GCN Circular 28004
Subject
Fermi-LAT Gamma-ray Observations of IceCube-200620A
Event
Date
2020-06-21T12:27:44Z (6 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
IC200620A neutrino event (GCN 27997) 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 2020-06-20 at 03:03:32.28
UT (T0) with J2000 position RA =162.11 (+0.64 -0.95) deg, Decl. = 11.95
(+0.63 -0.48) deg 90% PSF containment. No cataloged >100 MeV gamma-ray
sources (The Fermi-LAT Collaboration 2019, arXiv:1902.10045) are located
within the 90% IC200620A localization error.
We searched for intermediate (days to years) timescale emission from a
new gamma-ray transient source. Preliminary analysis indicates no
significant (> 5 sigma) new excess emission (> 100 MeV), at the
IC200620A best-fit position. 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 < 1.4e-10 ph cm^-2 s^-1
for ~11-years (2008-08-04 / 2020-06-20 UTC), < 1.7e-8 (< 1.6e-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 these observations the
Fermi-LAT contact persons are S. Garrappa (simone.garrappa at desy.de
<http://desy.de/>) and S. Buson (sara.buson at uni-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.
*