33 citations · 262 across the 17 of their papers we have counts for
6 papers · 1 filter
Solar ALMA observations: constraining the chromosphere above sunspots
Maria Loukitcheva, Kazumasa Iwai, Sami K. Solanki +2
We present the first high-resolution Atacama Large Millimeter/Submillimeter Array (ALMA) observations of a sunspot at wavelengths of 1.3 mm and 3 mm, obtained during the solar ALMA…
Variation of Solar Microwave Spectrum in the Last Half Century
M. Shimojo, K. Iwai, A. Asai +3
The total solar fluxes at 1, 2, 3.75, and 9.4 GHz were observed continuously from 1957 to 1994 at Toyokawa, and from 1994 until now at Nobeyama, Japan with the current Nobeyama Rad…
Polarization Characteristics of Zebra Patterns in Type IV Solar Radio Bursts
Kazutaka Kaneda, H. Misawa, K. Iwai +4
The polarization characteristics of zebra patterns (ZPs) in type IV solar bursts were studied. We analyzed 21 ZP events observed by the Assembly of Metric-band Aperture Telescope a…
OCTAD-S: Digital Fast Fourier Transform Spectrometers by FPGA
Kazumasa Iwai, Yûki Kubo, Hiromitsu Ishibashi +5
We have developed a digital fast Fourier transform (FFT) spectrometer made of an analog-to-digital converter (ADC) and a field-programmable gate array (FPGA). The base instrument h…
ALMA Discovery of Solar Umbral Brightness Enhancement at λ=3 mm
Kazumasa Iwai, Maria Loukitcheva, Masumi Shimojo +2
We report the discovery of a brightness enhancement in the center of a large sunspot umbra at a wavelength of 3 mm using the Atacama Large Millimeter/sub-millimeter Array (ALMA). S…
First ALMA Observation of a Solar Plasmoid Ejection from an X-ray Bright Point
M. Shimojo, H. S. Hudson, S. M. White +2
Eruptive phenomena such as plasmoid ejections or jets are an important feature of solar activity with the potential for improving our understanding of the dynamics of the solar atm…