{
  "bibcode": "2017GCN.21665....1P",
  "body": "D. M. Palmer (LANL), S. D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC),\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), S. Emery (UCL-MSSL), P. A. Evans (U. Leicester), \nP. Giommi (ASI), C. Gronwall (PSU), J. A. Kennea (PSU), \nH. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (UCL-MSSL), \nF. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), \nB. Mingo (U. Leicester), J. A. Nousek (PSU), S. R. Oates (Uni. of Warwick), \nP. T. O'Brien (U. Leicester), J. P. Osborne (U. Leicester), \nC. Pagani (U. Leicester), K. L. Page (U.Leicester), M. Perri (ASDC), \nJ. 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\nLVC event G298936 (LIGO/VIRGO Collaboration GCN Circ. 21656), \nwhere T0 is the LVC trigger time (2017-08-23T13:13:58.518 UTC).\n\nThe center of the BAT FOV at T0 is\nRA = 197.526 deg,\nDEC = -23.362 deg,\nROLL = 292.808 deg.\nThe BAT Field of View (>10% partial coding) covers 9.44% of the integrated\nLVC localization probability.\n\nWithin T0 +/- 100 s, no significant detections (signal-to-noise ratio >~ 5 sigma) \nare found in the BAT raw light curves with time bins of 1 s and 1.6 s. There is \na 5.1 sigma signal at ~T-30 s in the 64-ms binned raw light curve. However, because \nno significant detections are found in the image domain, we believe this spike is \nunlikely to be an astrophysical source in the BAT FOV. Assuming an on-axis (100% \ncoded) short GRB with a typical spectrum in the BAT energy range (i.e., a simple \npower-law model with a power-law index of -1.32, Lien & Sakamoto et al. 2016), \nthe 5-sigma upper limit in the 1-s binned light curve corresponds to a flux upper \nlimit (15-350 keV) of ~ 7.74 x 10^-8 erg/s/cm^2.\n\nThere are event data available from T+46.9 s to T+50.0 s. No detections above \n~ 5 sigma are found in the event data analysis.\n\nBAT retains decreased, but significant, sensitivity to rate increases for\ngamma-ray events outside of its FOV. About 38.31% of the integrated LVC\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": 21665,
  "createdOn": 1503522208000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "LIGO/Virgo G298936: Swift/BAT data search",
  "submitter": "Amy Lien at GSFC/Swift  <amy.y.lien@nasa.gov>",
  "eventId": "LIGO/Virgo G298936"
}