TITLE: GCN CIRCULAR NUMBER: 24112 SUBJECT: LIGO/Virgo S190412m: Fermi-GBM Observations DATE: 19/04/12 18:52:52 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 S190412m, and using the initial BAYESTAR skymap, Fermi-GBM was observing 99.8% of the localization probability region at event time. There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo detection of a GW trigger (GCN 24098). 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 considering the 90% credible region of the GW localization. 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 (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------ 0.1 s: 4.7-5.7 9.1-10 25-27 1.0 s: 1.5-1.8 2.8-3.2 7.4-7.9 10 s: 0.5-0.6 0.9-1.0 2.3-2.4 Assuming the mean luminosity distance of 812 Mpc from the GW detection, we estimate intrinsic luminosity upper limits of (0.6-6.9)E49 erg/s for the soft template, (1.0-11)E49 erg/s for the normal template, and (4.2-50)E49 erg/s for the hard template over the 1 keV-10 MeV energy range.