AstroNote 2020-99

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 ZTF20aaynrrh / 2020jfo, following the methodology outlined by Gal-Yam et al. (2011).

The object was first detected on ZTF r-band images obtained on 6 May 2020 04:51 UT, about 3.9 days after the last non-detection, and was picked up by the Redshift Completeness Factor custom Marshal filter. The object was saved by a duty astronomer and rapid follow-up was triggered. The object was publicly announced by the AMPEL system (Nordin et al. 2019) via the TNS.

Assuming the redshift of the host (M61, z=0.005224 from NED), the SN was discovered around absolute magnitude Mr = -15.8.

Rapid spectroscopy with the SEDm (Blagoradnova, et al. 2018, PASP, v130, 035003) and the Liverpool telescope reveals a blue continuum that suggests a core-collapse supernova origin.

Swift photometry has been triggered by P.I.s Burke and Margutti. A first analysis of the Swift data reveals a bright transient that is brightening in the UV filters. 

The Swift X-ray telescope detected X-ray emission from the SN position. The count-rate is 0.0057 +0.0026 -0.0020 ct/s (0.3-10 keV). Assuming a power-law with a photon index of 2 and Galactic N(H,X) of 1.760e20 cm^2, the count-rate corresponds to a flux of ~2.1 erg/s/cm^2 (0.3-10 keV, corrected for absorption). Note, Swift recorded X-ray emission from the same position between 2008 and 2020 at a somewhat lower level. 

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