{
  "bibcode": "2018GCN.22540....1P",
  "body": "K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri\n(INAF-OAB), P. D'Avanzo (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte\n(PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U.\nLeicester) and E. Troja report on behalf of the Swift-XRT team:\n\nWe have analysed 6.0 ks of XRT data for GRB 180325A (Troja et al. GCN\nCirc. 22532), from 61 s to 29.3 ks after the  BAT trigger. The data\ncomprise 329 s in Windowed Timing (WT) mode (the first 10 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. 22539).\n\nThe late-time light curve (from T0+4.8 ks) can be modelled with a\npower-law decay with a decay index of alpha=2.02 (+0.09, -0.08).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.60 (+/-0.09). The\nbest-fitting absorption column is  1.7 (+0.6, -0.5) x 10^22 cm^-2, at a\nredshift of 2.25, in addition to the Galactic value of 1.3 x 10^20\ncm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index\nof 1.85 (+/-0.09) and a best-fitting absorption column of 1.3 (+/-0.4)\nx 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 3.6 x 10^-11 (4.2 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nGalactic foreground: 1.3 x 10^20 cm^-2\nIntrinsic column:    1.3 (+/-0.4) x 10^22 cm^-2 at z=2.25\nPhoton index:\t     1.85 (+/-0.09)\n\nIf the light curve continues to decay with a power-law decay index of\n2.02, the count rate at T+24 hours will be 7.0 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.5 x\n10^-13 (2.9 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/00817564.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 22540,
  "createdOn": 1521979796000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 180325A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 180325A"
}