AstroNote 2023-335

We report the discovery of ZTF23absbqun / AT 2023zaw - a fast-fading, subluminous and red transient in the galaxy UGC 03048 at a distance of ~45 Mpc. 

ZTF23absqbun was first detected by the regular ZTF survey on MJD 60285.2320 in the g-band at m_g = 19.34 +/- 0.15 mag. In the next two days, it brightened to its peak m_g = 18.85 +/- 0.08 on MJD 60287.2823. After correcting for Galactic extinction in the direction of the transient of E(B-V) = 0.25 mag (Schlafly & Finkbeiner, 2011), this corresponds to a peak absolute magnitude Mg_abs ~ -15.2 mag. The extinction-corrected color at peak is g - r ~ 0.4 mag.

Since then, the transient has been fading rapidly at a rate of 0.4 +/- 0.1 mag/day in the g-band. It was automatically flagged as a fast transient candidate by the ZTFReST framework for kilonova and fast transient discovery (Andreoni & Coughlin et al., 2021). 

We obtained a spectrum with the ALFOSC spectrograph on the Nordic Optical Telescope on 2023-12-09 UT, which confirmed the association with UGC 03048 at a redshift of z=0.0101 (based on narrow H-alpha and [SII] galaxy emission lines). Additionally, the spectrum showed several broad features, but cross-matches to supernova templates using SNID (Blondin & Tonry 2007) and NGSF (AstroNote 2022-191, Howell et al. 2005) did not yield any convincing matches.  

Further follow-up observations are strongly encouraged.

Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Oskar Klein Center at Stockholm University, the University of Maryland, University of California, Berkeley , the University of Wisconsin at Milwaukee, University of Warwick, Ruhr University, Cornell University, Northwestern University and Drexel University. Operations are conducted by COO, IPAC, and UW.