TITLE:   GCN CIRCULAR
NUMBER:  27791
SUBJECT: IceCube-200523A: Upper limits from Fermi-GBM Observations
DATE:    20/05/23 16:57:34 GMT
FROM:    Joshua Wood at MSFC/Fermi-GBM  <joshua.r.wood@nasa.gov>

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

For the IceCube high-energy neutrino candidate event IceCube-200523A
(GCN 27787), at the event time Fermi-GBM was observing the reported
neutrino location at:

RA: 338.64 (+10.77 -6.07 deg 90% PSF containment) J2000
Dee: 1.75 (+1.84 -3.54 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-200523A.

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:    6.5      9.5      17.
1.024 s:    2.2      2.9      6.1
8.192 s:    0.9      1.3      1.8

These results are preliminary.