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GCN Circular 33337

IceCube-230217A - IceCube observation of a high-energy neutrino candidate track-like event
2023-02-17T21:55:47Z (a year ago)
Marcos Santander at U. Alabama/IceCube <>
The IceCube Collaboration ( reports:

On 2023-02-17 at 20:49:43.4 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 1.877 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: 2023-02-17
Time:  20:49:43.4 UT
RA: 124.54 (+1.67/-3.27  deg  90% PSF containment) J2000
Dec: 20.74 (+2.14/-2.46 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.

Two gamma-ray sources listed in the 4FGL-DR3 Fermi-LAT catalog are located within the 90% error region of the candidate neutrino event. The sources are 4FGL J0816.9+2050 and 4FGL 4FGL J0817.1+1955, and are located 0.3 and 0.85 deg away from the best-fit position, respectively. The source 4FGL J0816.9+2050 is also listed in the Fermi 3FHL catalog as 3FHL J0816.9+2050.

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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