AstroNote 2019-131

The Zwicky Transient Facility (ZTF; Bellm et al. 2019; Graham et al. 2019) Infant Supernova Science Program (Gal-Yam 2019) reports the early discovery and rapid follow-up of AT2019ust (ZTF19acryurj), following the methodology outlined by Gal-Yam et al. (2011). The object was first detected on ZTF r-band images obtained on 13 November 2019 at 06:57 UTC, about 23.6 hours after the last non-detection, and was picked up by the infant supernova custom Marshal filter. The object was saved by a duty astronomer and rapid follow-up was triggered. A spectrum obtained with GMOS at Gemini-North on 14 November 2019 at 11:47 UT showed narrow emission lines of ionised species (HeII, CIV, NIII, Balmer lines) on top of a blue continuum, consistent with a very young and hot transient event. 

The redshift of the apparent host (UGC 548) is z = 0.022 (~99 Mpc) based on the NASA Extragalactic Database (http://ned.ipac.caltech.edu/). The transient was hence discovered around r = -15.6 absolute magnitude. Swift photometry, high cadence spectroscopy and radio observations have been requested.  Additional observations are ongoing. 

We will continue to distribute alerts on such early SN detections via AstroNotes; additional follow-up observations of this event are encouraged.

ZTF is a project led by PI S. R. Kulkarni at Caltech, and includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA; UW,USA; DESY, Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. Alert distribution service provided by DIRAC@UW. Alert filtering is being undertaken by the GROWTH marshal system (Kasliwal et al. 2019), supported by NSF PIRE grant 1545949.