{
  "submittedHow": "email",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "eventId": "GRB 240418A",
  "circularId": 36181,
  "createdOn": 1713539867287,
  "bibcode": "2024GCN.36181....1T",
  "body": "A. Tohuvavohu (U. Toronto), K.L. Page (U. Leicester), A.P. Beardmore\n(U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR),\nV. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), J. D. Gropp (PSU) and\nP.A. Evans report on behalf of the Swift-XRT team:\n\nWe have analysed 6.1 ks of XRT data for GRB 240418A, from 107 s to 44.9\nks after the  BAT trigger. The data comprise 7 s in Windowed Timing\n(WT) mode (taken while Swift was slewing), with the remainder in Photon\nCounting (PC) mode. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=2.9 (+0.3, -0.4).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.0 (+0.6, -0.4). The\nbest-fitting absorption column is  consistent with the Galactic value\nof 5.3 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 3.2 x 10^-11 (3.5 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     5 (+/-12) x 10^20 cm^-2\nGalactic foreground: 5.3 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     2.0 (+0.6, -0.4)\n\nIf the light curve continues to decay with a power-law decay index of\n2.9, the count rate at T+24 hours will be 1.2 x 10^-8 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.8 x\n10^-19 (4.1 x 10^-19) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01222885.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "subject": "GRB 240418A: Swift-XRT refined Analysis"
}