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GCN Circular 28715

IceCube-201021A: IceCube observation of a high-energy neutrino candidate event
2020-10-21T09:18:00Z (4 years ago)
Cristina Lagunas Gualda at DESY <>
The IceCube Collaboration ( reports:

On 20/10/21 at 06:37:47.48 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 2.987 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: 20/10/21
Time: 06:37:47.48  UT
RA: 260.82 (+ 1.73 - 1.68  deg 90% PSF containment) J2000
Dec: 14.55 (+ 1.35 - 0.74  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-LAT 4FGL or 3FHL sources inside the 90% localization region. The closest source is 4FGL J1728.0+1216 located at RA 262.02 deg and Dec 12.28 deg (J2000), at a distance of 2.56 degrees from the best-fit location.

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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