{
  "bibcode": "2016GCN.18795....1I",
  "body": "L. Izzo (URoma/ICRA), V. D'Elia (ASDC), P. D'Avanzo (INAF-OAB), T.G.R.\nRoegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU), A.P. Beardmore\n(U. Leicester), S.L. Gibson (U. Leicester), A. D'Ai (INAF-IASFPA) and\nP.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the MAXI-detected\nburst GRB 160101A (Itoh et al. GCN Circ. 18793) in a series of\nobservations tiled on the sky. The total exposure time is 1.7 ks,\ndistributed over 7 tiles; the maximum exposure at a single sky location\nwas 512 s. The data were collected between T0+13.2 ks and T0+19.6 ks,\nand are entirely in Photon Counting (PC) mode. \n\nAn uncatalogued X-ray source is detected and is above the RASS limit,\nand is therefore likely the GRB afterglow.  The position of this source\nis RA, Dec=219.6506, -13.8154 which is equivalent to:\n\nRA (J2000): 14:38:36.14\nDec(J2000): -13:48:55.5\n\nwith an uncertainty of 3.7 arcsec (radius, 90% confidence).  This\nposition is 4.8 arcmin from the MAXI position.\tThe source has a mean\ncount rate of 3.9e-01 ct/sec; we cannot determine at the present time\nwhether it is fading.\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.5 (+0.5, -0.3). The\nbest-fitting absorption column is  1.20 (+2.17, -0.29) x 10^21 cm^-2,\nconsistent with the Galactic value of 9.1 x 10^20 cm^-2 (Willingale et\nal. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 4.6 x 10^-11 (5.1 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.20 (+2.17, -0.29) x 10^21 cm^-2\nGalactic foreground: 9.1 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.5 (+0.5, -0.3)\n\nThe results of the XRT-team automatic analysis of the likely afterglow\nare at http://www.swift.ac.uk/xrt_products/TILED_GRB00051/index_1.php.\nThe results of the full analysis of the tiled XRT observations are\navailable at http://www.swift.ac.uk/xrt_products/TILED_GRB00051.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 18795,
  "createdOn": 1451662206000,
  "email": "delia@asdc.asi.it",
  "subject": "GRB 160101A: Swift-XRT afterglow detection",
  "submitter": "Valerio D'Elia at ASDC  <delia@asdc.asi.it>",
  "eventId": "GRB 160101A"
}