86 citations · 294 across the 23 of their papers we have counts for
23 papers
2021 superoutburst of WZ Sge-type dwarf nova V627 Pegasi lacks an early superhump phase
Yusuke Tampo, Taichi Kato, Naoto Kojiguchi +27
Superoutbursts in WZ Sge-type dwarf novae (DNe) are characterized by both early superhumps and ordinary superhumps originating from the 2:1 and 3:1 resonances, respectively. Howeve…
Analysis of the IW And star ASAS J071404+7004.3
Taichi Kato, Kiyoshi Kasai, Elena P. Pavlenko +14
We made a time-resolved photometric campaign of the bright cataclysmic variable ASAS J071404+7004.3 in 2020. Inight et al. (2022, arXiv/2109.14514) recently published time-resolved…
Orbital and spin periods of the candidate white dwarf pulsar ASASSN-V J205543.90+240033.5
Taichi Kato, Franz-Josef Hambsch, Elena P. Pavlenko +1
ASASSN-V J205543.90+240033.5 has been suggested to be a white dwarf pulsar by Kato (2021, arXiv:2108.09060). We obtained time-resolved photometry and identified the orbital and spi…
Optical Variability Correlated with X-ray Spectral Transition in the Black-Hole Transient ASASSN-18ey = MAXI J1820+070
Keito Niijima, Mariko Kimura, Yasuyuki Wakamatsu +49
How a black hole accretes matter and how this process is regulated are fundamental but unsolved questions in astrophysics. In transient black-hole binaries, a lot of mass stored in…
On the nature of the anomalous event in 2021 in the dwarf nova SS Cygni and its multi-wavelength transition
Mariko Kimura, Shinya Yamada, Nozomi Nakaniwa +20
SS Cyg has long been recognized as the prototype of a group of dwarf novae that show only outbursts. However, this object has entered a quite anomalous event in 2021, which at firs…
BO Ceti: Dwarf Nova Showing Both IW And and SU UMa-Type Features
Taichi Kato, Yusuke Tampo, Naoto Kojiguchi +13
IW And stars are a recently recognized subgroup of dwarf novae which are characterized by (often repetitive) slowly rising standstills terminated by brightening, but the exact mech…
Spectroscopic and Photometric Observations of Dwarf Nova Superoutbursts by the 3.8 m Telescope Seimei and the Variable Star Network
Yusuke Tampo, Keisuke Isogai, Naoto Kojiguchi +59
We present spectroscopic and photometric observations of 17 dwarf-nova superoutbursts obtained by KOOLS-IFU mounted on the 3.8 m telescope Seimei at Okayama Observatory of Kyoto Un…
Multi-wavelength photometry during the 2018 superoutburst of the WZ Sge-type dwarf nova EG Cancri
Mariko Kimura, Keisuke Isogai, Taichi Kato +45
We report on the multi-wavelength photometry of the 2018 superoutburst in EG Cnc. We have detected stage A superhumps and long-lasting late-stage superhumps via the optical photome…
ASASSN-18fk: A new WZ Sge-type dwarf nova with multiple rebrightenings and a new candidate for a superhumping intermediate polar
E. Pavlenko, K. Niijima, P. Mason +23
We present the result of a multi-longitude campaign on the photometric study of the dwarf nova ASASSN-18fk during its superoutburst in 2018. It was observed with 18 telescopes at 1…
Discovery of Standstills in the SU UMa-Type Dwarf Nova NY Serpentis
Taichi Kato, Elena P. Pavlenko, Nikolaj V. Pit +40
We found that the SU UMa-type dwarf nova NY Ser in the period gap [orbital period 0.097558(6) d] showed standstills twice in 2018. This is the first clear demonstration of a stands…
Long-period SU UMa dwarf nova V1006 Cygni outburst activity and variability at different brightness states in 2015-2017
E. P. Pavlenko, S. Yu. Shugarov, A. O. Simon +11
CCD photometric observations of the dwarf nova V1006 Cyg were carried out in 2015-2017 with 11 telescopes located at 7 observatories. They covered the 2015 superoutburst with rebri…
Asynchronous polar V1500 Cyg: orbital, spin and beat periods
E. P. Pavlenko, P. A. Mason, A. A. Sosnovskij +7
The bright Nova Cygni 1975 is a rare nova on a magnetic white dwarf (WD). Later it was found to be an asynchronous polar, now called V1500 Cyg. Our multisite photometric campaign o…
On the Nature of Long-Period Dwarf Novae with Rare and Low-Amplitude Outbursts
Mariko Kimura, Taichi Kato, Hiroyuki Maehara +35
There are several peculiar long-period dwarf-nova like objects, which show rare, low-amplitude outbursts with highly ionized emission lines. 1SWASP J162117441254, BD Pav, and V3…
NY Her: possible discovery of negative superhumps
A. Sosnovskij, E. Pavlenko, N. Pit +1
We presents result of CDD photometry for SU UMa dwarf nova NY Her during 6 nights in June 2017 when object was in quiescence. Light curves clearly show strong amplitude variations…
Rapid Optical Variations Correlated with X-rays in the 2015 Second Outburst of V404 Cygni (GS 2023338)
Mariko Kimura, Taichi Kato, Keisuke Isogai +24
We present optical multi-colour photometry of V404 Cyg during the outburst from December, 2015 to January, 2016 together with the simultaneous X-ray data. This outburst occurred le…
Superoutburst of WZ Sge-type Dwarf Nova Below the Period Minimum: ASASSN-15po
Kosuke Namekata, Keisuke Isogai, Taichi Kato +38
We report on a superoutburst of a WZ Sge-type dwarf nova (DN), ASASSN-15po. The light curve showed the main superoutburst and multiple rebrightenings. In this outburst, we observed…
Repetitive Patterns in Rapid Optical Variations in the Nearby Black-hole Binary V404 Cygni
Mariko Kimura, Keisuke Isogai, Taichi Kato +65
How black holes accrete surrounding matter is a fundamental, yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion…
Superoutburst of CR Bootis: Estimation of Mass Ratio of a typical AM CVn star by Stage A Superhumps
Keisuke Isogai, Taichi Kato, Tomohito Ohshima +31
We report on two superoutbursts of the AM CVn-type object CR Boo in 2014 April--March and 2015 May--June. A precursor outburst acompanied both of these superoutbursts. During the r…
V1006 Cygni: Dwarf Nova Showing Three Types of Outbursts and Simulating Some Features of the WZ Sge-Type Behavior
Taichi Kato, Elena P. Pavlenko, Alisa V. Shchurova +17
We observed the 2015 July-August long outburst of V1006 Cyg and established this object to be an SU UMa-type dwarf nova in the period gap. Our observations have confirmed that V100…
Unexpected Superoutburst and Rebrightening of AL Comae Berenices in 2015
Mariko Kimura, Taichi Kato, Akira Imada +10
In 2015 March, the notable WZ Sge-type dwarf nova AL Com exhibited an unusual outburst with a recurrence time of 1.5 yr, which is the shortest interval of superoutbursts am…
Dwarf Nova EZ Lyncis Second Visit to Instability Strip
Elena Pavlenko, Taichi Kato, Aleksei A. Sosnovskij +5
The analysis of 14 periodograms of EZ Lyn for the data spaced over 565 d in 2012--2014 (2-3.5 yr after 2010 outburst) yielded the existence of the stable signals around 100 c/d and…
NY Serpentis: SU UMa-Type Nova in the Period Gap with Diversity of Normal Outbursts
Elena P. Pavlenko, Taichi Kato, Oksana I. Antonyuk +16
We present photometric study of NY Ser, an in-the-gap SU UMa-type nova, in 2002 and 2013. We determined the duration of the superoutburst and the mean superhump period to be 18 d a…
Superoutburst of SDSS J090221.35+381941.9: First Measurement of Mass Ratio in an AM CVn-Type Object using Growing Superhumps
Taichi Kato, Tomohito Ohshima, Denis Denisenko +36
We report on a superoutburst of the AM CVn-type object SDSS J090221.35+381941.9 [J0902; orbital period 0.03355(6) d] in 2014 March-April. The entire outburst consisted of a precurs…