GCN Circular 25530
Subject
LIGO/Virgo S190828j: No counterpart candidates in Fermi-LAT observations
Date
2019-08-28T22:43:12Z (5 years ago)
From
Frederic Piron at CNRS/IN2P3/LUPM <piron@in2p3.fr>
F. Piron (CNRS/IN2P3/LUPM), N. Omodei (Stanford Univ.), F.��Longo (Univ.
and INFN Trieste), M. Arimoto (Kanazawa Univ.), D. Kocevski (NASA/MSFC),
M. Axelsson (KTH and Stockholm Univ.) and E. Bissaldi (Politecnico and
INFN Bari)��report on behalf of the Fermi-LAT Collaboration:
We have searched data collected by the Fermi Large Area Telescope (LAT)
on Aug 28, 2019, for possible high-energy (E > 100 MeV) gamma-ray
emission in spatial/temporal coincidence with the LIGO/Virgo trigger
S190828j��(GCN 25497).
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 a null instantaneous coverage of the
LIGO probability region at the time of the trigger (T0 = 2019-08-28
06:34:05.756UTC), and reached ~52%��cumulative coverage after 10 ks.
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 4.3e-10 and 8.5e-8 [erg/cm^2/s].
The Fermi-LAT point of contact for this event is Frederic Piron
(piron@in2p3.fr).
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.