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GCN Circular 30399

GRB 210706A: Swift-XRT afterglow detection
2021-07-07T01:18:21Z (3 years ago)
Aaron Tohuvavohu at U Toronto <>
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 (, 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
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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