{
  "bibcode": "2020GCN.26852....1G",
  "body": "J. D. Gropp (PSU), A. Tohuvavohu (U. Toronto), J.A. Kennea (PSU), P.A.\nEvans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.\nLeicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo\n(INAF-OAB) and E. Sonbas report on behalf of the Swift-XRT team:\n\nWe have analysed 6.4 ks of XRT data for GRB 200122A (Sonbas et al. GCN\nCirc. 26844), from 63 s to 35.2 ks after the  BAT trigger. The data\ncomprise 296 s in Windowed Timing (WT) mode (the first 8 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. 26846).\n\nThe late-time light curve (from T0+5.3 ks) can be modelled with a\npower-law decay with a decay index of alpha=0.67 (+0.11, -0.10).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.84 (+/-0.05). The\nbest-fitting absorption column is  1.44 (+/-0.07) x 10^22 cm^-2, in\nexcess of the Galactic value of 1.5 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 2.25 (+/-0.14) and a\nbest-fitting absorption column of 1.70 (+0.18, -0.17) x 10^22 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 5.1 x 10^-11 (1.3 x 10^-10) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.70 (+0.18, -0.17) x 10^22 cm^-2\nGalactic foreground: 1.5 x 10^20 cm^-2\nExcess significance: 16.2 sigma\nPhoton index:\t     2.25 (+/-0.14)\n\nIf the light curve continues to decay with a power-law decay index of\n0.67, the count rate at T+24 hours will be 0.11 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.7 x\n10^-12 (1.5 x 10^-11) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00950330.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 26852,
  "createdOn": 1579699252000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 200122A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 200122A"
}