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GCN Circular 32296

Subject
GRB 220627A: Swift-XRT afterglow detection
Date
2022-06-30T00:29:37Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J. D. Gropp (PSU), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J.A.
Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato
(INAF-OAB) 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 220627A (Di Lalla et al. GCN Circ. 32283),
collecting 4.9 ks of Photon Counting (PC) mode data between T0+44.3 ks
and T0+148.8 ks. 

Fourteen uncatalogued X-ray sources are detected, of which one ("Source
3") is fading with >3-sigma significance, and is therefore likely the
GRB afterglow. Using 1679 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 = 201.36878,
-32.42624 which is equivalent to:

RA (J2000): 13h 25m 28.51s
Dec(J2000): -32d 25' 34.5"

with an uncertainty of 3.1 arcsec (radius, 90% confidence). This
position is 9.6 arcmin from the Fermi/LAT position and is consistent
with the previously detected candidate afterglow (GCN Circ 32289).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.4 (+0.8, -0.5).

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021506.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021506.

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