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GCN Circular 30957

IceCube-211023A - IceCube observation of a high-energy neutrino candidate track-like event
2021-10-23T09:47:02Z (3 years ago)
Dr. Massimiliano Lincetto at Ruhr-Universitaet Bochum <>
The IceCube Collaboration ( reports:

On 2021/10/23 at 08:31:18.31 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 3.2 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: 2021/10/23
Time:  08:31:18.31 UT
RA: +253.30 (+1.05 / -1.08 deg  90% PSF containment) J2000
Dec: -1.72 (+1.16 / -1.11 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.

One gamma-ray source, 4FGL J1653.6-0158, is located within the 90% of the error region, 0.27 deg away from the best-fit position. The source is associated with the pulsar PSR J1653-0158.

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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