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GCN Circular 34276

IceCube-230727A - IceCube observation of a high-energy neutrino candidate track-like event
2023-07-27T20:09:11Z (a year ago)
Erik Blaufuss at University of Maryland, College Park <>
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The IceCube Collaboration ( reports:

On 2023-07-27 at 16:05:39.63 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream.  The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 3.384 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.

After the initial automated alert (, more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2023-07-27
Time:  16:05:39.63 UT
RA: 33.66 (+1.16, -0.77 deg  90% PSF containment) J2000
Dec: 7.63 (+0.70, -0.64 deg 90% PSF containment) J2000

We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

There are no Fermi 4FGL-DR3 or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J0219.5+0724 at RA: 34.89 deg, Dec: 7.41 deg (1.25 deg away from the best-fit alert position).

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at

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