AstroNote 2019-22

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 SN 2019gmh (ZTF19aawgxdn), following the methodology outlined by Gal-Yam et al. (2011). The object was first detected on ZTF r-band images obtained on June 1, 2019 at 05:17 UT, about 45 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. The object also passed the Redshift Completeness Factor (RCF) filter and was publicly announced by the AMPEL system (Nordin et al. 2019) via the TNS. A spectrum obtained with the SEDM instrument (Blagorodnova et al. 2018) mounted on the robotic P60 1.5m telescope at Palomar Observatory on 10:25 UT showed a blue continuum with a low-contrast broad Halpha line and weaker features consistent with higher Balmer lines, suggesting this is a very young Type II supernova. Observations are available via the TNS. Assuming the redshift of the apparent host (UGC 10436, z=0.030234; d=130 Mpc from NED), the SN was discovered around g=-17 absolute magnitude. Swift photometry has been triggered and additional observations are ongoing.

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