{
  "bibcode": "2016GCN.19464....1P",
  "body": "K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A.\nD'Ai (INAF-IASFPA), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), J.A.\nKennea (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester)\nand P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:\n\nSwift-XRT has conducted further observations of the field of the\nFermi/LAT-detected burst GRB 160521B (Axelsson et al. GCN Circ. 19444).\nThe observations now extend from T0+41.9 ks to T0+346.3 ks. The source\npreviously reported by Page et al. (GCN Circ. 19448), \"Source 1\", is\nfading with 3-sigma significance, and is therefore likely the GRB\nafterglow.  The position of this source is RA, Dec=147.6665, +79.0305\nwhich is equivalent to:\n\nRA (J2000): 09:50:39.96\nDec(J2000): +79:01:49.7\n\nwith an uncertainty of 4.2 arcsec (radius, 90% confidence).  This\nposition is 5.9 arcmin from the Fermi/LAT position. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=0.7 (+0.7, -0.4).\n\nThe results of the XRT-team automatic analysis of the likely afterglow\nare at http://www.swift.ac.uk/ToO_GRBs/00020615/index_1.php.\nThe results of the full analysis of the XRT observations are available\nat http://www.swift.ac.uk/ToO_GRBs/00020615.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 19464,
  "createdOn": 1464203531000,
  "email": "andrea.melandri@brera.inaf.it",
  "subject": "GRB 160521B: Swift-XRT afterglow detection",
  "submitter": "Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>",
  "eventId": "GRB 160521B"
}