TITLE: GCN CIRCULAR NUMBER: 40604 SUBJECT: GRB 250601A: Swift-XRT observations DATE: 25/06/02 08:18:00 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Swift/BAT-detected burst GRB 250601A, collecting 4.6 ks of Photon Counting (PC) mode data between T0+17.2 ks and T0+35.3 ks.
Two uncatalogued X-ray sources have been detected within the estimated 3-sigma Swift/BAT error region (493 arcsec), however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below:
Source 2: RA (J2000.0): 90.2023 = 06:00:48.56 Dec (J2000.0): -57.2379 = -57:14:16.6 Error: 7.3 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (7.8 +/- 1.9)e-3 ct s^-1 Distance: 315 arcsec from Swift/BAT position. Flux: (4.2 +/- 1.0)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 3: RA (J2000.0): 90.0936 = 06:00:22.47 Dec (J2000.0): -57.2778 = -57:16:40.0 Error: 5.7 arcsec (radius, 90% conf.) Count-rate: (3.6 [+1.6, -1.3])e-3 ct s^-1 Distance: 60 arcsec from Swift/BAT position. Flux: (1.00 [+0.45, -0.35])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Another uncatalogued source was also detected, however this was too far from the GRB position to be the afterglow.
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/00021844.
This circular is an official product of the Swift-XRT team.
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