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GCN Circular 31120

Subject
IceCube-211123A: Upper limits from Fermi-GBM Observations
Date
2021-11-24T20:42:41Z (2 years ago)
From
Cori Fletcher at USRA <cfletcher@usra.edu>
C. Fletcher (USRA) reports on behalf of the Fermi-GBM team:

For the IceCube high-energy neutrino candidate event IceCube-211123A
(GCN 31110), at the event time Fermi-GBM was observing the reported
neutrino location at:

RA: 265.52 (+3.14 -2.84 deg  90% PSF containment) J2000
Dec: 7.33 (+2.38 -2.48 deg 90% PSF containment) J2000

There was no Fermi-GBM onboard trigger around the event time of the
neutrino candidate. 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 the neutrino candidate time.
From this search, no significant signal was found related
to IceCube-211123A.

We set upper limits on impulsive gamma-ray emission. 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 (in units of 10^-7 erg/s/cm^2):

Timescale   Soft     Normal   Hard
-------------------------------------------
0.128 s:   4.7   7.9   20.
1.024 s:   1.8   3.0   6.5
8.192 s:   0.47 0.88 1.6
These results are preliminary.
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