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GCN Circular 23305

GRB 181003A: Swift-XRT afterglow detection
2018-10-03T18:08:13Z (5 years ago)
Andy Beardmore at U Leicester <>
A. Tohuvavohu (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U.
Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo
(INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 181003A (Beardmore et al. GCN Circ.
23295), collecting 8.6 ks of Photon Counting (PC) mode data between
T0+3.1 ks and T0+34.3 ks. 

Six uncatalogued X-ray sources are detected consistent with being
within 296 arcsec of the Swift/BAT position, of which one ("Source 1")
is fading with 3-sigma significance, and is therefore likely the GRB
afterglow. Using 1905 s of PC mode data and 1 UVOT image, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 52.52869, -33.96466
which is equivalent to:

RA (J2000): 03h 30m 06.89s
Dec(J2000): -33d 57' 52.8"

with an uncertainty of 6.3 arcsec (radius, 90% confidence). This
position is 4.0 arcmin from the Swift/BAT position.  The source is
fading with alpha >0.8.

The results of the XRT-team automatic analysis are available at
The results of the full analysis of the XRT observations are available

This circular is an official product of the Swift-XRT team.
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