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GCN Circular 30379

GRB 210704A: Swift-XRT afterglow detection
2021-07-05T15:34:15Z (3 years ago)
Phil Evans at U of Leicester <>
A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto),
B. Sbarufatti (PSU), 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 210704A (Berretta et al. GCN Circ. 30375),
collecting 2.6 ks of Photon Counting (PC) mode data between T0+53.5 ks
and T0+61.1 ks. 

An uncatalogued X-ray source is detected and is above the 2SXPS 3-sigma
upper limit at this position, and is therefore likely the GRB
afterglow. Using 2378 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 = 159.02219, +57.21636
which is equivalent to:

RA (J2000): 10h 36m 05.33s
Dec(J2000): +57d 12' 58.9"

with an uncertainty of 3.2 arcsec (radius, 90% confidence). This
position is 5.9 arcmin from the Fermi/LAT position.  We cannot
determine at the present time whether the source is fading.

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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