GCN Circular 27022

S. Poolakkil (UAH) reports on behalf of the Fermi-GBM Team and the
GBM-LIGO/Virgo group.

For S200208q and using the bayestar.fits.gz,1 skymap, Fermi-GBM was
observing
95.4% 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 S200208q (GCN 27014
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=306.6, Dec=17.6 with a radius of 67.3 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
Not found
 
 
, 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 norm hard
--------------------------
0.128 s:   7.3  9.9  17.
1.024 s:   2.3  2.9  6.0
8.192 s:   0.6  0.9  2.2

Assuming the median luminosity distance of 2900 Mpc from the GW detection,
we estimate the following intrinsic luminosity upper limits over the 1
keV-10 MeV energy range (in units of 10^50 erg/s):

Timescale  Soft     Normal   Hard
------------------------------------
0.128s:    11.6     13.7    39.8
1.024s:    3.6      4.0     14.0
8.192s:    1.0      1.4     5.1