{
  "bibcode": "2023GCN.33135....1P",
  "body": "M. Perri (SSDC & INAF-OAR), A. Tohuvavohu (U. Toronto), D.N. Burrows\n(PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.\nLeicester), A.P. Beardmore (U. Leicester), V. D'Elia (SSDC & INAF-OAR),\nB. Sbarufatti (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf\nof the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nSwift/BAT-GUANO-detected burst GRB 221231A, collecting 5.0 ks of Photon\nCounting (PC) mode data between T0+32.4 ks and T0+44.3 ks. \n\nFive uncatalogued X-ray sources have been detected, however none of\nthem is above the RASS limit or shows definitive signs of fading.\nTherefore, at the present time we cannot identify which, if any, is the\nafterglow. Sources 2 and 5 are inside the error box of Swift/BAT-GUANO,\nbut source 5 is associated with a known source. Details of these\nsources are given below:\n\nSource 1:\n  RA (J2000.0):  336.3458  =  22:25:22.98\n  Dec (J2000.0): +25.1723  =  +25:10:20.3\n  Error: 6.5 arcsec (radius, 90% conf.)\n  Count-rate: (9.1 [+7.3, -5.4])e-4 ct s^-1   \n  Distance: 303 arcsec from Swift/BAT-GUANO position.\n\nSource 2:\n  RA (J2000.0):  336.2560  =  22:25:1.44\n  Dec (J2000.0): +25.1298  =  +25:07:47.2\n  Error: 3.1 arcsec (radius, 90% conf. [Enhanced position])\n  Count-rate: 0.0107 [+0.0022, -0.0020] ct s^-1   \n  Distance: 34 arcsec from Swift/BAT-GUANO position.\n  Flux: (5.44 [+1.13, -1.00])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\n\nSource 3:\n  RA (J2000.0):  336.2019  =  22:24:48.46\n  Dec (J2000.0): +25.0298  =  +25:01:47.3\n  Error: 5.4 arcsec (radius, 90% conf.)\n  Count-rate: (1.87 [+0.97, -0.73])e-3 ct s^-1\t \n  Distance: 435 arcsec from Swift/BAT-GUANO position.\n  Flux: (7.8 [+4.0, -3.1])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 4:\n  RA (J2000.0):  336.2146  =  22:24:51.50\n  Dec (J2000.0): +25.2635  =  +25:15:48.7\n  Error: 8.9 arcsec (radius, 90% conf.)\n  Count-rate: (1.48 [+0.87, -0.64])e-3 ct s^-1\t \n  Distance: 474 arcsec from Swift/BAT-GUANO position.\n  Flux: (2.7 [+1.6, -1.2])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 5:\n  RA (J2000.0):  336.2452  =  22:24:58.84\n  Dec (J2000.0): +25.1872  =  +25:11:14.1\n  Error: 5.7 arcsec (radius, 90% conf.)\n  Count-rate: (5.6 [+1.8, -1.5])e-3 ct s^-1   \n  Distance: 182 arcsec from Swift/BAT-GUANO position.\n  Flux: (1.12 [+0.37, -0.30])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\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/00021534.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 33135,
  "createdOn": 1672592071000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 221231A: Swift-XRT observations",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 221231A"
}