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GCN Circular 27255

Fermi-LAT Gamma-ray Observations of IceCube-200227A
2020-02-28T14:12:03Z (4 years ago)
Sara Buson at GSFC/Fermi <>
S. Buson (Univ. of Wuerzburg) and S. Garrappa (DESY-Zeuthen) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy IC200227A neutrino event (GCN 27235) 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 2020-02-27 05:36:31.50 UT (T0) with J2000 position RA = 348.26 deg, Decl. = 21.32 deg (30.80 arcmin 90% PSF containment - statistical). No cataloged >100 MeV gamma-ray sources are located within the 90% IC200227A 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 IC200227A 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 < 1e-9 ph cm^-2 s^-1 for ~11-years (2008-08-04 / 2020-02-27 UTC), < 7e-9 (< 5e-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 this source the Fermi-LAT contact persons are S. Garrappa (simone.garrappa at and S. Buson (sara.buson 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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