{
  "submittedHow": "email",
  "circularId": 42417,
  "subject": "GRB 251022A: Swift-XRT detection of GOTO25iym",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "bibcode": "2025GCN.42417....1B",
  "eventId": "GRB 251022A",
  "body": "D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara (PSU), J.P. Osborne\n(U. Leicester), K.L. Page (U. Leicester), M. Capalbi (INAF-OAR), M.\nPerri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR) 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 251022A in a series of observations tiled\non the sky.  The total exposure time is  4.6 ks, distributed over 4\ntiles; the maximum exposure at a single sky location in the tiling was\n2.5 ks. The data were collected between T0+26.7 ks and T0+71.7 ks, and\nare entirely in Photon Counting (PC) mode. \n\nSeven uncatalogued X-ray sources have been detected, however none of\nthem is above the RASS limit or shows definitive signs of fading in the\nX-rays. \n\nSource 4 is 2.6 arcsec from the reported optical transient GOTO25iym\n(O'Neill et al., GCN Circ. 42386) and thus is likely the counterpart to\nthat transient and the GRB afterglow, though we cannot at present\nconfirm fading in X-rays. The details of this source are:\n\nSource 4:\n  RA (J2000.0):  65.4968  =  04h 21m 59.23s\n  Dec (J2000.0): -18.9188  =  -18d 55' 07.8\"\n  Error: 4.8 arcsec (radius, 90% conf.)\n  Count-rate: 0.0110 [+0.0026, -0.0025] ct s^-1   \n  Distance: 1463 arcsec from Fermi/LAT position.\n  Flux: (2.96 [+0.71, -0.67])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nThe other 6 uncatalogued sources detected are enumerated below:\n\nSource 1:\n  RA (J2000.0):  65.0135  =  04h 20m 03.25s\n  Dec (J2000.0): -19.3306  =  -19d 19' 50.1\"\n  Error: 6.3 arcsec (radius, 90% conf. [Enhanced position])\n  Count-rate: 0.0173 [+0.0061, -0.0050] ct s^-1   \n  Distance: 1247 arcsec from Fermi/LAT position.\n  Flux: (3.5 [+1.2, -1.0])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 2:\n  RA (J2000.0):  65.0984  =  04h 20m 23.62s\n  Dec (J2000.0): -19.2625  =  -19d 15' 45.2\"\n  Error: 5.4 arcsec (radius, 90% conf.)\n  Count-rate: 0.0115 [+0.0046, -0.0037] ct s^-1   \n  Distance: 971 arcsec from Fermi/LAT position.\n  Flux: (4.4 [+1.8, -1.4])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 5:\n  RA (J2000.0):  65.3796  =  04h 21m 31.10s\n  Dec (J2000.0): -18.9857  =  -18d 59' 08.4\"\n  Error: 6.0 arcsec (radius, 90% conf.)\n  Count-rate: (7.7 [+2.6, -2.1])e-3 ct s^-1   \n  Distance: 1167 arcsec from Fermi/LAT position.\n  Flux: (2.17 [+0.72, -0.60])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 6:\n  RA (J2000.0):  65.5456  =  04h 22m 10.93s\n  Dec (J2000.0): -19.1086  =  -19d 06' 30.8\"\n  Error: 6.5 arcsec (radius, 90% conf.)\n  Count-rate: (6.0 [+2.5, -2.0])e-3 ct s^-1   \n  Distance: 917 arcsec from Fermi/LAT position.\n  Flux: (9.1 [+3.9, -3.0])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 8:\n  RA (J2000.0):  65.4382  =  04h 21m 45.16s\n  Dec (J2000.0): -19.0268  =  -19d 01' 36.6\"\n  Error: 7.8 arcsec (radius, 90% conf.)\n  Count-rate: (3.2 [+1.8, -1.3])e-3 ct s^-1   \n  Distance: 1038 arcsec from Fermi/LAT position.\n  Flux: (6.8 [+3.9, -2.8])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 9:\n  RA (J2000.0):  65.3956  =  04h 21m 34.95s\n  Dec (J2000.0): -19.0576  =  -19d 03' 27.4\"\n  Error: 6.3 arcsec (radius, 90% conf.)\n  Count-rate: (3.6 [+2.1, -1.5])e-3 ct s^-1   \n  Distance: 910 arcsec from Fermi/LAT position.\n  Flux: (1.15 [+0.65, -0.48])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nTwo catalogued sources were also detected.\n\nThe results of the XRT-team automatic analysis of the tiled XRT\nobservations, including a position-specific upper limit calculator, are\navailable at https://www.swift.ac.uk/xrt_products/TILED_GRB00139.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "createdOn": 1761293536629
}