[vsnet-grb-info 26431] IceCube-200926B: Upper limits from Fermi-GBM Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28531
SUBJECT: IceCube-200926B: Upper limits from Fermi-GBM Observations
DATE:    20/09/29 19:52:05 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-200926B
(GCN 28509), at the event time Fermi-GBM was observing the reported
neutrino location at:

RA: 184.75 (+3.64 -1.55  deg 90% PSF containment) J2000
Dec: 32.93 (+1.15 -0.91  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-200926B.

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:    7.2      10.      23.
1.024 s:    2.1      3.6      6.5
8.192 s:    0.7      1.0      2.4

These results are preliminary.