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GCN Circular 32510

Subject
GRB 220831A: Swift-XRT observations
Date
2022-09-01T16:49:42Z (2 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
S. Dichiara (PSU), A.P. Beardmore (U. Leicester), E. Ambrosi 
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR),
J. D. Gropp (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P.
Osborne (U. Leicester) 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-detected burst GRB 220831A (Tohuvavohu et al. GCN Circ.
32506), collecting 5.0 ks of Photon Counting (PC) mode data between
T0+51.2 ks and T0+78.8 ks. 

No X-ray sources have been detected consistent with being within 98
arcsec of the Swift/BAT position. The 3-sigma upper limit in the field
ranges from ~0.002 to ~0.003 ct s^-1, corresponding to a 0.3-10 keV
observed flux of 8.1e-14 to 1.1e-13 erg cm^-2 s^-1 (assuming a typical
GRB spectrum).

We report, however, the presence of a low-significance source, at the
following position:
RA (J2000.0):  24.25359  = 01:37:00.86
Dec (J2000.0): -41.59325 = -41:35:35.70
Error: 6.8 arcsec (radius, 90% conf.)
Distance: 41 arcsec from Swift-BAT position.

Given the low-significance detection, we cannot state at the present
stage if this detection is real or spurious.

Six uncatalogued sources were detected too far from the GRB position to
be likely afterglow candidates.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021512.

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