{
  "bibcode": "2017GCN.20772....1L",
  "body": "A. Y. Lien (GSFC/UMBC), S.D. Barthelmy (NASA/GSFC), D.M. Palmer (LANL),\nT. Sakamoto (AGU), 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 \u001b$B!^\u001b(B 100 s of the\nLIGO event G275697 (LIGO/VIRGO Collaboration GCN Circ. 20763),\nwhere T0 is the LIGO trigger time (2017-02-27T18:57:31.375 UTC).\n\nThe BAT pointing position at T0 is\n\nRA = 284.163 deg,\nDEC = -37.915 deg,\nROLL = 78.846 deg.\n\nThe BAT Field of View (>10% partial coding) covers 8.28% of the integrated\nLIGO localization probability.\n\nNo significant detections (signal-to-noise ratio > 4 sigma) are found\nin the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s, respectively.\nAssuming an on-axis (100% coded) short GRB with a typical spectrum in the BAT\nenergy range (i.e., a simple power-law model with a power-law index of -1.32;\nLien & Sakamoto et al. 2016), the 4-sigma upper limit in the 1-s binned light\ncurve corresponds to a flux upper limit (15-350 keV) of ~ 6.8 x 10^-8 erg/s/cm^2.\nMoreover, so far no event data are found within T0 \u001b$B!^\u001b(B 100 s.\n\nBAT retains decreased, but significant, sensitivity to rate increases for\ngamma-ray events outside of its FOV. About 58.37% 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": 20772,
  "createdOn": 1488262685000,
  "email": "tsakamoto@phys.aoyama.ac.jp",
  "subject": "LIGO/Virgo G275697: Swift/BAT data search",
  "submitter": "Takanori Sakamoto at Aoyama Gakuin U  <tsakamoto@phys.aoyama.ac.jp>",
  "eventId": "LIGO/Virgo G275697"
}