TITLE: GCN CIRCULAR NUMBER: 25886 SUBJECT: LIGO/Virgo S190930s: Upper limits from Fermi-GBM Observations DATE: 19/09/30 19:52:14 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group For S190930s and using the initial bayestar.fits.gz skymap, Fermi-GBM was observing 62.2% of the localization probability at event time. There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo detection of GW trigger S190930s (GCN 25871). An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around merger time, and also identified no counterpart candidates. We therefore set upper limits on impulsive gamma-ray emission. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV, weighted by GW localization probability (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 5.7 6.6 10. 1.024 s: 1.6 2.2 3.5 8.192 s: 0.6 0.7 1.0 Assuming the median luminosity distance of 752 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^49 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 5.94 6.29 15.8 1.024 s: 1.67 2.10 5.53 8.192 s: 0.62 0.65 1.58