[vsnet-grb-info 23673] HAWC-190916A: Upper limits from Fermi-GBM Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25772
SUBJECT: HAWC-190916A: Upper limits from Fermi-GBM Observations
DATE:    19/09/17 17:50:53 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 HAWC-190916A, Fermi-GBM was observing the full localization region at event time.

There was no Fermi-GBM onboard trigger around the event time of HAWC-190916A (GCN 25766 and 25768). 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 trigger time, and also identified no counterpart candidates.

We therefore 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:   1.5      2.3      4.9
1.024 s:   0.6      0.9      1.9
8.192 s:   0.2      0.4      0.7