{
  "subject": "GRB 150301B: Swift-XRT refined Analysis",
  "eventId": "GRB 150301B",
  "bibcode": "2015GCN.17533....1M",
  "createdOn": 1425325804000,
  "circularId": 17533,
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "email": "pae9@leicester.ac.uk",
  "body": "A. Maselli  (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows\n(PSU), J.A. Kennea (PSU), A. Amaral-Rogers (U. Leicester), J.P. Osborne\n(U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), P.\nD'Avanzo (INAF-OAB) and A.Y. Lien report on behalf of the Swift-XRT\nteam:\n\nWe have analysed 5.7 ks of XRT data for GRB 150301B (Lien et al. GCN\nCirc. 17515), from 67 s to 69.5 ks after the  BAT trigger. The data\ncomprise 67 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 enhanced XRT position for this burst was given by Evans et\nal. (GCN Circ. 17520).\n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.11 (+0.05, -0.04).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.81 (+0.18, -0.10). The\nbest-fitting absorption column is  consistent with the Galactic value\nof 6.2 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 3.7 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nGalactic foreground: 6.2 x 10^20 cm^-2\nIntrinsic column:    6 (+/-14) x 10^20 cm^-2 at z=1.5169\nPhoton index:\t     1.81 (+0.18, -0.10)\n\nIf the light curve continues to decay with a power-law decay index of\n1.11, the count rate at T+24 hours will be 3.3 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x\n10^-13 (1.4 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/00633180.\n\nThis circular is an official product of the Swift-XRT team."
}