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GCN Circular 35841

IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
2024-03-01T00:32:04Z (5 months ago)
Marcos Santander at U of Alabama <>
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The IceCube Collaboration ( reports:

On 2024-02-29 at 15:48:21.52 UT IceCube detected a track-like event with a moderate 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 1.336 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: 2024-02-29
Time: 15:48:21.52 UT 
RA: 72.25 (+1.28, -1.26 deg  90% PSF containment) J2000
Dec: +15.79 (+1.08, -0.92 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 is one known Fermi-LAT source (either in the 4FGL-DR4 or 3FHL catalogs) located within the 90% uncertainty region of the event: 4FGL J0445.7+1535, located at RA: 71.44 deg, Dec: 15.60 deg J2000 (0.81 deg away from the best-fit event 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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