{
  "bibcode": "2021GCN.29705....1B",
  "body": "A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), E. Ambrosi \n(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR),\nJ. D. Gropp (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P.\nOsborne (U. Leicester) and J.D. Gropp report on behalf of the Swift-XRT\nteam:\n\nWe have analysed 6.8 ks of XRT data for GRB 210323A (Gropp et al. GCN\nCirc. 29699), from 88 s to 34.2 ks after the  BAT trigger. The data\ncomprise 25 s in Windowed Timing (WT) mode with the remainder in Photon\nCounting (PC) mode. The enhanced XRT position for this burst was given\nby Evans et al. (GCN Circ. 29704).\n\nThe light curve can be modelled with a series of power-law decays. The\ninitial decay index is alpha=1.69 (+0.17, -0.12). At T+719 s  the decay\nflattens to an alpha of 0.46 (+0.09, -0.25) before breaking again at\nT+12.2 ks to a final decay with index alpha=2.9 (+5.1, -0.6).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.70 (+0.20, -0.19). The\nbest-fitting absorption column is  2.7 (+1.0, -0.8) x 10^21 cm^-2, in\nexcess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 4.4 x 10^-11 (5.6 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.7 (+1.0, -0.8) x 10^21 cm^-2\nGalactic foreground: 1.2 x 10^21 cm^-2\nExcess significance: 3.0 sigma\nPhoton index:\t     1.70 (+0.20, -0.19)\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 2.0 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.9 x\n10^-15 (1.1 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/01038247.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 29705,
  "createdOn": 1616581424000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 210323A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 210323A"
}