AstroNote 2020-253

Here we report on a classification spectrum for AT2020acli (DLT20aa), a faint transient (r=18.5 mag; M_r=-8.0 mag) discovered in NGC300 by the DLT40 survey.  A Gemini-S GMOS spectrum was taken on 2020-12-12T15:41:46, approximately 24 hours after discovery using a rapid ToO trigger (PI Lundquist).  The spectrum showed strong hydrogen balmer emission, with a P Cygni absorption feature at  -4000 km/s. Using the classification software GELATO  (Harutyunyan et al. 2008 2008A&A...488..383H), the best-fitting template corresponds to the peculiar type IIn SN2009ip during the phase prior to its giant eruption. There is very little reddening towards AT2020acli, yet the absolute magnitude is several magnitudes fainter than SN 2009ip in a similar phase. Some similarity is also found with low luminosity type II SNe (e.g. SN1999br, Pastorello et al. 2004 2004MNRAS.347...74P), but AT2020acli is also in this case several magnitudes fainter than low luminosity SNe IIP.  Further follow-up observations are encouraged.