{
  "bibcode": "2019GCN.24146....1V",
  "body": "P. Veres (UAH), C. M. Hui (NASA/MSFC) and A. Goldstein (USRA) report on\nbehalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group:\n\n\n\"At the time of the S190421ar GW trigger (2019-04-21 21:38:56.41 UT), based\non the initial BAYESTAR skymap, Fermi-GBM was observing 78.6% of the\nlocalization probability region.\n\nThere was no Fermi-GBM onboard trigger around the event time of the\nLIGO/Virgo detection (GCN 24141). An automated, blind search for short\ngamma-ray bursts below the onboard triggering threshold in Fermi-GBM also\nidentified no counterpart candidates. The GBM targeted search, the most\nsensitive, coherent search for GRB-like signals, was run for the +/-30 s\ninterval around merger time, and also identified no counterpart candidates.\n\nWe therefore set upper limits on impulsive gamma-ray emission considering\nthe 90% credible region of the GW localization. Using the representative\nsoft, normal, and hard GRB-like spectral templates described in\narXiv:1612.02395, we set the following 3 sigma flux upper limits over\n10-1000 keV (in units of 10^-7 erg/s/cm^2):\n\nTimescale  Soft     Normal   Hard\n------------------------------------\n0.1 s:     4.3-6.6  8.5-11   26-29\n1.0 s:     1.3-2.1  2.7-3.5  7.7-8.6\n10  s:     0.4-0.6  0.8-1.1  2.4-2.6\n\nAssuming the mean luminosity distance of ~2300 Mpc (z=0.42) from the GW\ndetection, we estimate intrinsic luminosity upper limits of (4.1-67)E49\nerg/s for the soft template, (7.1-98)E49 erg/s for the normal template, and\n(3.6-44)E50 erg/s for the hard template over the 1 keV-10 MeV energy range.\"",
  "circularId": 24146,
  "createdOn": 1555960746000,
  "email": "veresp@gmail.com",
  "subject": "LIGO/Virgo S190421ar: Fermi-GBM Observations",
  "submitter": "Peter Veres at UAH  <veresp@gmail.com>",
  "eventId": "LIGO/Virgo S190421ar"
}