29 citations · 84 across the 9 of their papers we have counts for
9 papers
Automated Sunspot Detection as an Alternative to Visual Observations
Yoichiro Hanaoka
We developed an automated method for sunspot detection using digital white-light solar images to achieve a performance similar to that of visual drawing observations in sunspot cou…
Polarization of the Corona Observed During the 2017 and 2019 Total Solar Eclipses
Yoichiro Hanaoka, Yoshiaki Sakai, Koichi Takahashi
We carried out polarimetric observations of the white-light corona during the total solar eclipses that occurred on 2017 August 21 and 2019 July 2, and successfully obtained data a…
Internetwork Magnetic Fields Seen in Fe I 1564.8 nm
Yoichiro Hanaoka, Takashi Sakurai
We studied the properties of internetwork magnetic fields in the solar photosphere taking advantage of full-disk Stokes maps of the \ion{Fe}{1} 1564.8 nm line, which were obt…
Synoptic solar observations of the Solar Flare Telescope focusing on space weather
Yoichiro Hanaoka, Takashi Sakurai, Ken'ichi Otsuji +2
The solar group at the National Astronomical Observatory of Japan is conducting synoptic solar observations with the Solar Flare Telescope. While it is a part of a long-term solar…
Infrequent Occurrence of Significant Linear Polarization in H Solar Flares
Tomoko Kawate, Yoichiro Hanaoka
We performed statistical and event studies of linear polarization in the H line during solar flares. The statistical study revealed that, among 71 H flares analyzed, includin…
Solar Coronal Jets Extending to High Altitudes Observed During the 2017 August 21 Total Eclipse
Yoichiro Hanaoka, Ryuichi Hasuo, Tsukasa Hirose +11
Coronal jets, which extend from the solar surface to beyond 2 , were observed in the polar coronal hole regions during the total solar eclipse on 2017 August 21. In a time…
Statistical Study of the Magnetic Field Orientation in Solar Filaments
Yoichiro Hanaoka, Takashi Sakurai
We have carried out a statistical study of the average orientation of the magnetic field in solar filaments with respect to their axes for more than 400 samples, based on data take…
Pre-eruption Oscillations in Thin and Long Features in a Quiescent Filament
Anand D. Joshi, Yoichiro Hanaoka, Yoshinori Suematsu +3
We investigate the eruption of a quiescent filament located close to an active region. Large-scale activation was observed in only half of the filament in the form of pre-eruption…
Coronal Mass Ejections Observed at the Total Solar Eclipse on 13 November 2012
Yoichiro Hanaoka, Jun Nakazawa, Osamu Ohgoe +2
We carried out white-light observations of the total solar eclipse on 13 November 2012 at two sites, where the totality occurred 35 minutes apart. We caught an ongoing coronal mass…