{
  "bibcode": "2019GCN.26453....1L",
  "body": "A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (NASA/GSFC),\nD. M. Palmer (LANL), T. Sakamoto (AGU),\nA. P. Beardmore (U. Leicester), M. G. Bernardini (INAF-OAB),\nA. A. Breeveld (MSSL-UCL), D. N. Burrows (PSU),\nS. 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 (ASI-ASDC), S. Emery (UCL-MSSL),\nP. A. Evans (U. Leicester), P. Giommi (ASI), C. Gronwall (PSU),\nD. Hartmann (Clemson U.), J. A. Kennea (PSU),\nN. Klingler (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. J. Page (UCL-MSSL), M. Perri (ASDC),\nJ. L. Racusin (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU),\nM. H. Siegel (PSU), G. Tagliaferri (INAF-OAB), A. Tohuvavohu (Toronto),\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 S191215w (LIGO/VIRGO Collaboration GCN Circ. 26441),\nwhere T0 is the LVC trigger time (2019-12-15T22:30:52.333 UTC).\n\nThe center of the BAT field of view (FOV) at T0 is\nRA = 79.194 deg,\nDEC = -7.503 deg,\nand the roll angle is 167.963 deg.\nThe BAT FOV (>10% partial coding) covers 18.28% of the integrated\nLVC localization probability, and 17.80% of the galaxy convolved\nprobability (Evans et al. 2016). Note that the sensitivity in the BAT FOV\nchanges with the partial coding fraction. Please see the BAT FOV figure\nin the summary page (link below) for the specific location of the LVC\nregion relative to the BAT FOV.\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 ~ 7.70 x 10^-8 erg/s/cm^2.\nAssuming a luminosity of ~ 2 x 10^47 erg/s (similar to GW170817)\nand an average Epeak of ~ 400 keV for short GRBs (Bhat et al. 2016),\nthis flux upper limit corresponds to a distance of ~ 81.91 Mpc.\n\nNo event data are available around T0 +/- 100 s.\n\nBAT retains decreased, but significant, sensitivity to rate increases for\ngamma-ray events outside of its FOV. About 77.71% 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/S191215w/web/source_public.html",
  "circularId": 26453,
  "createdOn": 1576519365000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "LIGO/Virgo S191215w: no counterpart candidates in the Swift/BAT observations",
  "submitter": "Amy Lien at GSFC  <amy.y.lien@nasa.gov>",
  "eventId": "LIGO/Virgo S191215w"
}