{
  "bibcode": "2015GCN.18030....1S",
  "body": "B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), T.G.R. Roegiers\n(PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), B.P.\nGompertz (U. Leicester), A. Maselli  (INAF-IASFPA), A. Melandri\n(INAF-OAB), P. D'Avanzo (INAF-OAB) and D. Kocevski report on behalf of\nthe Swift-XRT team:\n\nWe have analysed 3.6 ks of XRT data for GRB 150716A (Kocevski et al.\nGCN Circ. 18027), from 66 s to 22.7 ks after the  BAT trigger. The data\ncomprise 126 s in Windowed Timing (WT) mode (the first 11 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The refined XRT position is RA, Dec = 278.4879, -12.9802 which is\nequivalent to:\n\nRA (J2000): 18 33 57.10\nDec(J2000): -12 58 48.9\n\nwith an uncertainty of 4.1 arcsec (radius, 90% confidence).\n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.67 (+0.08, -0.06).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.67 (+0.25, -0.23). The\nbest-fitting absorption column is  1.35 (+0.24, -0.22) x 10^22 cm^-2,\nin excess of the Galactic value of 7.0 x 10^21 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.6 x 10^-11 (1.4 x 10^-10) erg\ncm^-2 count^-1. \n\nA summary of the WT-mode spectrum is thus:\nTotal column:\t     1.35 (+0.24, -0.22) x 10^22 cm^-2\nGalactic foreground: 7.0 x 10^21 cm^-2\nExcess significance: 4.8 sigma\nPhoton index:\t     2.67 (+0.25, -0.23)\n\nIf the light curve continues to decay with a power-law decay index of\n1.67, the count rate at T+24 hours will be 2.4 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.8 x\n10^-15 (3.5 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/00649157.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 18030,
  "createdOn": 1437117544000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 150716A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 150716A"
}