TITLE: GCN CIRCULAR NUMBER: 26645 SUBJECT: LIGO/Virgo S200105ae: Upper limits from Fermi-GBM Observations DATE: 20/01/06 20:30:43 GMT FROM: Peter Veres at UAH P. Veres (UAH) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group For S200105ae and using the latest BAYESTAR skymap, Fermi-GBM was observing 82.3% 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 S200105ae (GCN Circ. 26640). 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=255.8, Dec=22.4 with a radius of 67.4 degrees. We therefore set upper limits on impulsive gamma-ray emission for the LVC 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: 4.0 6.3 11 1.024 s: 1.1 1.8 4.4 8.192 s: 0.40 0.63 1.3 Assuming the median luminosity distance of 265 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: 5.1 7.5 21 1.024s: 1.4 2.1 8.6 8.192s: 0.51 0.75 2.5