Spectroscopic and photometric identification of ASASSN-20kv = AT 2020saz as a dwarf nova.

ATel #13971; Kenta Taguchi, Naoto Kojiguchi, Yusuke Tampo, Soshi Okamoto, Kosuke Namekata, Keisuke Isogai (Kyoto University)
on 26 Aug 2020; 20:24 UT
Credential Certification: Keisuke Isogai (isogai@kusastro.kyoto-u.ac.jp)

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We report on a spectrum of the bright optical transient ASASSN-20kv = AT 2020saz. We obtained the spectrum on 2020-08-27.3 UT by using a fiber-fed integral field spectrograph (KOOLS-IFU; Matsubayashi et al. 2019) mounted on the 3.8-m telescope Seimei at Okayama Observatory of Kyoto University.

As reported to TNS, this object was discovered at 14.4 mag on 2020-8-26.67 UT by ASAS-SN (Shappee et al. 2014). It was also detected at r=14.7 at 2020-08-26.25 and g = 14.3 2020-08-26.32 by ZTF as ZTF20abwvhwm. There is a possible counterpart in the PS1 image but is no photometry data (the limiting magnitude is ~23).

Our spectrum shows a blue continuum with weak Balmer absorption lines. These features suggest that this object is a dwarf nova in outburst, not a classical nova.

We also performed multicolor photometry by using the Kyoto Univerisity 40-cm telescope on 2020-8-26.64 UT. The magnitudes were B=14.66, V=14.53, R=14.54, and I=14.55. The colors also support the result that the object is not a classical nova but a dwarf nova. The large outburst amplitude suggests a WZ Sge-type dwarf nova.

Spectrum