[vsnet-grb-info 24523] IceCube-191231A: Upper limits from Fermi-GBM Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26622
SUBJECT: IceCube-191231A: Upper limits from Fermi-GBM Observations
DATE:    19/12/31 23:05:00 GMT
FROM:    C. Michelle Hui at MSFC/Fermi-GBM  <c.m.hui at nasa.gov>

C. M. Hui (MSFC) reports on behalf of the Fermi-GBM team:

For the IceCube high-energy neutrino candidate event 191231A (GCN 26620), at the event time Fermi-GBM was observing the reported neutrino location at:

RA: 46.36 (+4.27 -3.47 deg 90% PSF containment) J2000
Dec: 20.42 (+2.11 -2.80 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-191231A.

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     10.      19. 
1.024 s:      1.7      2.6      4.5 
8.192 s:      0.3      0.6      1.4