{
  "bibcode": "2019GCN.26557....1S",
  "body": "T. Sakamoto (AGU), S. D. Barthelmy (NASA/GSFC),\nA. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL)\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 S191222n (LIGO/VIRGO Collaboration GCN Circ. 26543),\nwhere T0 is the LVC trigger time (2019-12-22T03:35:37.119 UTC).\n\nThe center of the BAT field of view (FOV) at T0 is\nRA = 243.449 deg,\nDEC = 65.736 deg,\nand the roll angle is 151.289 deg.\nThe BAT FOV (>10% partial coding) covers 0.04% of the integrated\nLVC localization probability, and 0.04% 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 curves\nwith time bins of 64 ms, 1 s, and 1.6 s. The dip and pulse seen in the\nlight curves around T0+190 s is due to on-board calibration process\nduring spacecraft slews.\n\nAssuming an on-axis (100% coded) short GRB with a typical spectrum in the\nBAT energy range (i.e., a simple power-law model with a power-law index\nof -1.32, Lien & Sakamoto et al. 2016), the 5-sigma upper limit in the\n1-s binned light curve corresponds to a flux upper limit (15-350 keV)\nof ~ 7.80 x 10^-8 erg/s/cm^2. Assuming a luminosity of ~ 2 x 10^47 erg/s\n(similar to GW170817)and an average Epeak of ~ 400 keV for short GRBs\n(Bhat et al. 2016), this flux upper limit corresponds to a distance\nof ~ 81.37 Mpc.\n\nNo event data are available within T0 +/- 100 s at this time.\n\nBAT retains decreased, but significant, sensitivity to rate increases for\ngamma-ray events outside of its FOV. About 86.58% 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/S191222n/web/source_public.html",
  "circularId": 26557,
  "createdOn": 1577033873000,
  "email": "amy.y.lien@nasa.gov",
  "subject": "LIGO/Virgo S191222n: no counterpart candidates in the Swift/BAT observations",
  "submitter": "Amy Lien at GSFC  <amy.y.lien@nasa.gov>",
  "eventId": "LIGO/Virgo S191222n"
}