{
  "bibcode": "2019GCN.24255....1B",
  "body": "S. D. Barthelmy (NASA/GSFC), A. Y. Lien (GSFC/UMBC),\nD. M. Palmer (LANL), T. Sakamoto (AGU),\nA. 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),\nP. D'Avanzo (INAF-OAB), V. D'Elia(ASDC), S. Emery (UCL-MSSL),\nP. A. Evans (U. Leicester), P. Giommi (ASI), C. Gronwall (PSU),\nD. Hartmann (Clemson U.), J. A. Kennea (PSU), H. A. Krimm (NSF),\nN. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC),\nA. Melandri (INAF-OAB), B. Mingo (U. Leicester), J. A. Nousek (PSU),\nS. R. Oates (Uni. of Warwick), P. T. O'Brien (U. Leicester),\nJ. P. Osborne (U. Leicester), C. Pagani (U. Leicester),\nK. 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), A. Tohuvavohu (PSU),\nE. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team:\n\nWe report the search results in the BAT data within T0 +/- 100 s of the\nLVC event S190426c (LIGO/VIRGO Collaboration GCN Circ. 24237),\nwhere T0 is the LVC trigger time (2019-04-26T15:21:55.337 UTC).\n\nThe center of the BAT field of view (FOV) at T0 is\nRA = 255.327 deg,\nDEC = -7.000 deg,\nROLL = 77.470 deg.\nThe BAT FOV (>10% partial coding) covers 5.22% of the integrated\nLVC localization probability, and 6.39% of the galaxy convolved\nprobability (Evans et al. 2016).\n\nWithin T0 +/- 100 s, no significant detections (signal-to-noise ratio\n>~ 5 sigma) are found in the BAT raw light curves with time bins of\n64 ms, 1 s, and 1.6 s. Assuming an on-axis (100% coded) short GRB with a\ntypical spectrum in the BAT energy range (i.e., a simple power-law model\nwith a power-law index of -1.32, Lien & Sakamoto et al. 2016), the 5-sigma\nupper limit in the 1-s binned light curve corresponds to a flux upper\nlimit (15-350 keV) of ~ 8.10 x 10^-8 erg/s/cm^2.\n\nNo event data are available at this point.\n\nBAT retains decreased, but significant, sensitivity to rate increases for\ngamma-ray events outside of its FOV. About 94.56% of the integrated LVC\nlocalization probability was outside of the BAT FOV but above the\nEarth's limb from Swift's location, and the corresponding flux upper limits\nfor this region are within roughly an order of magnitude higher than those\nwithin the FOV.\n\nThe results of the BAT analysis are available at\nhttps://swift.gsfc.nasa.gov/results/BATbursts/team_web/S190426c/web/source.html",
  "circularId": 24255,
  "createdOn": 1556327538000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "LIGO/Virgo S190426c: Swift/BAT Counterpart Search",
  "submitter": "Amy Lien at GSFC  <amy.y.lien@nasa.gov>",
  "eventId": "LIGO/Virgo S190426c"
}