{
  "bibcode": "2020GCN.27401....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 (U. of Birmingham), 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 (U. 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 S200316bj (LIGO/VIRGO Collaboration GCN Circ. 27388),\nwhere T0 is the LVC trigger time (2020-03-16T21:57:56.157 UTC).\n\nThe center of the BAT field of view (FOV) at T0 is\nRA = 206.093 deg,\nDEC = 3.456 deg,\nand the roll angle is 90.963 deg.\nThe BAT FOV (>10% partial coding) covers 19.77% of the integrated\nLVC localization probability, and 19.64% 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 astrophysical detections\n(signal-to-noise ratio >~ 5 sigma) are found in the BAT raw light\ncurves with time bins of 64 ms, 1 s, and 1.6 s.\nThe dip and the pulse seen at ~T+50 s is likely due\nto standard calibration run during spacecraft slews.\n\nAssuming a short GRB with a typical spectrum in the BAT energy range\n(i.e., a simple power-law model with a power-law index of -1.32,\nLien & Sakamoto et al. 2016), the 5-sigma upper limit in the 1-s binned\nlight curve corresponds to a flux upper limit (15-350 keV)\nof ~ 4.46 x 10^-7 erg/s/cm^2 for the 100% coded region\n(i.e., for a burst with 0 deg from BAT boresight) and ~ 9.39 x 10^-6\nerg/s/cm2 for the 10% coded region (~56 deg from BAT boresight).\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),\nthese flux upper limits corresponds to a distance of ~ 34.03 Mpc (100%\ncoded)and ~ 7.41 Mpc (10% coded).\n\nNo event data are available in T0 +/- 100 s. The event data\ncollected via the GUANO system (Tohuvavohu et al. 2020, in prep)\nwere not available due to the limited availability of the TDRSS\ncommanding at the time.\n\nBAT retains decreased, but significant, sensitivity to rate increases for\ngamma-ray events outside of its FOV. About 61.67% 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/S200316bj/web/source_public.html",
  "circularId": 27401,
  "createdOn": 1584470703000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "LIGO/Virgo S200316bj: no counterpart candidates in the Swift/BAT observations",
  "submitter": "Amy Lien at GSFC  <amy.y.lien@nasa.gov>",
  "eventId": "LIGO/Virgo S200316bj"
}