TITLE: GCN CIRCULAR NUMBER: 25016 SUBJECT: LIGO/Virgo S190706ai: Upper limits from Fermi-GBM Observations DATE: 19/07/07 12:12:45 GMT FROM: Rachel Hamburg at UAH R. Hamburg (UAH) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group: For the LIGO/Virgo detection of GW trigger S190706ai (GCN 24998) and using the initial BAYESTAR skymap, Fermi-GBM was observing 62.0% of the localization probability at event time. There was no Fermi-GBM onboard trigger around the event time of S190706ai. 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 = 170.4 and Dec = -20.2 with a radius of 67.5 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, weighted by GW localization probability, (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard -------------------------------------- 0.1 s: 5.7 7.5 13. 1.0 s: 1.5 2.2 3.9 10. s: 0.5 0.5 0.9 Assuming the median luminosity distance of 5725 Mpc (z=0.881) from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^51 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.1 s: 3.6 4.0 11.7 1.0 s: 1.0 1.2 3.5 10 s: 0.3 0.3 0.8