A radio transient associated with SN 2019xhb discovered in Epoch 2 of the VLA Sky Survey (VLASS)
ATel #14020; Gregg Hallinan (Caltech), Kunal Mooley (NRAO, Caltech), Dillon Dong, Vikram Ravi, Casey Law (Caltech), Steve Myers (NRAO), Gregory R. Sivakoff, Falon Scheers (U Alberta), Aryanna Schiebelbein (U Alberta, U Waterloo), Shami Chatterjee (Cornell), Tracy Clarke (NRL), Peter Eisenhardt, Dan Stern (JPL), Hyunsung Jun (KIAS), Tanio Diaz-Santos (Crete)
on 16 Sep 2020; 23:57 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Kunal Mooley (kmooley@caltech.edu)
Subjects: Radio, Optical, Supernovae, Transient
A near-real-time transient search in the first 1000 sq. degrees of the second epoch of the VLA Sky Survey (VLASS; Lacy et al. 2020) has produced a number of transient candidates absent from the reference epoch observed 32 months earlier. In this sample, VLASS2 J001010.69-060003.5 (1.4+/-0.2 mJy), was confirmed to be associated with SN 2019xhb/ZTF19adaxza, optically classified as an ordinary Type II supernova at 130 Mpc (Forster et al. 2019). On 2020 August 25, we carried out optical spectroscopy with the Double Spectrograph (DBSP) on the Palomar 200-inch Hale telescope. These spectroscopic data place the supernova at a much closer distance of 60 Mpc, consistent with a luminosity of 6e27 erg/s/Hz at 3 GHz for the radio transient on 2020 July 10, and also revealed that the supernova has late-time broad optical features consistent with a Type Ib/c.
VLASS is a synoptic radio survey of 34,000 square degrees carried out at S band (2-4 GHz) across 3 epochs over 7 years with the Karl G. Jansky Very Large Array. The second epoch commenced recently (July 2020), presenting the opportunity to identify radio transients with a reference epoch of equivalent depth, resolution, frequency and sky coverage. To enable transient studies, NRAO provides Quick Look images after initial calibrations and simple synthesis imaging reduction. The Canadian Initiative for Radio Astronomy Data Analysis (CIRADA) has made a simple cutout service (cutouts.cirada.ca) that provides easy public access to cutouts of the images supplied by NRAO, as well as some selected other multiwavelength surveys.
We express our gratitude towards the NRAO staff who have made the VLASS possible and to the VLASS Survey Science Group (SSG). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. CIRADA is funded by a grant from the Canada Foundation for Innovation 2017 Innovation Fund (Project 35999), as well as by the Provinces of Ontario, British Columbia, Alberta, Manitoba and Quebec, in collaboration with the National Research Council of Canada, the US National Radio Astronomy Observatory and Australia's Commonwealth Scientific and Industrial Research Organisation.
References:
(1) Lacy et al. 2020, PASP, 132, 5001
(2) Forster et al. 2019, TNS Report No. 55262
(3) VLASS website: https://science.nrao.edu/vlass
