： 10.1093/mnras/staa1508

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DOI： 10.1029/2020JA028227

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DOI： 10.3847/1538-4357/ab9807

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1186/s40623-020-01249-4

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1186/s40623-020-01208-z

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.5194/hgss-11-81-2020

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/mnras/stz3345

DOI： 10.1088/2514-3433/ab404ach6

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DOI： 10.1088/2514-3433/ab404ach2

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DOI： 10.1088/2514-3433/ab404ach7

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DOI： 10.3847/2041-8213/ab42e4

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Publisher：Solar Physics  

DOI： 10.1007/s11207-019-1504-9

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Publisher：Solar Physics  

DOI： 10.1007/s11207-019-1429-3

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Publisher：Monthly Notices of the Royal Astronomical Society  

DOI： 10.1093/mnras/sty3196

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Publisher：Publications of the Astronomical Society of Japan  

DOI： 10.1093/pasj/psy066

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Event date： 2022.12

Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：オンライン  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：諏訪   Country：Japan  

Event date： 2022.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Nagoya   Country：Japan  

Event date： 2022.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Zagreb  

Event date： 2022.10

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：New Delhi   Country：India  

Event date： 2022.7

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Athens   Country：Greece  

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Athens   Country：Greece  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Venue：オンライン  

Event date： 2022.3

Language：English   Presentation type：Oral presentation (general)  

Venue：Rokua   Country：Finland  

Event date： 2022.3

Language：Japanese   Presentation type：Symposium, workshop panel (nominated)  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島大学  

Event date： 2022.2

Language：English   Presentation type：Oral presentation (general)  

Country：India  

Event date： 2021.9 - 2021.10

Language：English   Presentation type：Oral presentation (invited, special)  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都産業大学  

Event date： 2021.8

Language：English   Presentation type：Oral presentation (general)  

Venue：virtual  

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Language：English   Presentation type：Oral presentation (general)  

Language：Japanese   Presentation type：Oral presentation (general)  

Language：English   Presentation type：Oral presentation (invited, special)  

Author：Other 

Author：Other 

Author：Other 

Author：Other 

Author：Other