Spectroscopic classification of ASASSN-21fh as a classical nova of the Fe II class

ATel #14544; Vishal Joshi, Sandipan Borthakur, Dipankar P K Banerjee, Mudit K. Srivastava (Physical Research Laboratory, Ahmedabad, India)
on 13 Apr 2021; 01:36 UT
Credential Certification: Vishal Joshi (vjoshi@prl.res.in)

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We report optical spectroscopy of ASASSN-21fh, suspected to be a Possible Galactic Nova in Scorpius. The transient was discovered at mag 11.1 by the All-Sky Automated Survey for Supernovae (ASAS-SN) on 2021 04 12.168 UT and reported by Patrick Schmeer in VSNET-Alert 25711 (https://www.aavso.org/vsx/index.php?view=detail.top&oid=2217653). ASAS-SN g mag was 10.4 on 2021 04 12.407 UT. We obtained optical spectra of ASASSN-21fh on 2021 04 12.916 UT using the Mt. Abu Faint Object Spectrograph and Camera - Pathfinder (MFOSC-P) on the PRL 1.2m Telescope at Mt. Abu observatory. The observations were acquired in partially cloudy conditions. The spectra were recorded in two modes; low-resolution mode with R ~ 500 covering the 4400-9000 AA in two settings of the grating and an R ~ 2000 mode covering ~ 6100-7100 AA. The spectrum shows a red continuum with P Cygni profiles of H-Balmer, Fe II, and O I lines. The emission components of most of the P Cygni profiles are weak relative to the continuum except H alpha and H beta lines. The FWHM and FWZI of the H-alpha emission component are ~ 2380 and 3800, respectively derived from R 2000 spectrum. The absorption troughs of P Cygni blue shifted by ~ 2200, 1665, and 1620 km/s relative to the rest velocities for H alpha, H beta, and OI 7773A lines, respectively (profiles not deconvolved for instrumental broadening). On the basis of large outburst amplitude (> 6.5 mag) and H-Balmer and Fe II lines with P Cygni feature, we classify the transient to be a classical nova of the Fe II class caught early in its outburst.