Explanipedia

Concept of high-z gamma-ray bursts unraveling the dark ages and extreme space-time mission—HiZ-GUNDAM Open

Daisuke Yonetoku, Akihiro Doi, T. Mihara, Hideo Matsuhara, T. Sakamoto , et al. · 2025

CALET's sensitivity to electron cosmic-ray spectral and anisotropy signatures of the Vela SNR Open

Holger Motz, O. Adriani, Yosui Akaike, Katsuaki Asano, Y. Asaoka , et al. · 2025

The 157 Month Swift/BAT All-sky Hard X-Ray Survey Open

A. Y. Lien, H. A. Krimm, C. B. Markwardt, Kyuseok Oh, L. Marcotulli , et al. · 2025

The Burst Alert Telescope (BAT) on board the Neil Gehrels Swift Observatory has been serving as a survey instrument for the hard X-ray sky, and has detected thousands of X-ray sources (e.g., active galactic nuclei, X-ray binaries, etc). BA…

Detected Abundances of Nuclei Relative to 26Fe for Elements 14Si through 44Ru with CALET on the International Space Station Open

O. Adriani, Yosui Akaike, Katsuaki Asano, Y. Asaoka, E. Berti , et al. · 2025

The Calorimetric Electron Telescope (CALET), launched to the International Space Station (ISS) in 2015 August and continuously operating since, measures cosmic-ray (CR) electrons, nuclei, and gamma rays. CALET, with its 27 radiation length…

The 157-month Swift-BAT All-Sky Hard X-Ray Survey Open

A. Y. Lien, H. Krimm, C. B. Markwardt, Kyuseok Oh, L. Marcotulli , et al. · 2025

The Burst Alert Telescope (BAT) onboard the Neil Gehrels Swift observatory has been serving as a survey instrument for the hard X-ray sky, and has detected thousands of X-ray sources (e.g., AGNs, X-ray binaries, etc). BAT monitors these X-…

Characterization of a Peculiar Einstein Probe Transient EP240408a: An Exotic Gamma-Ray Burst or an Abnormal Jetted Tidal Disruption Event? Open

Brendan O’Connor, Dheeraj R. Pasham, Igor Andreoni, Jeremy Hare, Paz Beniamini , et al. · 2025

We present the results of our multiwavelength (X-ray to radio) follow-up campaign of the Einstein Probe transient EP240408a. The initial 10 s trigger displayed bright soft X-ray (0.5–4 keV) radiation with peak luminosity L X ≳ 10 49 (10 50…

New results obtained from CALET observations after 8 years of data collection on the International Space Station Open

S. Gonzi, O. Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka , et al. · 2024

The Calorimetric Electron Telescope (CALET) is a cosmic-ray observatory operating since October 2015 on the International Space Station. The primary scientific goals of the CALET mission include the investigation of the mechanism of cosmic…

Searching for the signature of fast radio burst by Swift/XRT X-ray afterglow light curve Open

Hsien-Chieh Shen, T. Sakamoto, Motoko Serino, Yuri Sato · 2024

A new type of cosmological transient, dubbed fast radio bursts (FRBs), was recently discovered. The source of FRBs is still unknown. One possible scenario of an FRB is the collapse of a spinning supra-massive neutron star. Zhang (2014, ApJ…

Radiation tolerance test and performance verification of pnCCD at high temperatures for future satellite mission HiZ-GUNDAM Open

Shuta Takahashi, M. Arimoto, Hatsune Goto, Ryuji Kondo, Daisuke Yonetoku , et al. · 2024

A wide-field X-ray survey in the soft X-ray band is crucial for future satellite missions in the astronomical observations. HiZ-GUNDAM, currently under development, is a proposed satellite designed to observe soft X-ray transients includin…

The Calorimetric Electron Telescope (CALET) on the International Space Station: Results from the first eight years on orbit Open

Yosui Akaike, O. Adriani, Katsuaki Asano, Y. Asaoka, E. Berti , et al. · 2024

The Calorimetric Electron Telescope, CALET, is an astroparticle physics mission installed on the International Space Station, ISS. The primary objective of the mission is studying the details of galactic cosmic-ray acceleration and propaga…

Possible X-ray Cocoon Emission from GRB 050709 Open

Naoki Ogino, M. Arimoto, Hamid Hamidani, T. Sakamoto, Daisuke Yonetoku , et al. · 2024

The detection of the short gamma-ray burst (SGRB) 050709 by the HETE-2 satellite opened a new window into understanding the nature of SGRBs, offering clues about their emission mechanism and progenitors, with the crucial aid of optical fol…

Direct measurements of cosmic – Ray iron and nickel with CALET on the International Space Station Open

O. Adriani, Yosui Akaike, Katsuaki Asano, Y. Asaoka, E. Berti , et al. · 2024

Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient Open

S. R. Oates, N. P. M. Kuin, M. Nicholl, F. E. Marshall, E. J. Ridley , et al. · 2024

We report the discovery of Swift J221951−484240 (hereafter: J221951), a luminous slow-evolving blue transient that was detected by the Neil Gehrels Swift Observatory Ultraviolet/Optical Telescope (Swift/UVOT) during the follow-up of gravit…

High-speed readout system of X-ray CMOS image sensor for time domain astronomy Open

Naoki Ogino, M. Arimoto, Tatsuya Sawano, Daisuke Yonetoku, Hsien-Chieh Shen , et al. · 2024

We developed an FPGA-based high-speed readout system for a complementary metal-oxide-semiconductor (CMOS) image sensor to observe soft X-ray transients in future satellite missions, such as HiZ-GUNDAM . Our previous research revealed that …

EXTRAORDINARY LUMINOUS SOFT X-RAY TRANSIENT MAXI J0158–744 AS AN IGNITION OF A NOVA ON A VERY MASSIVE O-Ne WHITE DWARF Open

M. Morii, H. Tomida, Minoru Kimura, F. Suwa, H. Negoro , et al. · 2024

We present the observation of an extraordinary luminous soft X-ray transient, MAXI J0158-744, by the Monitor of All-sky X-ray Image (MAXI) on 2011 November 11. This transient is characterized by a soft X-ray spectrum, a short duration (1.3…

Direct Measurement of the Spectral Structure of Cosmic-Ray in the TeV Region with CALET on the International Space Station Open

O. Adriani, Yosui Akaike, Katsuaki Asano, Y. Asaoka, E. Berti , et al. · 2023

Detailed measurements of the spectral structure of cosmic-ray electrons and positrons from 10.6 GeV to 7.5 TeV are presented from over 7 years of observations with the CALorimetric Electron Telescope (CALET) on the International Space Stat…

GRB 080710: A narrow, structured jet showing a late, achromatic peak in the optical and infrared afterglow? Open

Kaori Obayashi, Ayumu Toriyama, M. Murakoshi, Yuri Sato, Shuta Tanaka , et al. · 2023

We present a possible theoretical interpretation of the observed afterglow emission of long gamma-ray burst GRB 080710. While its prompt GRB emission properties are normal, the afterglow light curves in the optical and infrared bands are e…

Direct measurements of cosmic rays with the calorimetric electron telescope on the international space station Open

Yosui Akaike, O. Adriani, Katsuaki Asano, Y. Asaoka, E. Berti , et al. · 2023

The CALorimetric Electron Telescope, CALET, has been measuring high-energy cosmic rays on the International Space Station since October 13, 2015. The scientific objectives addressed by the mission are to search for possible nearby sources …

Results from CALorimetric Electron Telescope (CALET) Observations of Gamma-rays on the International Space Station Open

M. Mori, O. Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka , et al. · 2023

The CALorimetric Electron Telescope (CALET) cosmic ray detector on the International Space Station (ISS) has been in operation since its launch in 2015. The main instrument, the CALorimeter (CAL), is optimized to observe high-energy electr…

Optimizing Selection Criteria for the CALET Ultra-Heavy Cosmic Ray Analysis Open

Wolfgang V Zober, B. F. Rauch, Anthony W. Ficklin, N. Cannady, O. Adriani , et al. · 2023

CALET, the Calorimetric Electron Telescope, launched to the International Space Station in August 2015 and in continuous operation since, has gathered over seven years of data so far. CALET is able to measure cosmic-ray (CR) electrons, nuc…

Iron and Nickel fluxes measured by CALET on the International Space Station Open

F. Stolzi, O. Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka , et al. · 2023

propagation and acceleration phenomena in our Galaxy. The CALorimetric Electron Telescope (CALET) is measuring the spectra of heavy nuclei up to the highest directly observed energies on the International Space Station. In this contributio…

Dark Matter Limits from the CALET Electron+Positron Spectrum with Individual Astrophysical Source Background Open

Holger Motz, O. Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka , et al. · 2023

The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum of electron+positron cosmic rays up to 20 TeV. Annihilation or decay of dark matter (DM) could produce signatures in the positron and electron …

Feasibility study on an analysis of CR helium flux with the CALET detector based on an extended acceptance Open

M. Mattiazzi, O. Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka , et al. · 2023

In this work, we present a feasibility study aiming at a measurement of the cosmic ray (CR) helium flux utilizing CALET data with a significantly enhanced statistical precision. It is based on\na wider geometrical acceptance compared to th…

The cosmic-ray electron and positron spectrum measured with CALET on the International Space Station Open

Yosui Akaike, O. Adriani, Katsuaki Asano, Yoichi Aaoka, E. Berti , et al. · 2023

The CALorimetric Electron Telescope (CALET) has been collecting data on the International Space Station for more than seven years since October 2015. CALET is an all-calorimetric instrument with a total vertical thickness of 30 radiation l…

Cosmic-Ray Modulation during Solar Cycles 24-25 Transition Observed with CALET on the International Space Station Open

Shoko Miyake, O. Adriani, Katsuaki Asano, Yoichi Aaoka, E. Berti , et al. · 2023

We present the solar modulation of electrons and protons observed by the CALorimetric Electron Telescope onboard the International Space Station for about 7 years since October 2015, during the transition phase from the descending phase of…

Optimization of the proton background rejection in the measurement of the electron flux at high energies with CALET on the International Space Station Open

S. Gonzi, O. Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka , et al. · 2023

The Calorimetric Electron Telescope (CALET) is a cosmic-ray observatory operating since October 2015 onboard the International Space Station (ISS). The data processed since the beginning of the mission has made it possible to measure with …

Interpretation of the CALET Electron+Positron Spectrum by Astrophysical Sources Open

O. Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka, E. Berti , et al. · 2023

The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum of electron+positron cosmic rays up to 20 TeV. Supernova remnants (SNR) are the most likely astrophysical sources to provide the majority of th…

CALET Search for electromagnetic counterparts of gravitational waves in O4 Open

Y. Kawakubo, M. L. Cherry, T. Sakamoto, O. Adriani, Yosui Akaike , et al. · 2023

The latest LIGO/Virgo/KAGRA observing run (O4) started on May 24 in 2023. Many ground and space instruments have participated in follow-up observation and search for electromagnetic counterparts of gravitational waves. Calorimetric Electro…

Results of the Ultra-Heavy Cosmic-Ray Analysis with CALET on the International Space Station Open

Wolfgang V Zober, B. F. Rauch, O. Adriani, Yosui Akaike, Katsuaki Asano , et al. · 2023

The Calorimetric Electron Telescope (CALET), launched to the ISS in August 2015 and in continuous operation since, measures cosmic-ray (CR) electrons, nuclei, and gamma rays. CALET, with its 27 radiation length deep Total Absorption Calori…

Observation of spectral structures in the flux of cosmic ray protons with CALET on the International Space Station Open

Kazuyoshi Kobayashi, O. Adriani, Yosui Akaike, Katsuaki Asano, Yoichi Aaoka , et al. · 2023

A precise measurement of the cosmic-ray proton spectrum is carried out with the Calorimetric Electron Telescope (CALET) and a sharp softening of the energy spectrum above 10 TeV is observed. CALET, located on the International Space Statio…

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