[vsnet-grb-info 24313] LIGO/Virgo S191213g: No counterpart candidates in Fermi-LAT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26412
SUBJECT: LIGO/Virgo S191213g: No counterpart candidates in Fermi-LAT observations   
DATE:    19/12/13 16:18:14 GMT
FROM:    Sara Cutini at INFN  <sara.cutini at pg.infn.it>

S. Cutini (INFN Perugia), N. Omodei (Stanford Univ.), M. Axelsson (KTH & Stockholm Univ,), E. Bissaldi (Politecnico & INFN Bari), D. Kocevski (NASA/MSFC),  F.Longo (University and INFN, Trieste) 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 December 13th, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in 
spatial/temporal coincidence with the LIGO/Virgo trigger S191213g (GCN  26402). 
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 had an instantaneous coverage of 80% of the LIGO probability at the time of the trigger
(T0 = 2019-12-13 04:34:08.142 UTC), and reached 100% cumulative coverage  after 4.5 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 to T0 + 10 ks. 
No significant new sources are 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 ~2e-10 and ~2e-07 [erg/cm^2/s].  
The Fermi-LAT point of contact for this event is  Sara Cutini (sara.cutini at pg.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.