{
  "submittedHow": "email",
  "body": "S. Lanava (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),\nA.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia\n(SSDC & INAF-OAR), B. Sbarufatti (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 Swift/BAT-GUANO\n(Ronchini et al., GCN 43377) and Fermi/GBM (Fermi GBM team, GCN 43370;\nPalafox et al., GCN 43384) detected burst GRB 260111A, collecting  2.8\nks of Photon Counting (PC) mode data between T0+94.3 ks and T0+104.8\nks. \n\nOne uncatalogued X-ray source has been detected within the estimated\n3-sigma Swift/BAT error region (493 arcsec), it is below the RASS limit\nand shows no definitive signs of fading. A source consistent with the\nposition of XRT source 2 has been reported in the optical with\nCOLIBRÍ,  suggesting it could be the GRB afterglow (Ducoin et al., GCN\n43386). \n\nDetails of this source are given below:\n\nSource 2:\n  RA (J2000.0):  229.5858  =  15h 18m 20.60s\n  Dec (J2000.0): +51.9736  =  +51d 58' 24.8\"\n  Error: 6.3 arcsec (radius, 90% conf.)\n  Count-rate: (5.6 [+2.4, -1.9])e-3 ct s^-1   \n  Distance: 27 arcsec from Swift/BAT position.\n  Flux: (1.56 [+0.66, -0.53])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nA catalogued source was also detected within the estimated 3-sigma\nSwift/BAT error region (493 arcsec).\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/00021897.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "eventId": "GRB 260111A",
  "createdOn": 1768302095158,
  "subject": "GRB 260111A: Swift-XRT observations",
  "bibcode": "2026GCN.43388....1L",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "circularId": 43388
}