{
  "bibcode": "2017GCN.21267....1C",
  "body": "A. Cholden-Brown (PSU), P.A. Evans (U. Leicester), S.L. Gibson (U.\nLeicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), P.\nD'Avanzo (INAF-OAB), V. D'Elia (ASDC), S. J. LaPorte (PSU), J.A. Kennea\n(PSU) and F.E. Marshall report on behalf of the Swift-XRT team:\n\nWe have analysed 9.4 ks of XRT data for GRB 170626A (Marshall et al.\nGCN Circ. 21264), from 51 s to 28.8 ks after the  BAT trigger. The data\ncomprise 1.2 ks in Windowed Timing (WT) mode (the first 6 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The refined XRT position is RA, Dec = 165.3936, +56.4768 which is\nequivalent to:\n\nRA (J2000): 11 01 34.46\nDec(J2000): +56 28 36.5\n\nwith an uncertainty of 3.5 arcsec (radius, 90% confidence).\n\nThe late-time light curve (from T0+5.4 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.22 (+/-0.09).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.019 (+/-0.025). The\nbest-fitting absorption column is  3.2 (+/-0.5) x 10^20 cm^-2, in\nexcess of the Galactic value of 6.7 x 10^19 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.73 (+/-0.08) and a\nbest-fitting absorption column of 3.2 (+1.8, -1.7) x 10^20 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 3.7 x 10^-11 (3.9 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     3.2 (+1.8, -1.7) x 10^20 cm^-2\nGalactic foreground: 6.7 x 10^19 cm^-2\nExcess significance: 2.4 sigma\nPhoton index:\t     1.73 (+/-0.08)\n\nIf the light curve continues to decay with a power-law decay index of\n1.22, the count rate at T+24 hours will be 0.039 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x\n10^-12 (1.5 x 10^-12) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00758766.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 21267,
  "createdOn": 1498507314000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 170626A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 170626A"
}