{
  "bibcode": "2017GCN.20746....1S",
  "body": "T. Sakamoto (AGU), S.D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC),\nD.M. Palmer (LANL), A. A. Breeveld (MSSL-UCL), A.P. Beardmore (U. Leicester),\nD.N. Burrows (PSU), S. Campana (INAF-OAB), S.B. Cenko (NASA/GSFC),\nG. Cusumano (INAF-IASF PA), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB),\nV.D'Elia(ASDC), P.A. Evans (U. Leicester), N. Gehrels (NASA/GSFC),\nP. Giommi (ASI), C. Gronwall (PSU), J. A. Kennea (PSU),\nH.A. Krimm (CRESST/GSFC/USRA), N.P.M. Kuin (UCL-MSSL), D. Malesani (DARK/NBI),\nF.E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), B. Mingo (U. Leicester),\nJ.A. Nousek (PSU), S.R. Oates (Uni. of Warwick), P.T. O'Brien (U. Leicester),\nJ.P. Osborne (U. Leicester), C. Pagani (U. Leicester), K.L. Page (U.Leicester),\nM. Perri (ASDC), J.L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU),\nM.H. Siegel (PSU), G. Tagliaferri (INAF-OAB), E. Troja (NASA/GSFC/UMCP)\nreport on behalf of the Swift team:\n\nWe report the search results in the BAT data within T0+/-100 s of the\nLIGO event G275404 (LIGO/VIRGO Collaboration GCN Circ. 20738),\nwhere T0 is the LIGO trigger time (2017-02-25T18:30:21.374023 UTC).\n\nThe BAT pointing position at T0 is\n    RA   = 174.752 deg,\n    DEC  = -37.723 deg,\n    ROLL = 153.273 deg.\nThe BAT Field of View (>0.1 partial coding) covers 18.68% of the integrated\nLIGO localization probability.\n\nNo significant detections (signal-to-noise ratio > 4 sigma) are found\nin the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s, respectively.\nAssuming an on-axis (100% coded) short GRB with a typical spectrum in the BAT\nenergy range (i.e., a simple power-law model with a power-law index of -1.32;\nLien & Sakamoto et al. 2016), the 4-sigma upper limit in the 1-s binned light\ncurve corresponds to a flux upper limit (15-350 keV) of ~ 7.3 x 10^-8 erg/s/cm^2.\n\nBAT retains decreased, but significant, sensitivity to rate increases for\ngamma-ray events outside of its FOV.  About 81.32% of the integrated LIGO\nlocalization probability was outside of the BAT FOV but above the Earth's limb\nfrom Swift's location, and the corresponding flux upper limits for this region\nare within roughly an order of magnitude of those within the FOV.",
  "circularId": 20746,
  "createdOn": 1488078738000,
  "email": "scott@lheamail.gsfc.nasa.gov",
  "subject": "LIGO/Virgo G275404: Swift/BAT data search",
  "submitter": "Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>",
  "eventId": "LIGO/Virgo G275404"
}