GCN Circular 24579

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
Not found
 
 
). 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
Not found
 
 
, 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.