GCN Circular 28205
Subject
GRB 200803A: Swift-XRT afterglow detection
Date
2020-08-03T20:28:04Z (4 years ago)
From
Andy Beardmore at U Leicester <ab271@leicester.ac.uk>
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini
(INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), B.
Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU) and P.A. Evans
(U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 200803A (Cutini et al. GCN Circ. 28203) in
a series of observations tiled on the sky. The total exposure time is
3.5 ks, distributed over 4 tiles; the maximum exposure at a single sky
location was 1.6 ks. The data were collected between T0+36.3 ks and
T0+46.6 ks, and are entirely in Photon Counting (PC) mode.
Five uncatalogued X-ray sources are detected, of which one ("Source 1")
is above the RASS limit, and is therefore likely the GRB afterglow.
Using 812 s of PC mode data and 2 UVOT images, we find an enhanced XRT
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 311.09390, -62.94478 which is
equivalent to:
RA (J2000): 20h 44m 22.54s
Dec(J2000): -62d 56' 41.2"
with an uncertainty of 2.8 arcsec (radius, 90% confidence). This
position is 9.7 arcmin from the Fermi/LAT position and 1.5 arcsec from
the MASTER optical counterpart reported by Lipunov et al. (GCN Circ.
28202).
The light curve can be modelled with a power-law decay with a decay
index of alpha=3.30 (+0.06, -2.56).
If the light curve continues to decay with a power-law decay index of
3.30, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1
The results of the XRT-team automatic analysis of the likely afterglow
are at https://www.swift.ac.uk/xrt_products/TILED_GRB00092/Source1.php.
The results of the full analysis of the tiled XRT observations are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00092.
This circular is an official product of the Swift-XRT team.