[vsnet-grb-info 24106] LIGO/Virgo S191109d: Upper limits from Fermi-GBM Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26205
SUBJECT: LIGO/Virgo S191109d: Upper limits from Fermi-GBM Observations
DATE:    19/11/09 05:51:52 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

P. Veres (UAH) reports on behalf of the Fermi-GBM Team and the
GBM-LIGO/Virgo group:

For S191109d and using the initial BAYESTAR skymap, Fermi-GBM was observing
87.2% of the localization probability at event time.

There was no Fermi-GBM onboard trigger around the event time of S191109d
(GCN 26202). 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= 320.9, Dec= 12.1 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     normal   hard
--------------------------------------
0.128 s:   6.3      9.5      23
1.024 s:   1.5      2.3      5.5
8.192 s:   0.50     0.76     1.4

Assuming the median luminosity distance of 1810 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     Normal   Hard
------------------------------------
0.128s:    38       52       210
1.024s:    9.2      13       50
8.192s:    3.1      4.1      13