{
  "bibcode": "2011GCN.11517....1D",
  "body": "V. D'Elia, G. Stratta (ASDC) and S. R. Oates (MSSL-UCL) report on behalf\nof the Swift-XRT team:\n\nWe have analysed 18.8 ks of XRT data for GRB 110102A (Oates et\nal., GCN Circ. 11509), from 139 s to 47.5 ks after the  BAT trigger.\nThe data comprise 400 s in Windowed Timing (WT) mode with the\nremainder in Photon Counting (PC) mode. The enhanced XRT position for\nthis burst was given by Goad et al. (GCN. Circ 11510).\n\nThe light curve shows an intital flaring activity, possibly associated\nto the prompt event, followed by a canonical steep-flat-steep\nbehaviour, which can be modelled with double broken power-law\ndecay. The initial decay index is alpha= 8.6. At T+450 (+/- 0.05) s the\ndecay flattens to an alpha of 0.49 (+/-0.03). At T+11.38 (+/- 0.01) ks  \nthe decay steepens again to an alpha of 1.53 (+0.07 -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 1.48 (+/-0.04). The\nbest-fitting absorption column is  7.8 (+/- 1) x 10^20 cm^-2, in\nexcess of the Galactic value of 4.8 x 10^20 cm^-2 (Kalberla et al.\n2005). The PC mode spectrum has a photon index of 2.27 (+/-0.07) and a\nbest-fitting absorption column of 1.28 (+/- 0.17) x 10^21 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 3.6 x 10^-11 (5.8 x 10^-11) erg cm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of 1.6,\nthe count rate at T+48 hours will be 0.012 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of\n4.3 x 10^-13 (7.0 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/00441454.\n\nThis circular is an official product of the Swift-XRT team.\n\n[GCN OPS NOTE(04jan11):  Per author's request, the \"4.3 x 10^-12 (2.1 x 10^-13)\"\nin the 4th paragraph was changed to \"4.3 x 10^-13 (7.0 x 10^-13)\".]",
  "circularId": 11517,
  "createdOn": 1294110300000,
  "email": "delia@asdc.asi.it",
  "subject": "GRB 110102A: Swift-XRT refined Analysis",
  "submitter": "Valerio D'Elia at ASDC  <delia@asdc.asi.it>",
  "eventId": "GRB 110102A"
}