TITLE: GCN CIRCULAR NUMBER: 26461 SUBJECT: LIGO/Virgo S191216ap: Upper limits from Fermi-GBM Observations DATE: 19/12/17 02:19:46 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 S191216ap and using the initial bayestar.fits.gz skymap, Fermi-GBM was observing 99.8% 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 S191216ap (GCN 26454). 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 8.5 16. 1.024 s: 2.1 3.6 5.7 8.192 s: 0.7 1.0 2.0 Assuming the median luminosity distance of 324 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^48 erg/s): Timescale Soft Normal Hard ------------------------------------ 0.128s: 11. 15. 47. 1.024s: 4.0 6.4 17. 8.192s: 1.4 1.8 5.9