TITLE: GCN CIRCULAR NUMBER: 34319 SUBJECT: LIGO/Virgo/KAGRA S230802aq: Upper limits from Fermi-GBM Observations DATE: 23/08/02 20:57:42 GMT FROM: Joshua Wood at NASA/MSFC J. Wood (NASA/MSFC) and J. Mangan (CNRS/IJCLab) report on behalf of the Fermi-GBM Team: For S230802aq (GCN 34314) and using the initial bayestar skymap, Fermi-GBM was observing 59.4% of the localization probability at event time. There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo/KAGRA (LVK) detection of GW trigger S230802aq. 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 LVK localization region is behind the Earth for Fermi, located at an RA=335.9, Dec=25.3 with a radius of 67.6 degrees. We therefore set upper limits on impulsive gamma-ray emission for the GW localization region visible to Fermi at merger time. 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: 1.2 2.1 4.6 1.024 s: 0.3 0.6 1.3 8.192 s: 0.1 0.1 0.2 Assuming the a posteriori mean luminosity distance of 444 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: 4.3 7.0 25. 1.024s: 1.0 2.1 7.1 8.192s: 0.3 0.4 1.3