{
  "subject": "GRB 250601A: Swift-XRT observations",
  "eventId": "GRB 250601A",
  "submittedHow": "email",
  "bibcode": "2025GCN.40604....1P",
  "createdOn": 1748852280352,
  "circularId": 40604,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "body": "K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), R. Brivio\n(INAF-OAB), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), S. Dichiara\n(PSU), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans (U.\nLeicester) reports on behalf of the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nSwift/BAT-detected burst GRB 250601A, collecting  4.6 ks of Photon\nCounting (PC) mode data between T0+17.2 ks and T0+35.3 ks. \n\nTwo uncatalogued X-ray sources have been detected within the estimated\n3-sigma Swift/BAT error region (493 arcsec), however none of them is\nabove the RASS limit or shows definitive signs of fading. Therefore, at\nthe present time we cannot identify which, if any, is the afterglow.\nDetails of these sources are given below:\n\nSource 2:\n  RA (J2000.0):  90.2023  =  06:00:48.56\n  Dec (J2000.0): -57.2379  =  -57:14:16.6\n  Error: 7.3 arcsec (radius, 90% conf. [Enhanced position])\n  Count-rate: (7.8 +/- 1.9)e-3 ct s^-1\t \n  Distance: 315 arcsec from Swift/BAT position.\n  Flux: (4.2 +/- 1.0)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 3:\n  RA (J2000.0):  90.0936  =  06:00:22.47\n  Dec (J2000.0): -57.2778  =  -57:16:40.0\n  Error: 5.7 arcsec (radius, 90% conf.)\n  Count-rate: (3.6 [+1.6, -1.3])e-3 ct s^-1   \n  Distance: 60 arcsec from Swift/BAT position.\n  Flux: (1.00 [+0.45, -0.35])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nAnother uncatalogued source was also detected, however this was too far\nfrom the GRB position to be the afterglow.\n\nThe results of the XRT-team automatic analysis of the XRT observations,\nincluding a position-specific upper limit calculator, are available at\nhttps://www.swift.ac.uk/ToO_GRBs/00021844.\n\nThis circular is an official product of the Swift-XRT team.\n\n"
}