[vsnet-grb-info 22921] LIGO/Virgo S190701ah: No counterpart candidates in Fermi-LAT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25020
SUBJECT: LIGO/Virgo S190701ah: No counterpart candidates in Fermi-LAT observations
DATE:    19/07/07 15:35:38 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi at ba.infn.it>

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 July 1, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission
in spatial/temporal coincidence with the LIGO/Virgo trigger S190701ah (GCN 24950).

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 = 2019-07-01 20:33:06.578 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 3.4e-10 and 1.2e-09 [erg/cm^2/s].

The Fermi-LAT point of contact for this event is
Elisabetta Bissaldi (elisabetta.bissaldi at ba.infn.it)."


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.