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GCN Circular 34952

Fermi-LAT gamma-ray observations of IceCube-231103A
2023-11-06T11:48:23Z (7 months ago)
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C. Bartolini (INFN Bari), S. Buson (Uni Wuerzburg), S. Garrappa (Weizmann Institute of Science), and J. Sinapius (DESY) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the IC231103A  high-energy neutrino event (GCN 34933) 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 2023-11-03 at 09:17:35.29 UT (T0) with J2000 position RA =  105.67 (+3.15, -2.94) deg, Decl. = +47.85 (+1.95, -1.78) deg (90% PSF containment).  According to the fourth Fermi LAT source catalog (4FGL-DR4), there are several 4FGL-DR4 cataloged gamma-ray (>100 MeV; The Fermi-LAT collaboration 2022, ApJS, 260, 53) sources in the 90% IC231103A uncertainty localization region. Based on a preliminary analysis of the LAT data over a month and day timescale prior T0, these objects are not significantly detected at gamma rays.

We searched for intermediate (days to years) timescale emission from a new gamma-ray source. Preliminary analysis indicates no significant (> 5 sigma) new excess emission (> 100 MeV) at the IC231103A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC231103A best-fit position, the >100 MeV flux upper limit (95% confidence) is <4.3e-10 ph cm^-2 s^-1 for ~15-years (2008-08-04 to 2023-11-03 UTC), and < 1.3e-8 (<7.2 e-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 region will continue. For these observations the Fermi-LAT contact persons are S. Garrappa (simone.garrappa at, C. Bartolini (chiara.bartolini at, S. Buson (sara.buson at and J. Sinapius (jonas.sinapius at

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.
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