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GCN Circular 30399

Subject
GRB 210706A: Swift-XRT afterglow detection
Date
2021-07-07T01:18:21Z (3 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU),
A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri
(INAF-OAB), T. Sbarrato (INAF-OAB), P. D'Avanzo (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
Swift/BAT-GUANO-detected burst GRB 210706A (Tohuvavohu et al. GCN Circ.
30393), collecting 2.8 ks of Photon Counting (PC) mode data between
T0+43.3 ks and T0+50.7 ks. 

Two uncatalogued X-ray sources are detected, of which one ("Source 2")
is believed to be the afterglow. Using 2536 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 = 311.99471, +13.31694 which is equivalent to:

RA (J2000): 20h 47m 58.73s
Dec(J2000): +13d 19' 01.0"

with an uncertainty of 3.2 arcsec (radius, 90% confidence). This
position is 69 arcsec from the Swift/BAT-GUANO position.  The source
has a mean count rate of 1.4e-02 ct/sec; we cannot determine at the
present time whether it is fading.

The field has been previously observed by XRT for the Swift
Gravitational Wave Galaxy Survey (https://www.swift.ac.uk/SGWGS/, GCN
24305). No source was detected at this position on a 2.8 ks integrated
exposure, down to a 3-�� upper limit of 7 e-3 ct s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021455.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021455.

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