{
  "bibcode": "2020GCN.26901....1K",
  "body": "J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.\nLeicester), P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), M.G.\nBernardini (INAF-OAB), E. Ambrosi  (INAF-IASFPA) , B. Sbarufatti (PSU),\nD.N. Burrows (PSU) and M.J. Moss report on behalf of the Swift-XRT\nteam:\n\nWe have analysed 8.3 ks of XRT data for GRB 200127A (Moss et al. GCN\nCirc. 26895), from 130 s to 18.2 ks after the  BAT trigger. The data\ncomprise 215 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 refined XRT position is RA, Dec = 295.1933, +44.9008 which is\nequivalent to:\n\nRA (J2000): 19 40 46.40\nDec(J2000): +44 54 02.8\n\nwith an uncertainty of 3.5 arcsec (radius, 90% confidence).\n\nThe light curve can be modelled with a series of power-law decays. The\ninitial decay index is alpha=1.1 (+0.6, -2.6). At T+172 s  the decay\nsteepens to an alpha of 2.58 (+0.18, -0.15) before breaking again at\nT+648 s to a final decay with index alpha=1.32 (+0.09, -0.12).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.98 (+0.05, -0.04). The\nbest-fitting absorption column is  consistent with the Galactic value\nof 2.2 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has\na photon index of 1.75 (+0.12, -0.11) and a best-fitting absorption\ncolumn consistent with the Galactic value. The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 4.1 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.2 (+0.3, -0.0) x 10^21 cm^-2\nGalactic foreground: 2.2 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.75 (+0.12, -0.11)\n\nIf the light curve continues to decay with a power-law decay index of\n1.32, the count rate at T+24 hours will be 1.8 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.6 x\n10^-14 (9.4 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/00952791.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 26901,
  "createdOn": 1580169082000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 200127A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 200127A"
}