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GCN Circular 24967

Subject
Fermi-LAT Gamma-ray Observations of IceCube-190629A
Date
2019-07-02T14:04:44Z (5 years ago)
From
Sara Buson at GSFC/Fermi <sara.buson@gmail.com>
S. Garrappa (DESY-Zeuthen, DE), S. Ciprini (INFN Roma Tor Vergata, ASI, IT) and S. Buson (Univ. of Wuerzburg, DE; UMBC, USA) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy IC190629A neutrino event (GCN 24910) 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 2019-06-29 19:24:52 UTC (T0) with J2000 position RA = 27.22 (error not provided) deg, Decl. = -84.33 (+4.95 -3.13) deg 90% PSF containment. 

We searched for the existence of intermediate (months to years) timescale emission from a new gamma-ray transient source at the best-fit IC190629A position. Preliminary analysis indicates no significant (>5sigma) new excess emission (0.1 - 300 GeV) at the best-fit IC190629A 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 < 3e-10 ph cm^-2 s^-1 for ~10.9-years (2008-08-04 / 2019-06-20 UTC) and < 7e-9 (< 5e-8) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0.

Several cataloged gamma-ray sources are found within 5 degree from the best-fit IC190629A position. None of these is significantly detected in the 1-month and 1-day scale integration time before T0. Analysing the Fermi-LAT data in the vicinity of IC190629A, we find evidence for a new gamma-ray source, significantly (>5 sigma) detected in the 10.9-years time interval, and also on shorter timescales as reported in ATel #12902. It is positionally consistent with the blazar S5 0532+82, and located 6.5 degrees from the best-fit position of IC-190629A.

Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. For this source the Fermi-LAT contact person are S. Ciprini (stefano.ciprini.asdc at gmail.com) and S. Garrappa (simone.garrappa at desy.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.
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