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GCN Circular 30026

IceCube-210516A - IceCube observation of a high-energy neutrino candidate track-like event
2021-05-16T16:36:59Z (3 years ago)
Marcos Santander at U. Alabama/IceCube <>
The IceCube Collaboration ( reports:

On 16 May 2021 at 14:38:20.34 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 3.1 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: 16 May 2021
Time:  14:38:20.34 UT
RA: 91.76 (+1.05  -0.97 deg  90% PSF containment) J2000
Dec: +9.52 ( +0.50 -0.58 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 or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J0608.6+1149 at RA: 92.17 deg, Dec: 11.83 deg J2000 (2.34 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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