Spectroscopic confirmation of TCP J05384230+7051377 as a WZ Sge-type dwarf nova
ATel #17485; Hiromasa Hoke, Keisuke Isogai (Kyoto University), Yusuke Tampo (South African Astronomical Observatory, University of Cape Town)
on 8 Nov 2025; 11:24 UT
Credential Certification: Keisuke Isogai (isogai@kusastro.kyoto-u.ac.jp)
Subjects: Optical, Binary, Cataclysmic Variable, Transient, Variables
We report on spectral features in the transient TCP J05384230+7051377 on 2025-11-07.6332 UT obtained with a fiber-fed integral field spectrograph (KOOLS-IFU; Matsubayashi et al. 2019, 2025) attached to one of the Nasmyth focuses of the 3.8-m telescope Seimei at Okayama Observatory of Kyoto University. In short, we conclude that this object is a WZ Sge-type dwarf nova.
According to CBAT, the outburst of TCP J05384230+7051377 was discovered at CV=12.9 mag on 2025-11-07.0576 UT by the NMW survey. There is a likely counterpart in Pan-STARRS and GALEX, whose brightnesses are g=20.4, r=20.3, i=20.5, z=20.5, FUV=20.7, and NUV=21.1. The absolute magnitude is estimated to be Mg = 12.0+0.5-0.6 by the distance of Gaia EDR3 (Bailer-Jones et al. 2021). Gentile Fusillo et al. (2021) reported that this object is a white dwarf candidate based on Gaia's HR diagram. Judging from the outburst amplitude of ∼7.5mag, Mg, and its quiescent color, this object was expected to be a WZ Sge-type dwarf nova.
We obtained an optical spectrum on 2025-11-07.6332 UT. Our quick look spectrum shows a blue continuum with the Balmer and HeI absorption lines. Also, Hα has a narrow emission core. From these spectral features, we conclude that this object is a new bright WZ Sge-type dwarf nova.
Our spectrum
