X-ray and UV detections of the supernova candidate ASASSN 16fp (AT 2016coi) with Swift
ATel #9088; Dirk Grupe (Morehead State University), Peter Brown (Texas A&M), Subo Dong (KIAA-PKU), B. J. Shappee (Carnegie Observatories), Tom Holoien, Kris Stanek (Ohio State University), Jose L. Prieto (Universidad Diego Portales), & Raffaella Margutti (New York University)
on 28 May 2016; 02:12 UT
Credential Certification: Dirk Grupe (dgrupe007@gmail.com)
Subjects: Optical, Ultra-Violet, X-ray, Supernovae
We report on the discovery of X-rays at a position consistent with the newly discovered supernova candidate ASAS-SN 16fp (AT 2016coi; ATEL 9086, Holoien et al.) with Swift. The field of this source was observed 2016-05-27 17:00 - 19:59 UT for a total of 1913s. We found an X-ray source at RA-2000=21 59 04.21, Dec-2000=+18 11 11.8 with an 90% confidence radius of 5.7". This position is 1.6" away from the optical position reported in ATEL 9086.
The source is tentatively detected at a 3sigma level of (2.48+1.33/-1.00)e-3 counts/s (uncertainties determined by the method described by Kraft et al. 1991, ApJ 374, 344), which corresponds to an observed flux in the 0.3-10 keV band of (8.7+4.6/-3.5)e-17 W/m2 assuming a single power law model with a photon index Gamma = 2.0 and a Galactic column density of 5.6e20 cm-2 at the position of the source. Assuming the luminosity distance of 10.2 Mpc as given in ATEL 9086, this flux corresponds to a luminosity of 1.1e32 W.
The Swift UVOT clearly detected the supernova candidate as well with the following observed magnitudes in the Vega system:
V: 15.798+/-0.079; B: 16.449+/-0.058; U: 15.854+/-0.061; UVW1: 16.656+/-0.069; UVM2: 17.598+/-0.135; UVW2: 17.615+/-0.088.
We would like to thank Neil Gehrels for approving our Swift ToO (target ID 34565) and the Swift Science Operations Team for performing the observation. We also acknowledge the use of the Swift XRT product tool at the University of Leicester (Evens et al., 2009, MNRAS 397, 1177).
