{
  "eventId": "GRB 250830B",
  "circularId": 41613,
  "bibcode": "2025GCN.41613....1B",
  "createdOn": 1756616225475,
  "body": "A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri\n(INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea\n(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 MAXI-detected\nburst GRB 250830B, collecting  2.4 ks of Photon Counting (PC) mode data\nbetween T0+11.0 ks and T0+50.8 ks. This event also triggered Einstein\nProbe around 25 s after MAXI, and was separately designated EP250830a.\n\nOne uncatalogued X-ray source has been detected within the estimated\n3-sigma EP error region (296 arcsec), also consistent with the MAXI\nerror region; it is below the RASS limit and shows no definitive signs\nof fading. Therefore, at the present time we cannot confirm this as the\nafterglow. Details of this source are given below:\n\nSource 1:\n  RA (J2000.0):  105.7399  =  07h 02m 57.59s\n  Dec (J2000.0): -64.8525  =  -64d 51' 09.1\"\n  Error: 3.7 arcsec (radius, 90% conf. [Enhanced position])\n  Count-rate: 0.0323 +/- 0.0046 ct s^-1   \n  Distance: 134 arcsec from EP position.\n  Flux: (1.74 +/- 0.25)e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)\n\nA further uncatalogued X-ray source was also detected, however this was\ntoo far from the EP position to be the 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/00021858.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "subject": "GRB 250830B: Swift-XRT observations",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "submittedHow": "email"
}