GCN Circular 26290
Subject
Fermi-LAT Gamma-ray Observations of IceCube-191122A
Date
2019-11-24T14:17:15Z (5 years ago)
From
Simone Garrappa at DESY <simone.garrappa@desy.de>
S. Garrappa (DESY-Zeuthen) and S. Buson (Univ. of Wuerzburg) on behalf
of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the high-energy
IC191122A neutrino event (GCN 26276) with all-sky survey data from the
Large Area Telescope (LAT), on board the Fermi Gamma-ray Space
Telescope. The IceCube event was detected on 2019-11-22 22:45:10.50 UT
(T0) with J2000 position RA = 27.25 (+1.70, -2.90) deg, Decl. = -0.04
(+1.17, -1.49) deg 90% PSF containment. No cataloged >100 MeV gamma-ray
sources are located within the 90% IC191122A localization error.
We searched for the existence of intermediate (months to years)
timescale emission from a new gamma-ray transient source. Preliminary
analysis indicates no significant (>5sigma) new excess emission (> 100
MeV) within the IC191122A 90% confidence localization. Assuming a
power-law spectrum (photon index = 2.0 fixed) for a point source at the
IceCube best-fit position, the >100 MeV flux upper limit (95%
confidence) is < 1.5e-10 ph cm^-2 s^-1 for ~11-years (2008-08-04 /
2019-11-22 UTC), < 8.4e-9 (< 1.5e-7) ph cm^-2 s^-1 for a 1-month (1-day)
integration time before T0.
Since Fermi normally operates in an all-sky scanning mode, regular
monitoring of this source will continue. For this source the Fermi-LAT
contact person are S. Garrappa (simone.garrappa atdesy.de
<http://desy.de/>) and S. Buson (sara.buson atuni-wuerzburg.de
<http://uni-wuerzburg.de/>). 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.