{
  "createdOn": 1770653020907,
  "body": "A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo\n(INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi  (INAF-IASFPA), J.A.\nKennea (PSU), D.N. Burrows (PSU), S. Lanava (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\nFermi/LAT-detected burst GRB 260208B, collecting  1.6 ks of Photon\nCounting (PC) mode data between T0+33.1 ks and T0+44.4 ks. \n\nOne uncatalogued X-ray source has been detected within the estimated\n3-sigma Fermi/LAT error region (354 arcsec), it is below the RASS limit\nand shows no definitive signs of fading. Details of this source are\ngiven below:\n\nSource 1:\n  RA (J2000.0):  99.6189  =  06h 38m 28.55s\n  Dec (J2000.0): -13.7743  =  -13d 46' 27.4\"\n  Error: 3.1 arcsec (radius, 90% conf. [Enhanced position])\n  Count-rate: 0.0338 +/- 0.0067 ct s^-1   \n  Distance: 238 arcsec from Fermi/LAT position.\n  Flux: (1.63 +/- 0.32)e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nThe flux reported by EP-WXT for this source at 74.7 ks after the\ntrigger (GCN Circ. 43663) is about a factor of 10 fainter than this XRT\nmeasurement, however, which suggests it is indeed the GRB 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/00021909. We note that the large\nnumber of spurious sources was due to unusually high background.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "circularId": 43671,
  "eventId": "GRB 260208B",
  "submittedHow": "email",
  "subject": "GRB 260208B: Swift-XRT observations",
  "bibcode": "2026GCN.43671....1B",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>"
}