GCN Circular 25385
Subject
LIGO/Virgo S190814bv: Fermi-LAT search for a high-energy gamma-ray counterpart
Date
2019-08-17T18:56:37Z (5 years ago)
From
Masanori Ohno at Hiroshima University <ohno@astro.hiroshima-u.ac.jp>
M. Ohno (Hiroshima Univ.), M. Axelsson (KTH and Stockholm Univ.), F. Longo
(Univ. and INFN Trieste), D. Kocevski (NASA/MSFC), N. Omodei (Stanford
Univ.) and F. Dirirsa (Univ. of Johannesburg) report on behalf of the
Fermi-LAT Collaboration:
We have searched data collected by the Fermi Large Area Telescope (LAT) on
Aug 14, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in
spatial/temporal coincidence with the LIGO/Virgo trigger S190814bv (GCN
25324).
We define "instantaneous coverage" as the integral over the region of the
LIGO
probability map that is within the LAT field of view at a given a time, and
"cumulative
coverage" as the integral of the instantaneous coverage over time.
Fermi-LAT had
instantaneous coverage of the full LIGO probability region at the time of
the trigger
(T0 = 2019-08-14 21:10:39.013 UTC).
We performed a search for a transient counterpart within the observed
region of
the 90% contour of the LIGO map in a fixed time window from T0 to T0 + 10
ks.
No significant sources were found.
We also performed a search which adapted the time interval of the analysis
to the
exposure of each region of the sky, and no additional excesses were found.
Energy flux upper bounds for the fixed time interval between 100 MeV and 1
GeV
for this search vary between 3.1e-10 and 8.5e-10 [erg/cm^2/s].
The Fermi-LAT point of contact for this event is Feraol Dirirsa (
fdirirsa@uj.ac.za).
The Fermi-LAT is a pair conversion telescope designed to cover
the energy band from 20 MeV to greater than 300 GeV
It is the product of an international collaboration between
NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.