86 citations · 245 across the 13 of their papers we have counts for
14 papers
Multi-band optical photometric variability of the blazar OJ 287 from 2015 to 2025
Alok C. Gupta, Karan Dogra, Mark Kidger +101
We present the most densely sampled multi-band optical photometric observations of the peculiar BL Lacertae object OJ 287 from 2015 to 2025 with a focus on its optical activity on…
Rapid X-ray Variability in Mkn 421 during a Multiwavelength Campaign
Alex G. Markowitz, Krzysztof Nalewajko, Gopal Bhatta +47
The study of short-term variability properties in AGN jets has the potential to shed light on their particle acceleration and emission mechanisms. We report results from a four-day…
ASASSN-18aan: An Eclipsing SU UMa-type Cataclysmic Variable with a 3.6-hour Orbital Period and a Late G-type Secondary Star
Yasuyuki Wakamatsu, John R. Thorstensen, Naoto Kojiguchi +41
We report photometric and spectroscopic observations of the eclipsing SU UMa-type dwarf nova ASASSN-18aan. We observed the 2018 superoutburst with 2.3 mag brightening and found the…
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…
IW And-Type State in IM Eridani
Taichi Kato, Yasuyuki Wakamatsu, Naoto Kojiguchi +20
IW And stars are a recently recognized group of dwarf novae which are characterized by a repeated sequence of brightening from a standstill-like phase with damping oscillations fol…
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…
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…
Breaking the habit - the peculiar 2016 eruption of the unique recurrent nova M31N 2008-12a
M. Henze, M. J. Darnley, S. C. Williams +70
Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with…
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…
RZ Leonis Minoris Bridging between ER Ursae Majoris-Type Dwarf Nova and Novalike System
Taichi Kato, Ryoko Ishioka, Keisuke Isogai +64
We observed RZ LMi, which is renowned for the extremely (~19d) short supercycle and is a member of a small, unusual class of cataclysmic variables called ER UMa-type dwarf novae, i…
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…
ASASSN-15jd: WZ Sge-type star with intermediate superoutburst between single and double ones
Mariko Kimura, Keisuke Isogai, Taichi Kato +21
We present optical photometry of a WZ Sge-type dwarf nova (DN), ASASSN-15jd. Its light curve showed a small dip in the middle of the superoutburst in 2015 for the first time among…