28 citations · 38 across the 2 of their papers we have counts for
4 papers
Temporal and Spatial Evolutions of a Large Sunspot Group and Great Auroral Storms around the Carrington Event in 1859
Hisashi Hayakawa, Yusuke Ebihara, David M. Willis +10
The Carrington event is considered to be one of the most extreme space weather events in observational history within a series of magnetic storms caused by extreme interplanetary c…
A Transit of Venus Possibly Misinterpreted as an Unaided-Eye Sunspot Observation in China on 9 December 1874
Hisashi Hayakawa, Mitsuru Sôma, Kiyotaka Tanikawa +6
Large sunspots can be observed with the unaided eye under suitable atmospheric seeing conditions. Such observations are of particular value because the frequency of their appearanc…
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…