AstroNote 2019-30

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 AT2019hgp (ZTF19aayejww), following the methodology outlined by Gal-Yam et al. (2011). The object was first detected on ZTF r-band images obtained on June 8, 2019 at 5:48 UT, about 22 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 the SEDM instrument (Blagorodnova et al. 2018) mounted on the robotic P60 1.5m telescope at Palomar Observatory on 10:18 UT showed narrow emission lines of highly ionised species (OIII, CIII) on top of blue continuum, consistent with a very young and hot transient event. 

The redshift of the apparent host (SDSS J153613.02+394357.5) was estimated at z = 0.064 (~280Mpc) based on the analysis of a host spectrum from Gemini. The transient was hence discovered around r = -17 absolute magnitude. Swift photometry and high cadence spectroscopy have been requested.  Additional observations are ongoing. 

Observations are available via the TNS. 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.