GCN Circular 26194
Subject
LIGO/Virgo S191105e: No counterpart candidates in Fermi-LAT observations
Date
2019-11-07T06:17:36Z (5 years ago)
From
Magnus Axelsson at Stockholm U. <magaxe@kth.se>
M. Axelsson (KTH and Stockholm Univ.), N. Omodei (Stanford Univ.), D. Kocevski (NASA/MSFC), F. Longo (Univ. and INFN Trieste), E. Bissaldi (Politecnico and INFN Bari) and M. Moss (GWU) report on behalf of the Fermi-LAT Collaboration:
We have searched data collected by the Fermi Large Area Telescope (LAT) on Nov 05, 2019, for possible high-energy (E > 100 MeV) gamma-ray emission in spatial/temporal coincidence with the LIGO/Virgo trigger S191105e (GCN 26182).
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 ~20% of the LIGO probability region at the time of the trigger (T0 = 2019-11-05 14:35:21.933 UTC) and reached ~100% cumulative coverage at approximately T0 + 3 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. One significant excess (with TS>25) was found at R.A., Dec. = 342.2, -12.9, but it is likely associated with the known source RBS 1899 (lies within the 90% uncertainty region).
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 between 100 MeV and 1 GeV for the fixed time interval of this search vary between 1.4e-10 and 1.3e-9 [erg/cm^2/s].
The Fermi-LAT point of contact for this event is Michael Moss (michaelmoss@gwmail.gwu.edu).
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.