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 26696

IceCube-200109A: IceCube observation of a high-energy neutrino candidate event
2020-01-10T01:14:56Z (4 years ago)
Robert Stein at DESY <>
The IceCube Collaboration ( reports:

On 20/01/09 at 23:41:39.94 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_Gold alert stream.  The average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 0.64 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: 20/01/09 
Time: 23:41:39.94 UT
RA: 164.49 (+4.94 -4.19 deg 90% PSF containment) J2000
Dec: 11.87 (+1.16 -1.36 deg 90% PSF containment) J2000

Due to the unique topology of this event, with a partially-contained track in the detector, it was challenging for online algorithms to reconstruct. The initially-reported direction was offset from this updated best-fit position by approximately 3 degrees.

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 source within the 90% localization region, 4FGL J1103.0+1157    at RA: 165.77 deg, Dec: 11.97 deg (1.26 deg away from the best-fit event position). This source, which is associated with the quasar TXS 1100+122 at z=0.91, is also found in the 3FHL catalog.

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