TITLE: GCN CIRCULAR NUMBER: 25170 SUBJECT: LIGO/Virgo S190727h: Upper limits from Fermi-GBM Observations DATE: 19/07/27 14:13:25 GMT FROM: C. Michelle Hui at MSFC/Fermi-GBM C. M. Hui(NASA/MSFC) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group For S190727h and using the initial BAYESTAR skymap, Fermi-GBM was observing 65% 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 S190727h (GCN 25164). 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. Part of the LVC localization region is behind the Earth for Fermi, located at RA=288.0, Dec=21.0 with a radius of 67.2 degrees. 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 (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 3.7 5.7 14.0 1.024 s: 1.2 2.8 5.8 8.192 s: 0.6 1.1 1.9 Assuming the median luminosity distance of 2022 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^50 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 3.4 4.5 18.8 1.024 s: 1.1 2.2 7.8 8.192 s: 0.5 0.9 2.5