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GCN Circular 26185

Subject
LIGO/Virgo S191105e: Upper limits from Fermi-GBM Observations
Date
2019-11-06T18:57:48Z (5 years ago)
From
Adam Goldstein at Fermi-GBM, USRA <adam.michael.goldstein@gmail.com>
A. Goldstein (USRA) reports on behalf of the Fermi-GBM Team and the
GBM-LIGO/Virgo group

For S191105e and using the initial BAYESTAR skymap, Fermi-GBM was observing
77.5% of the localization probability at event time.

There was no Fermi-GBM onboard trigger around the event time of S191105e
(GCN Circ. 26182). 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=315.6, Dec=21.5 with a radius of 67.5 degrees. We therefore set upper
limits on impulsive gamma-ray emission for the LVC localization region
visible to GBM 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     norm     hard
--------------------------------------
0.128 s:   4.1      6.9      14.
1.024 s:   1.3      2.1      4.7
8.192 s:   0.3      0.6      1.6

Assuming the median luminosity distance of 1168 Mpc from the GW detection,
we estimate the following intrinsic luminosity upper limits over the 1
keV-10 MeV energy range (in units of 10^49 erg/s):

Timescale  soft     norm     hard
--------------------------------------
0.128 s:   10.      16.      53.
1.024 s:   3.3      4.8      18.
8.192 s:   0.8      1.4      6.1
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