[vsnet-grb-info 26828] IceCube-201120A: Upper limits from Fermi-GBM Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28931
SUBJECT: IceCube-201120A: Upper limits from Fermi-GBM Observations
DATE:    20/11/20 22:06:10 GMT
FROM:    Joshua Wood at MSFC/Fermi-GBM  <joshua.r.wood at nasa.gov>

J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM team:

For the IceCube high-energy neutrino candidate event IceCube-201120A
(GCN 28927), at the event time Fermi-GBM was observing the reported
neutrino location at:

RA: 307.53 (+5.34 -5.59 deg 90% PSF containment) J2000
Dec: 40.77 (+4.97 -2.80 deg 90% PSF containment) J2000

A Fermi-GBM onboard GRB trigger (627557935 / 201120402) occurred
around 6 minutes prior to the event time of the neutrino candidate.
However, we estimate that the spatial localization of this trigger
only has a 20% chance of association with the neutrino event. It is
likely unrelated. 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-201120A.

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:    10.      16.      29.
1.024 s:    2.1      3.7      7.3
8.192 s:    0.7      0.9      2.0

These results are preliminary.