Spectroscopic Follow-up Observation Report of PGIR21fjn/AT2021kgk (Perhaps a Classical Nova?)
ATel #14570; Kenta Taguchi, Keisuke Isogai, (Kyoto University), Kosuke Namekata (National Astronomical Observatory of Japan), Yusuke Tampo, Naoto Kojiguchi (Kyoto University)
on 22 Apr 2021; 16:22 UT
Credential Certification: Keisuke Isogai (isogai@kusastro.kyoto-u.ac.jp)
Subjects: Optical, Cataclysmic Variable, Nova, Transient, Variables
We report our spectrum of the highly reddened Galactic transient PGIR21fjn/AT2021kgk reported on ATel #14567.
We obtained the spectrum from 2021-03-20.72 UT to 2021-03-20.74 UT using the fiber-fed integral field spectrograph (KOOLS-IFU; Matsubayashi et al. 2019) mounted on the 3.8-m Seimei telescope (Kurita et al. 2020) at Okayama Observatory of Kyoto University.
Our observation was before ATel #14567 because we performed the observation soon after we noticed the discovery report posted to TNS.
Our spectrum is dominated by a highly reddened continuum with absorption features.
There is a possible P Cygni feature of Hα (see page 2 and 3 of the PDF), whose deep absorption has its minimum at ∼ 6533 Å and whose weak emission component has its maximum at ∼ 6561 Å (So, if the feature is truly a P Cygni profile, its speed will be ∼ 1,280 km/s, consistent with a classical nova outburst).
Also, probably emission lines are seen at 8545, 8598, 10049 Å (Paschen) and at 8227 Å (O I), however interstellar and/or telluric absorption feature is so strong nearby that we cannot judge whether they are truly emission lines.
To sum up, our spectrum and the amplitude of the outburst prefer that this object is a classical nova having the P Cygni profile of Hα.
However the optical light is so weak, so further observations (especially infrared spectroscopy) are strongly encouraged.
Our Spectrum