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

GCN Circular 34528

IceCube-230823A: Event likely due to background
2023-08-23T15:37:33Z (8 months ago)
Marcos Santander at U of Alabama <>
legacy email
The IceCube Collaboration ( reports:

On 23/08/23 IceCube reported a track-like event with a high probability of being of astrophysical origin ( After further study, we now believe this event to likely be due to a highly inclined muon bundle. Muon bundles are a background arising from down-going cosmic-ray air showers and are not from a neutrino of astrophysical origin.

This conclusion is driven by observations with the IceTop surface array portion of IceCube at the time of the alert. The IceTop surface array detects charged particles from cosmic ray induced extensive air showers that occur in the atmosphere above the IceCube detector. A preliminary offline cross check of IceTop data indicates a background origin for this alert.

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