98 citations · 275 across the 11 of their papers we have counts for
11 papers
Stephan Prantner's Sunspot Observations during the Dalton Minimum
Hisashi Hayakawa, Shoma Uneme, Bruno P. Besser +2
In addition to regular Schwabe cycles (~ 11 years), solar activity also shows longer periods of enhanced or reduced activity. Of these, reconstructions of the Dalton Minimum provid…
Daniel Mögling's sunspot observations in 1626 - 1629: A manuscript reference for the solar activity before the Maunder Minimum
Hisashi Hayakawa, Tomoya Iju, Koji Murata +1
The sunspot groups have been observed since 1610 and their numbers have been used for evaluating the amplitude of solar activity. Daniel Mögling recorded his sunspot observations f…
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…
SMART/SDDI Filament Disappearance Catalogue
Daikichi Seki, Kenichi Otsuji, Takako T. Ishii +8
This paper describes a new SMART/SDDI Filament Disappearance Catalogue, in which we listed almost all the filament disappearance events that the Solar Dynamics Doppler Imager (SDDI…
Thaddäus Derfflinger's sunspot observations during 1802-1824: A primary reference to understand the Dalton Minimum
Hisashi Hayakawa, Bruno P. Besser, Tomoya Iju +5
As we are heading towards the next solar cycle, presumably with a relatively small amplitude, it is of significant interest to reconstruct and describe the past grand minima on the…
Sunspot Observations by Hisako Koyama: 1945-1996
Hisashi Hayakawa, Frédéric Clette, Toshihiro Horaguchi +4
The sunspot record is the only observational tracer of solar activity that provides a fundamental, multi-century reference. Its homogeneity has been largely maintained with a succe…
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…
Revisiting Kunitomo's Sunspot Drawings during 1835-1836 in Japan
Masashi Fujiyama, Hisashi Hayakawa, Tomoya Iju +7
We revisit the sunspot drawings made by the Japanese astronomer Kunitomo Toubei during 1835-1836 and recount the sunspot group number for each image. There are two series of drawin…
Relationship Between Solar Wind Speed and Coronal Magnetic Field Properties
Ken'ichi Fujiki, Munetoshi Tokumaru, Tomoya Iju +2
We have studied the relationship between the solar-wind speed and the coronal magnetic-field properties (a flux expansion factor [] and photospheric magnetic-field strengt…
Plasma distribution of Comet ISON (C/2012 S1) observed using the radio scintillation method
Tomoya Iju, Shinsuke Abe, Munetoshi Tokumaru +1
We report the electron density in a plasma tail of Comet ISON (C/2012 S1) derived from interplanetary scintillation (IPS) observations during November 1--28, 2013. Comet ISON showe…
Radial Speed Evolution of Interplanetary Coronal Mass Ejections During Solar Cycle 23
Tomoya Iju, Munetoshi Tokumaru, Ken'ichi Fujiki
We report radial speed evolution of interplanetary coronal mass ejections (ICMEs) detected by the SOHO/LASCO coronagraph, interplanetary scintillation (IPS) at 327 MHz, and in-situ…