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GCN Circular 19464

GRB 160521B: Swift-XRT afterglow detection
2016-05-25T19:12:11Z (8 years ago)
Andrea Melandri at INAF-OAB <>
K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A.
D'Ai (INAF-IASFPA), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.A.
Kennea (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester)
and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has conducted further observations of the field of the
Fermi/LAT-detected burst GRB 160521B (Axelsson et al. GCN Circ. 19444).
The observations now extend from T0+41.9 ks to T0+346.3 ks. The source
previously reported by Page et al. (GCN Circ. 19448), "Source 1", is
fading with 3-sigma significance, and is therefore likely the GRB
afterglow.  The position of this source is RA, Dec=147.6665, +79.0305
which is equivalent to:

RA (J2000): 09:50:39.96
Dec(J2000): +79:01:49.7

with an uncertainty of 4.2 arcsec (radius, 90% confidence).  This
position is 5.9 arcmin from the Fermi/LAT position. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.7 (+0.7, -0.4).

The results of the XRT-team automatic analysis of the likely afterglow
are 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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