Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 30559

IceCube-210730A - IceCube observation of a high-energy neutrino candidate track-like event
2021-07-31T00:19:51Z (3 years ago)
Marcos Santander at U. Alabama/IceCube <>
The IceCube Collaboration ( reports:

On 2021-07-30 at 22:12:40.629 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 2.542 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: 2021-07-30
Time:  22:12:40.629 UT
RA: 105.73 (+2.00, -1.85 deg  90% PSF containment) J2000
Dec: 14.79 (+0.91, -0.86 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 listed in the 4FGL Fermi-LAT catalog is located within the 90% uncertainty region of the best-fit candidate neutrino position. The source is 4FGL J0659.7+1416, 0.92 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