{
  "bibcode": "2019GCN.26238....1E",
  "body": "P.A. Evans (U. Leicester), K.L. Page (U.Leicester), J.A. Kennea (PSU),\nA. Tohuvavohu (U. Toronto), S.D. Barthelmy (NASA/GSFC), A.P. Beardmore\n(U. Leicester), M.G. Bernardini (INAF-OAB), A.A. Breeveld (UCL-MSSL),\nP. Brown (TAMU), D.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko\n(NASA/GSFC), G. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P.\nD'Avanzo (INAF-OAB), V. D'Elia(ASDC), S.W.K. Emery (UCL-MSSL), P.\nGiommi (ASI), C. Gronwall (PSU), D. Hartmann (U. Clemson), H.A. Krimm\n(CRESST/GSFC/USRA), N.J. Klingler (PSU), N.P.M. Kuin (UCL-MSSL), A.Y.\nLien (GSFC/UMBC), F.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),\nJ.A. Nousek (PSU), S.R. Oates (U. Warwick), P.T. O'Brien (U.\nLeicester), J.P. Osborne (U. Leicester), C. Pagani (U. Leicester),\nM.J.Page (UCL-MSSL), D.M. Palmer (LANL), M. Perri (ASDC), J.L. Racusin\n(NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU), M.H. Siegel (PSU), G.\nTagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP) report on behalf of\nthe Swift team:\n\nSwift has carried out 449 observations of the LVC error region for the\nGW trigger S191110af, using the 'cWB' GW localisation map. Because this\nwas a 'burst' pipeline trigger with a high frequency, observations were\nweighted towards the Galactic plane.The observations currently span\nfrom 10 ks to 88 ks after the LVC trigger, and the XRT has covered 53.5\ndegrees^2 on the sky (corrected for overlaps). This covers 0.441% of\nthe probability in the 'cWB' skymap, and 16% after weighting towards\nthe Galactic plane is accounted for.\n\nWe have detected 11 X-ray sources. Each source is assigned a rank of\n1-4 which describes how likely it is to be related to the GW trigger,\nwith 1 being the most likely and 4 being the least likely. The ranks\nare described at https://www.swift.ac.uk/ranks.php.\n\nWe note that a number of GCN/COUNTERPART notices were issued with ranks\n1 or 2; these also all had the WARN_FLAG field set to 1. These were\nspurious sources caused by stray light from a bright X-ray source\noutside of the nominal field of view. Counterpart notices are\nautomatically produced before any human vetting of the sources has been\ncarried out.\n\nAfter vetting, we have found:\n\n  * 0 sources of rank 1\n  * 0 sources of rank 2\n  * 5 sources of rank 3\n  * 6 sources of rank 4\n\nFor all flux conversions and comparisons with catalogues and upper\nlimits from other missions, we assumed a power-law spectrum with\nNH=3x10^20 cm^-2, and photon index (Gamma)=1.7\n\nThe results of the XRT automated analysis are online at\nhttps://www.swift.ac.uk/LVC/S191110af\n\nThis circular is an official product of the Swift XRT team.",
  "circularId": 26238,
  "createdOn": 1573546316000,
  "email": "pae9@leicester.ac.uk",
  "subject": "LIGO/Virgo S191110af: Swift XRT observations, no secure afterglow found",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "LIGO/Virgo S191110af"
}