33 citations · 87 across the 3 of their papers we have counts for
3 papers
Reanalyses of the Sunspot Observations of Fogelius and Siverus: Two "Long-Term" Observers during the Maunder Minimum
Hisashi Hayakawa, Tomoya Iju, Shoma Uneme +3
The solar activity during the Maunder Minimum (MM; 1645 -- 1715) has been considered significantly different from the one captured in modern observations, in terms of sunspot group…
Historical Auroras in the 990s: Evidence for Great Magnetic Storms
Hisashi Hayakawa, Harufumi Tamazawa, Yurina Uchiyama +5
Recently, a significant carbon-14 enhancement in the year 994 in tree rings has been found, suggesting an extremely large cosmic ray flux event during a short period. The origin of…
The earliest drawings of datable auroras and a two-tail comet from the Syriac Chronicle of Zūqnīn
Hisashi Hayakawa, Yasuyuki Mitsuma, Yasunori Fujiwara +7
People have probably been watching the sky since the beginning of human history. Observers in pre-telescopic ages recorded anomalous events and these astronomical records in the hi…