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SN 2023gfo: A Peculiar Type IIP Supernova with High Luminosity and Normal Plateau Duration
Riko Namba, Masayuki Yamanaka, Keiichi Maeda +9
We present near-infrared (NIR) and optical observations of the highly reddened Type IIP supernova (SN) 2023gfo in the nearby galaxy NGC 4995 ( Mpc), which reached…
JWST Spectroscopy of Type Ia Supernova 2025rbs from Maximum Light to the Nebular Phase
Lindsey A. Kwok, Stéphane Blondin, Adam A. Miller +53
We present JWST observations of the Type Ia supernova (SN Ia) 2025rbs (14.5 Mpc) at +1, +23, and +84 days after B-band maximum, spanning peak light through a wavelength-depende…
SN 2023xgo: Helium-rich Type Icn or Carbon-Flash Type Ibn supernova?
Anjasha Gangopadhyay, Jesper Sollerman, Konstantinos Tsalapatas +35
We present observations of SN~2023xgo, a transitional Type Ibn/Icn supernova, from to ~days relative to the -band peak. Early spectra show C~III emission rem…
SN 2023vbg: A Type IIn Supernova Resembling SN 2009ip, with a Long-Duration Precursor and Early-Time Bump
Sota Goto, Masayuki Yamanaka, Takahiro Nagayama +9
Type IIn supernovae (SNe) resembling SN 2009ip (09ip-like SNe) originate from the interaction between circumstellar material (CSM) and the ejecta. This subclass not only shares sim…
Spectropolarimetry of A Nuclear Transient AT2023clx: Revealing The Geometrical Alignment between The Transient Outflow and The Nuclear Dusty Region
Kohki Uno, Keiichi Maeda, Takashi Nagao +10
AT2023clx, which occurred in NGC3799 with a Low-Ionization Nuclear Emission-Line Region (LINER), is one of the most nearby nuclear transients classified as a tidal disruption event…
SN 2021foa: the bridge between SN IIn and Ibn
Anjasha Gangopadhyay, Naveen Dukiya, Takashi J Moriya +26
We present the long-term photometric and spectroscopic analysis of a transitioning SN~IIn/Ibn from 10.8 d to 150.7 d post -band maximum. SN~2021foa shows prominent He {\sc i}…
Unravelling the asphericities in the explosion and multi-faceted circumstellar matter of SN 2023ixf
Avinash Singh, R. S. Teja, T. J. Moriya +33
We present a detailed investigation of photometric, spectroscopic, and polarimetric observations of the Type II SN 2023ixf. Earlier studies have provided compelling evidence for a…
Intermediate-luminosity Type IIP SN 2021gmj: a low-energy explosion with signatures of circumstellar material
Yuta Murai, Masaomi Tanaka, Miho Kawabata +28
We present photometric, spectroscopic and polarimetric observations of the intermediate-luminosity Type IIP supernova (SN) 2021gmj from 1 to 386 days after the explosion. The peak…
The enigmatic double-peaked stripped-envelope SN 2023aew
Tuomas Kangas, Hanindyo Kuncarayakti, Takashi Nagao +29
We present optical and near-infrared photometry and spectroscopy of SN 2023aew and our findings on its remarkable properties. This event, initially resembling a Type IIb supernova…
Gamma rays from a reverse shock with turbulent magnetic fields in GRB 180720B
Makoto Arimoto, Katsuaki Asano, Koji S. Kawabata +14
Gamma-ray bursts (GRBs) are the most electromagnetically luminous cosmic explosions. They are powered by collimated streams of plasma (jets) ejected by a newborn stellar-mass black…
Bridging between type IIb and Ib supernovae: SN IIb 2022crv with a very thin Hydrogen envelope
Anjasha Gangopadhyay, Keiichi Maeda, Avinash Singh +26
We present optical, near-infrared, and radio observations of supernova (SN) SN~IIb 2022crv. We show that it retained a very thin H envelope and transitioned from a SN~IIb to a SN~I…
Systematic Investigation of Very Early-Phase Spectra of Type Ia Supernovae
Mao Ogawa, Keiichi Maeda, Miho Kawabata
It has been widely accepted that Type Ia supernovae (SNe Ia) are thermonuclear explosions of a CO white dwarf. However, the natures of the progenitor system(s) and explosion mechan…
SN 2018gj: A Short-plateau Type II Supernova with Persistent Blue-shifted H-alpha Emission
Rishabh Singh Teja, Avinash Singh, D. K. Sahu +7
We present an extensive, panchromatic photometric (UV, Optical, and NIR) and low-resolution optical spectroscopic coverage of a Type IIP supernova SN 2018gj that occurred on the ou…
Initial Flash and Spectral Formation of Type Ia Supernovae with An Envelope: Applications to Over-luminous SNe Ia
Keiichi Maeda, Ji-an Jiang, Mamoru Doi +2
Over-luminous type Ia supernovae (SNe Ia) show peculiar observational features, for which an explosion of a super-massive white dwarf (WD) beyond the classical Chandrasekhar-limiti…
SN 2020uem: A Possible Thermonuclear Explosion within A Dense Circumstellar Medium (II) The Properties of The CSM from Polarimetry and Light Curve Modeling
Kohki Uno, Takashi Nagao, Keiichi Maeda +11
Type IIn/Ia-CSM supernovae (SNe IIn/Ia-CSM) are classified by their characteristic spectra, which exhibit narrow hydrogen emission lines originating from a strong interaction with…
SN 2020uem: A Possible Thermonuclear Explosion within A Dense Circumstellar Medium (I) The Nature of Type IIn/Ia-CSM SNe from Photometry and Spectroscopy
Kohki Uno, Keiichi Maeda, Takashi Nagao +18
We have performed intensive follow-up observations of a Type IIn/Ia-CSM SN (SN IIn/Ia-CSM), 2020uem, with photometry, spectroscopy, and polarimetry. In this paper, we report on the…
Properties of Type Iax Supernova 2019muj in the Late Phase: Existence, Nature and Origin of the Iron-rich Dense Core
Keiichi Maeda, Miho Kawabata
Type Iax Supernovae (SNe Iax) form a class of peculiar SNe Ia, whose early-phase spectra share main spectral line identifications with canonical SNe Ia but with higher ionization a…
Discovery of the Fastest Early Optical Emission from Overluminous SN Ia 2020hvf: A Thermonuclear Explosion within a Dense Circumstellar Environment
Ji-an Jiang, Keiichi Maeda, Miho Kawabata +28
In this Letter we report a discovery of a prominent flash of a peculiar overluminous Type Ia supernova, SN 2020hvf, in about 5 hours of the supernova explosion by the first wide-fi…
Intermediate Luminosity Type Iax SN 2019muj With Narrow Absorption Lines: Long-Lasting Radiation Associated With a Possible Bound Remnant Predicted by the Weak Deflagration Model
Miho Kawabata, Keiichi Maeda, Masayuki Yamanaka +23
We present comprehensive spectroscopic and photometric analyses of the intermediate luminosity Type Iax supernova (SN Iax) 2019muj based on multi-band datasets observed through the…
Light curve properties of SN 2017fgc and HV SNe Ia
Umut Burgaz, Keiichi Maeda, Belinda Kalomeni +5
Photometric and spectroscopic observations of type Ia supernova (SN) 2017fgc which cover the period from 12 to +137 days since the -band maximum are presented. SN 2017fgc is…
Follow-up Observations for IceCube-170922A: Detection of Rapid Near-Infrared Variability and Intensive Monitoring of TXS 0506+056
Tomoki Morokuma, Yousuke Utsumi, Kouji Ohta +35
We present our follow-up observations to search for an electromagnetic counterpart of the IceCube high-energy neutrino, IceCube-170922A. Monitoring observations of a likely counter…
Calcium-rich Transient SN 2019ehk in A Star-Forming Environment: Yet Another Candidate for An Ultra-Stripped Envelope Supernova
Tatsuya Nakaoka, Keiichi Maeda, Masayuki Yamanaka +20
We present optical and near-infrared observations of SN~Ib~2019ehk. We show that it evolved to a Ca-rich transient according to its spectral properties and evolution in late phases…
Multiband optical flux density and polarization microvariability study of optically bright blazars
Magdalena Pasierb, Arti Goyal, Michał Ostrowski +21
We present the results of flux density, spectral index, and polarization intra-night monitoring studies of a sample of eight optically bright blazars, carried out by employing seve…
SN 2018hna: 1987A-like supernova with a signature of shock breakout
Avinash Singh, D. K. Sahu, G. C. Anupama +22
High cadence ultraviolet, optical and near-infrared photometric and low-resolution spectroscopic observations of the peculiar Type II supernova (SN) 2018hna are presented. The earl…