GCN Circular 24605

S. Poolakkil (UAH) and R. Hamburg (UAH) report on behalf of the
Fermi-GBM Team and the GBM-LIGO/Virgo group:

For S190519bj, and using the initial BAYESTAR skymap, Fermi-GBM was
observing 32.0% 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 S190519bj (GCN 24598
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 = 53.1 and Dec = 15.4 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:   1.3e-07  2.1e-07  4.6e-07
1.024 s:   3.9e-08  6.2e-08  1.4e-07
8.192 s:   1.4e-08  1.6e-08  3.8e-08

Assuming the median luminosity distance of ~3154 Mpc from the GW detection,
we estimate intrinsic luminosity upper limits of (2.6-24.3)E49 erg/s for the
soft template, (2.5-34.0)E49 erg/s for the normal template, and
(1.0-12.6)E50 erg/s for the hard template over the 1 keV-10 MeV energy
range.