{
  "bibcode": "2021GCN.29835....1B",
  "body": "A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne\n(U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi\t(INAF-IASFPA) ,\nM. Capalbi (INAF-IASFPA), B. Sbarufatti (PSU), D.N. Burrows (PSU), J.\nD. Gropp (PSU) and S. Laha report on behalf of the Swift-XRT team:\n\nWe have analysed 6.8 ks of XRT data for GRB 210419A (Laha et al. GCN\nCirc. 29828), from 134 s to 64.1 ks after the  BAT trigger. The data\ncomprise 143 s in Windowed Timing (WT) mode with the remainder in\nPhoton Counting (PC) mode. The enhanced XRT position for this burst was\ngiven by Osborne et al. (GCN Circ. 29830).\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=1.0 (+/-0.3).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.71 (+0.11, -0.10). The\nbest-fitting absorption column is  1.4 (+0.4, -0.3) x 10^21 cm^-2, in\nexcess of the Galactic value of 7.8 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 2.60 (+0.29, -0.27)\nand a best-fitting absorption column of 1.9 (+0.7, -0.6) x 10^21 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 2.6 x 10^-11 (4.8 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.9 (+0.7, -0.6) x 10^21 cm^-2\nGalactic foreground: 7.8 x 10^20 cm^-2\nExcess significance: 2.9 sigma\nPhoton index:\t     2.60 (+0.29, -0.27)\n\nIf the light curve continues to decay with a power-law decay index of\n1.0, the count rate at T+24 hours will be 4.3 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x\n10^-13 (2.1 x 10^-13) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01044032.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 29835,
  "createdOn": 1618886339000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 210419A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 210419A"
}