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GCN Circular 26727

LIGO/Virgo 200112r: No counterpart candidates in Fermi-LAT observations
2020-01-13T09:24:41Z (5 years ago)
Francesco Longo at U of Trieste,INFN Trieste <>
F. Longo (University and INFN, Trieste), D. Kocevski (NASA/MSFC)
and M. Arimoto (Kanazawa Univ.) report on behalf of the Fermi-LAT Collaboration:

We have searched data collected by the Fermi Large Area Telescope (LAT) on
January 12th, 2020, for possible high-energy (E > 100 MeV) gamma-ray emission in
spatial/temporal coincidence with the LIGO/Virgo trigger S200112r (GCN 26715).

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 time,
and "cumulative
coverage" as the integral of the instantaneous coverage over time.
Fermi-LAT was in SAA at the time of the trigger of the event
(T0 =2020-01-12 15:58:38.094 UTC), started to observe the LIGO
probability region around 1.8 ks later with an instantaneous coverage of 30%
and reached 100% cumulative coverage of the LIGO probability after about 10 ks.

We performed a search for a transient counterpart within the observed region of
the 90% contour of LIGO map in a fixed time window from T0 +1.8 ks to
T0 + 10 ks.

Two significant excess (with TS>25) were found.
The first one at R.A., Dec. = 215.8, 32.4 is likely associated with
the known and
currently active source OQ 334, the second one at R.A., Dec. = 57.2,
-27.8 is instead
likely associate with the source PKS 0346���27, also currently active.

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 1.6e-10 and 4.3e-07 [erg/cm^2/s].

The Fermi-LAT point of contact for this event is
F.Longo (

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.
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