{
  "createdOn": 1750071410121,
  "eventId": "GRB 250615A",
  "subject": "GRB 250615A: Swift-XRT refined Analysis",
  "bibcode": "2025GCN.40745....1B",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "body": "D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), J.P.\nOsborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini\n(INAF-OAB), E. Ambrosi\t(INAF-IASFPA) , M. Capalbi (INAF-OAR) and P.A.\nEvans report on behalf of the Swift-XRT team:\n\nWe have analysed 6.2 ks of XRT data for GRB 250615A, from 93 s to 40.3\nks after the   trigger. The data comprise 106 s in Windowed Timing (WT)\nmode with the remainder in Photon Counting (PC) mode. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.62 (+0.07, -0.06).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.62 (+0.27, -0.26). The\nbest-fitting absorption column is  2.4 (+0.6, -0.5) x 10^22 cm^-2, in\nexcess of the Galactic value of 5.5 x 10^21 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 2.0 (+0.4, -0.3) and\na best-fitting absorption column of 2.4 (+0.7, -0.6) x 10^22 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 6.7 x 10^-11 (1.5 x 10^-10) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.4 (+0.7, -0.6) x 10^22 cm^-2\nGalactic foreground: 5.5 x 10^21 cm^-2\nExcess significance: 5.3 sigma\nPhoton index:\t     2.0 (+0.4, -0.3)\n\nIf the light curve continues to decay with a power-law decay index of\n1.62, the count rate at T+24 hours will be 2.2 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.5 x\n10^-14 (3.3 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01324646.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "circularId": 40745,
  "submittedHow": "email"
}