GCN Circular 25807
Subject
IceCube-190922A: Upper limits from Fermi-GBM Observations
Date
2019-09-23T05:27:26Z (6 years ago)
From
Eric Burns at GSFC <erickayserburns@gmail.com>
E. Burns (NASA/GSFC) reports on behalf of the Fermi-GBM Team:
For the IceCube high-energy neutrino candidate event 190922A (GCN 25802),
at the event time Fermi-GBM was observing about half the reported neutrino
probability map of:
RA: 167.43 (+ 3.40 - 2.63 deg 90% PSF containment) J2000
Dec: -22.39 (+ 2.88 - 2.89 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-190922A. Over the 1 minute search interval the
Earth-occulted region for Fermi shifted by about 4 degrees, resulting in
time-varying exposure to the neutrino localization.
We set upper limits on impulsive gamma-ray emission for the fraction of
localization region observed as a function of time. Using the
representative soft, normal, and hard GRB-like templates
(arXiv:1612.02395), we report the following 3 sigma flux upper limits over
10-1000 keV (in units of 10^-7 erg/s/cm^2):
Timescale soft norm hard
--------------------------------------
0.128 s: 3.8 6.3 13.
1.024 s: 1.0 1.8 3.7
8.192 s: 0.3 3.9 1.0