TITLE: GCN CIRCULAR NUMBER: 30734 SUBJECT: GRB 210827A: Swift-XRT observations DATE: 21/08/28 08:58:36 GMT FROM: Paolo D'Avanzo at INAF - OAB paolo.davanzo@inaf.it
J. D. Gropp (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), A. Tohuvavohu (U. Toronto) 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 210827A (James DeLaunay et al. GCN Circ. 30732), collecting 2.3 ks of Photon Counting (PC) mode data between T0+44.4 ks and T0+50.4 ks.
One uncatalogued X-ray source has been detected consistent with being within 296 arcsec of the Swift/BAT-GUANO position, it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below:
Source 3: RA (J2000.0): 174.9003 = 11:39:36.07 Dec (J2000.0): +55.7239 = +55:43:26.2 Error: 3.8 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.0103 +/- 0.0025 ct s^-1 Distance: 225 arcsec from Swift/BAT-GUANO position. Flux: (4.8 +/- 1.2)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Four uncatalogued sources were also 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/00021461.
This circular is an official product of the Swift-XRT team.