{
  "bibcode": "2019GCN.24646....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), 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 S190521g (LIGO/VIRGO Collaboration GCN Circ. 24621),\nwhere T0 is the LVC trigger time (2019-05-21T03:02:29.447 UTC).\n\nThe center of the BAT FOV at T0 is\nRA = 169.185 deg,\nDEC = 44.211 deg,\nand the ROLL angle is 302.639 deg.\nThe BAT Field of View (>10% partial coding) covers 47.64% of the integrated\nLVC localization probability, and 46.16% 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 64 ms,\n1 s, and 1.6 s. Assuming an on-axis (100% coded) short GRB with a typical\nspectrum in the BAT energy range (i.e., a simple power-law model with a\npower-law index of -1.32, Lien & Sakamoto et al. 2016), the 5-sigma upper\nlimit in the 1-s binned light curve corresponds to a flux upper\nlimit (15-350 keV) of ~ 7.04 x 10^-8 erg/s/cm^2.\n\nEvent data are available from T0-91.427 to T0-88.355. No significant\ndetections are found in the 15-350 keV image made using the whole event\ndata duration.\n\nBAT retains decreased, but significant, sensitivity to rate increases for\ngamma-ray events outside of its FOV. About 41.08% 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/S190521g/web/source.html",
  "circularId": 24646,
  "createdOn": 1558473480000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "LIGO/Virgo S190521g: Swift/BAT Counterpart Search",
  "submitter": "Amy Lien at GSFC  <amy.y.lien@nasa.gov>",
  "eventId": "LIGO/Virgo S190521g"
}