GCN Circular 24513
Subject
LIGO/Virgo S190512at: Fermi GBM Observations
Date
2019-05-13T01:19:59Z (6 years ago)
From
Suraj Poolakkil at UAH <sp0076@uah.edu>
S. Poolakkil (UAH) and C.M. Hui (NASA/MSFC) report on behalf of the
Fermi-GBM Team
and the GBM-LIGO/Virgo group:
For S190512at, and using the updated BAYESTAR skymap, Fermi-GBM was
observing 34.7% 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 S190512at (GCN 24503). 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.
Part of the LVC localization region is behind the Earth for Fermi,
located at RA = 308.1 and Dec = -3.6 with a radius of 67.2 degrees.
We therefore set upper limits on impulsive gamma-ray emission. Using the
representative soft, normal, and hard GRB-like spectral templates described
in arXiv:1612.02395, we set the following 3 sigma flux upper limits over
10-1000 keV,
weighted by the remaining visible GW localization probability (in units of
erg/s/cm^2):
Timescale soft norm hard
-----------------------------------------------
0.128 s: 2.4e-07 4.3e-07 1.0e-06
1.024 s: 5.3e-08 1.1e-07 2.5e-07
8.192 s: 2.3e-08 2.3e-08 8.0e-08
Assuming the median luminosity distance of ~1331 Mpc from the GW detection,
we
estimate intrinsic luminosity upper limits of (0.8-7.9)E49 erg/s for the
soft template, (0.7-12.7)E49 erg/s for the normal template, and
(3.9-49.3)E49 erg/s
for the hard template over the 1 keV-10 MeV energy range.