{
  "bibcode": "2023GCN.33757....1E",
  "createdOn": 1683753576239,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "circularId": 33757,
  "body": "P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), A. D'Ai\n(INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), S.\nDichiara (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), K.L.\nPage (U. Leicester) report on behalf of the Swift-XRT team:\n\nWe have analysed 6.3 ks of XRT data for GRB 230510A, from 52 s to 23.0\nks after the  BAT trigger. The data comprise 250 s in Windowed Timing\n(WT) mode (the first 10 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode. \n\nThe late-time light curve (from T0+4.2 ks) can be modelled with a\npower-law decay with a decay index of alpha=0.92 (+/-0.09).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.19 (+/-0.05). The\nbest-fitting absorption column is  2.53 (+0.17, -0.16) x 10^21 cm^-2,\nin excess of the Galactic value of 1.9 x 10^21 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.99 (+0.13, -0.08)\nand a best-fitting absorption column of 1.938 (+0.454, -0.025) x 10^21\ncm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.5 x 10^-11 (4.8 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.938 (+0.454, -0.025) x 10^21 cm^-2\nGalactic foreground: 1.9 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.99 (+0.13, -0.08)\n\nIf the light curve continues to decay with a power-law decay index of\n0.92, the count rate at T+24 hours will be 0.035 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x\n10^-12 (1.7 x 10^-12) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01167973.\n\nThis circular is an official product of the Swift-XRT team.\n\n",
  "subject": "GRB 230510A: Swift-XRT refined Analysis",
  "eventId": "GRB 230510A"
}