GCN Circular 31546
Subject
Fermi-LAT Gamma-ray Observations of IceCube-220202A
Date
2022-02-03T20:09:52Z (3 years ago)
From
Simone Garrappa at DESY <simone.garrappa@desy.de>
S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and J.
Sinapius (DESY-Zeuthen) on behalf of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the high-energy
IC220202A neutrino event (GCN 31543) 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 2022-02-02 11:48:38.59 UTC
(T0) with J2000 position RA = 21.36 (+1.10, -0.77) deg, Decl. = -3.88
(+0.42, -0.64) deg 90% PSF containment. No cataloged gamma-ray sources
are found within the 90% IC220202A localization error (The Fourth
Fermi-LAT catalog DR3; The Fermi-LAT collaboration 2022, arXiv:2201.11184).
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) at the the IC220202A best-fit position. Assuming a power-law
spectrum (photon index = 2.0 fixed) for a point source at the IC220202A
best-fit position, the >100 MeV flux upper limit (95% confidence) is <
2.4-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 / 2022-02-02 UTC), <
3.7e-9 (< 5.7e-8) 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 these observations the
Fermi-LAT contact persons are S. Garrappa (simone.garrappa at desy.de)
and S. Buson (sara.buson at 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.