{
  "bibcode": "2021GCN.29295....1E",
  "body": "P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M. Capalbi\n(INAF-IASFPA), M. Perri (SSDC & INAF-OAR), B. Sbarufatti (PSU), D.N.\nBurrows (PSU), J. D. Gropp (PSU), K.L. Page (U. Leicester) and E.\nAmbrosi report on behalf of the Swift-XRT team:\n\nWe have analysed 8.5 ks of XRT data for GRB 210112A (Ambrosi et al. GCN\nCirc. 29289), from 77 s to 46.0 ks after the  BAT trigger. The data\ncomprise 859 s in Windowed Timing (WT) mode with the remainder in\nPhoton Counting (PC) mode. The enhanced XRT position for this burst was\ngiven by Goad et al. (GCN Circ. 29290).\n\nThe late-time light curve (from T0+6.4 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.36 (+/-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 1.56 (+/-0.03). The\nbest-fitting absorption column is  2.34 (+/-0.14) x 10^21 cm^-2, in\nexcess of the Galactic value of 9.5 x 10^19 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 2.01 (+0.10, -0.09)\nand a best-fitting absorption column of 2.8 (+/-0.4) x 10^21 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 3.7 x 10^-11 (5.1 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.8 (+/-0.4) x 10^21 cm^-2\nGalactic foreground: 9.5 x 10^19 cm^-2\nExcess significance: 12.3 sigma\nPhoton index:\t     2.01 (+0.10, -0.09)\n\nIf the light curve continues to decay with a power-law decay index of\n1.36, the count rate at T+24 hours will be 0.046 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x\n10^-12 (2.3 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/01016881.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 29295,
  "createdOn": 1610472018000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 210112A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 210112A"
}