GCN Circular 28220
Subject
Fermi-LAT Gamma-ray Observations of IceCube-200806A
Event
Date
2020-08-07T15:02:22Z (6 years ago)
From
Sara Buson at GSFC/Fermi <sara.buson@gmail.com>
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 IC200806A neutrino event (GCN 28210) 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 2020-08-06 at 13:50:56.43 UT (T0) with J2000 position RA = 157.25 (+1.21, -0.89) deg, Decl. = 47.75 (+0.65, -0.64) deg 90% PSF containment. No cataloged >100 MeV gamma-ray sources (The Fourth Fermi-LAT catalog; The Fermi-LAT collaboration 2020, ApJS, 247, 33) are located within the 90% IC200806A 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 IC200806A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC200806A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 1.5e-10 ph cm^-2 s^-1 for ~12-years (2008-08-04 / 2020-08-06 UTC), < 3.6e-9 (< 1e-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) 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.