Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 31085

IceCube-211116A : IceCube observation of a high-energy neutrino candidate track-like event
2021-11-16T11:53:55Z (3 years ago)
Cristina Lagunas Gualda at DESY <>
The IceCube Collaboration ( reports:

On 2021/11/16 at 10:33:16.05 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 1.941 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.

Due to a technical problem, the initial automated alert was not issued. Nonetheless, sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2021/11/16
Time: 10:33:16.05 UT
RA: 42.45 (+1.39 -1.50 deg  90% PSF containment) J2000
Dec: +0.15 (+0.98 -0.94 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 sources inside of the 90% error contour. The closest source is 4FGL J0253.2-0124, located at RA 43.32 deg and dec -1.4 deg (J2000), 1.78 deg away from the best-fit 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
Looking for U.S. government information and services? Visit