{
  "body": "M.G. Bernardini (INAF-OAB), J.A. Kennea (PSU), A. Tohuvavohu (U.\nToronto), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore\n(U. Leicester), E. Ambrosi  (INAF-IASFPA) , M. Capalbi (INAF-IASFPA)\nand P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nFermi/GBM,SVOM/ECLAIRs,SVOM/GRM-detected burst GRB 240821A\n(GCN circ. 37219, 37220, 37226, 37227, 37239), collecting\n5.0 ks of Photon Counting (PC) mode data between T0+91.4 ks\nand T0+153.6 ks. \n\nFour uncatalogued X-ray sources have been detected, however none of\nthem is above the RASS limit or shows definitive signs of fading.\nSource 2 is consistent with the position of galaxy SDSS\nJ233641.30-100258.0.\nThe XRT detected sources are detected also in EP-FXT data (GCN Circ.\n37230).\nThe Swift/XRT and EP-FXT fluxes are consistent within the errors.\nTherefore, at the present time we cannot identify which, if any, is the\nafterglow. \nDetails of these sources are given below:\n\nSource 1:\n  RA (J2000.0):  354.2899  =  23:37:9.58\n  Dec (J2000.0): -10.0537  =  -10:03:13.2\n  Error: 7.1 arcsec (radius, 90% conf.)\n  Count-rate: (1.90 [+0.98, -0.74])e-3 ct s^-1\t \n  Distance: 501 arcsec from SVOM/ECLAIRs position.\n  Flux: (6.2 [+3.2, -2.4])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 2:\n  RA (J2000.0):  354.1713  =  23:36:41.12\n  Dec (J2000.0): -10.0495  =  -10:02:58.0\n  Error: 7.4 arcsec (radius, 90% conf.)\n  Count-rate: (2.49 [+1.09, -0.86])e-3 ct s^-1\t \n  Distance: 513 arcsec from SVOM/ECLAIRs position.\n  Flux: (8.2 [+3.6, -2.8])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 3:\n  RA (J2000.0):  354.2700  =  23:37:4.80\n  Dec (J2000.0): -10.1882  =  -10:11:17.6\n  Error: 10.3 arcsec (radius, 90% conf.)\n  Count-rate: (1.53 [+0.83, -0.63])e-3 ct s^-1\t \n  Distance: 144 arcsec from SVOM/ECLAIRs position.\n  Flux: (6.6 [+3.6, -2.7]e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nSource 4:\n  RA (J2000.0):  354.1714  =  23:36:41.14\n  Dec (J2000.0): -10.1776  =  -10:10:39.4\n  Error: 5.8 arcsec (radius, 90% conf.)\n  Count-rate: (1.30 [+0.80, -0.59])e-3 ct s^-1\t \n  Distance: 207 arcsec from SVOM/ECLAIRs position.\n  Flux: (3.0 [+1.8, -1.3])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)\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/00021704.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "subject": "GRB 240821A: Swift-XRT observations",
  "submittedHow": "email",
  "eventId": "GRB 240821A",
  "circularId": 37249,
  "createdOn": 1724434170445,
  "bibcode": "2024GCN.37249....1B",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>"
}