AstroNote 2021-171

The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841), in the framework of the ASYAGO Program (Asiago School for Young Astronomers with Galileo Observations, tutors: Costantino Sigismondi, Virginio Oldani, Federico Manzini), reports the spectroscopic classification of AT2021pin.

The discovery report was supplied by MASTER (Mobile Astronomical System of Telescope-Robots, Lipunov et al. 2004).

The observation was performed with the Asiago 1.22m Galileo Telescope (+B&C 300tr; range 330-790 nm; resolution 0.7 nm).

The spectrum is similar to that of a Dwarf Nova in outburst, with a blue continuum and relatively broad (FWHM~2,500 km/s) Balmer lines in absorption. The Hbeta line is less prominent than Hgamma, and Halpha is not visible, probably filled by the emission from the accretion disk.

The transient is associated to the known SU UMa-Type Cataclysmic Variable V362 Lib (Vogt et al. 2021, Kato et al. 2013, Woudt et al. 2012), that during this outburst experienced a brightening by almost 6 magnitudes, from r=19.9 mag (from the Pan-STARRS1 catalog) to CR=14.2 mag.