{
  "bibcode": "2017GCN.20830....1D",
  "body": "V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU),\nD.N. Burrows (PSU), A. Cholden-Brown (PSU), J.P. Osborne (U.\nLeicester), K.L. Page (U. Leicester), B. Mingo (U. Leicester), A.\nMelandri (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of\nthe Swift-XRT team:\n\nSwift-XRT has performed follow-up observations of the\nFermi/LAT-detected burst GRB 170306B in a series of observations tiled\non the sky. The total exposure time is 4.5 ks, distributed over 8\ntiles; the maximum exposure at a single sky location was 1.4 ks. The\ndata were collected between T0+17.4 ks and T0+29.9 ks, and are entirely\nin Photon Counting (PC) mode. \n\nNo uncatalogued X-ray sources have been detected. The 3-sigma upper\nlimit in the field (not including the regions where the tiles overlap)\nranges from ~0.007 to ~0.021 ct s^-1, corresponding to a 0.3-10 keV\nobserved flux of 2.9e-13 to 8.5e-13 erg cm^-2 s^-1 (assuming a typical\nGRB spectrum).\n\nFour previously-catalogued X-ray sources have been detected, however\ntheir status as catalogued objects makes them unlikely to be the\nafterglow.\n\nThe results of the XRT-team automatic analysis of the tiled XRT\nobservations, including a position-specific upper limit calculator, are\navailable at http://www.swift.ac.uk/xrt_products/TILED_GRB00065.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 20830,
  "createdOn": 1488886324000,
  "email": "andrea.melandri@brera.inaf.it",
  "subject": "GRB 170306B: Swift-XRT observations",
  "submitter": "Andrea Melandri at INAF-OAB  <andrea.melandri@brera.inaf.it>",
  "eventId": "GRB 170306B"
}