GCN Circular 26461
Subject
LIGO/Virgo S191216ap: Upper limits from Fermi-GBM Observations
Date
2019-12-17T02:19:46Z (5 years ago)
From
Joshua Wood at MSFC/Fermi-GBM <joshua.r.wood@nasa.gov>
J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group
For S191216ap and using the initial bayestar.fits.gz skymap, Fermi-GBM was observing 99.8% of the localization probability at event time.
There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo detection of GW trigger S191216ap (GCN 26454). 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 merger 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, weighted by GW localization probability (in units of 10^-7 erg/s/cm^2):
Timescale Soft Normal Hard
------------------------------------
0.128 s: 5.7 8.5 16.
1.024 s: 2.1 3.6 5.7
8.192 s: 0.7 1.0 2.0
Assuming the median luminosity distance of 324 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^48 erg/s):
Timescale Soft Normal Hard
------------------------------------
0.128s: 11. 15. 47.
1.024s: 4.0 6.4 17.
8.192s: 1.4 1.8 5.9