28 citations · 66 across the 6 of their papers we have counts for
5 papers
Analyses on Christoph Clavius' Reports of Total Solar Eclipses in 1560 and 1567: Key References for the Centennial Variations of the Earth's Rotation Speed and the Solar Radius
Hisashi Hayakawa, Mitsuru Sôma, Jean-Pierre Rozelot +4
Variations in solar radius (hereafter R_Sun) is a key reference for solar magnetic activity in time. The sunlight amount may have varied with R_Sun and had an effect on the Earth's…
Analyses on Wassenius' Report for Total Solar Eclipse in 1733: Quantifications of the Solar Radius and the Earliest Reported Prominences
Hisashi Hayakawa, Mitsuru Sôma, Noortje Peek +3
Total solar eclipses (TSEs) offer a unique opportunity to observe the solar atmosphere, detect limb phenomena, and accurately measure the solar radius. Following the TSE in 1733, W…
Variable Earth's Rotation Speed in the 14th to 16th Centuries: New ΔT Constraints from Chinese Eclipse Records
Hisashi Hayakawa, Mitsuru Sôma, Naiqi Li
Total solar eclipses are not only astronomical spectacles but also great astrophysical laboratories. Their historical records are particularly helpful for assessing the past variab…
Do the Chinese Astronomical Records Dated AD 776 January 12/13 Describe an Auroral Display or a Lunar Halo? A Critical Re-examination
F. Richard Stephenson, David M. Willis, Hisashi Hayakawa +4
The enhancement of carbon-14 in tree rings around AD 774/775 has generated wide interest in solar activity at that time. The historical auroral records have been examined criticall…
The Celestial Sign in the Anglo-Saxon Chronicle in the 770s: Insights on Contemporary Solar Activity
Hisashi Hayakawa, F. Richard Stephenson, Yuta Uchikawa +5
The anomalous concentration of radiocarbon in 774/775 attracted intense discussion on its origin, including the possible extreme solar event(s) exceeding any events in observationa…