{
  "bibcode": "2020GCN.27345....1P",
  "body": "K.L. Page (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (ASDC), V.\nD'Elia (ASDC), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea\n(PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and\nJ.D. Gropp report on behalf of the Swift-XRT team:\n\nWe have analysed 6.0 ks of XRT data for GRB 200306C (Gropp et al. GCN\nCirc. 27326), from 101 s to 18.9 ks after the  BAT trigger. The data\ncomprise 36 s in Windowed Timing (WT) mode (the first 9 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The enhanced XRT position for this burst was given by Osborne et\nal. (GCN Circ. 27342).\n\nThe late-time light curve (from T0+5.5 ks) can be modelled with a\npower-law decay with a decay index of alpha=2.2 (+0.4, -0.3).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.56 (+0.11, -0.10). The\nbest-fitting absorption column is  4.1 (+3.0, -2.2) x 10^20 cm^-2,\nconsistent with the Galactic value of 1.9 x 10^20 cm^-2 (Willingale et\nal. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 4.2 x 10^-11 (4.4 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     4.1 (+3.0, -2.2) x 10^20 cm^-2\nGalactic foreground: 1.9 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.56 (+0.11, -0.10)\n\nIf the light curve continues to decay with a power-law decay index of\n2.2, the count rate at T+24 hours will be 4.4 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x\n10^-14 (1.9 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/00960102.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 27345,
  "createdOn": 1583622123000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 200306C: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 200306C"
}