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GCN Circular 28468

IceCube-200921A: IceCube observation of a high-energy neutrino candidate event
2020-09-21T20:36:22Z (4 years ago)
Cristina Lagunas Gualda at DESY <>
The IceCube Collaboration ( reports:

On 20/09/21 at 19:07:12.89 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 1.586 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: 20/09/21
Time: 19:07:12.89  UT
RA: 195.29 (+ 2.35 - 1.73  deg 90% PSF containment) J2000
Dec:  26.24 (+ 1.51  - 1.77  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  Fermi 4FGL/3FHL source located within the 90% localization region, 4FGL J1303.0+2434, located at RA: 195.76 deg, Dec: 24.58 deg (J2000), at a distance of 1.71 deg 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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