{
  "bibcode": "2025GCN.41194....1W",
  "createdOn": 1753783163658,
  "eventId": "GRB 250728A",
  "version": 2,
  "body": "M.A. Williams (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.\nLeicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAR), T.\nSbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), S. Dichiara (PSU), J.A.\nKennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the\nSwift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nFermi/GBM-detected burst GRB 250728A, collecting  3.1 ks of Photon\nCounting (PC) mode data between T0+14.6 ks and T0+28.2 ks. \n\nOne uncatalogued X-ray source has been detected within the estimated\n3-sigma Swift/BAT-GUANO error region (394 arcsec), it is below the RASS limit\nand shows no definitive signs of fading. Therefore, at the present time\nwe cannot confirm this as the afterglow. Details of this source are\ngiven below:\n\nSource 3:\n  RA (J2000.0):  260.9895  =  17:23:57.48\n  Dec (J2000.0): +16.2004  =  +16:12:01.6\n  Error: 6.7 arcsec (radius, 90% conf.)\n  Count-rate: (1.98 [+1.26, -0.93])e-3 ct s^-1\t \n  Distance: 154 arcsec from Fermi/GBM position.\n  Flux: (1.34 [+0.85, -0.63])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nTwo uncatalogued sources were also detected too far from the BAT\nposition to be likely afterglow candidates.\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/00021852.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "circularId": 41194,
  "format": "text/plain",
  "editedOn": 1753794241943,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "subject": "GRB 250728A: Swift-XRT observations",
  "submittedHow": "email",
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of K.L. Page at U Leicester <klp5@leicester.ac.uk>"
}