TITLE: GCN CIRCULAR NUMBER: 24579 SUBJECT: LIGO/Virgo S190517h: Fermi GBM Observations DATE: 19/05/17 13:41:15 GMT FROM: Adam Goldstein at Fermi-GBM, USRA A. Goldstein (USRA) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group: For S190517h, and using the initial BAYESTAR skymap, Fermi-GBM was observing 28.2% 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 S190517h (GCN 24570). 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 = 270.7 and Dec = -6.7 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 spectral templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV, weighted by the remaining visible GW localization probability (in units of erg/s/cm^2): Timescale soft norm hard -------------------------------------- 0.128 s: 1.9e-07 3.1e-07 5.8e-07 1.024 s: 5.4e-08 8.1e-08 1.9e-07 8.192 s: 9.3e-09 1.5e-08 6.4e-08 Assuming the median luminosity distance of ~2950 Mpc from the GW detection, we estimate intrinsic luminosity upper limits of (0.2-3.1)E50 erg/s for the soft template, (0.2-4.4)E50 erg/s for the normal template, and (1.5-14.)E50 erg/s for the hard template over the 1 keV-10 MeV energy range.