TITLE:   GCN CIRCULAR
NUMBER:  31679
SUBJECT: IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    22/03/04 18:57:39 GMT
FROM:    Erik Blaufuss at U. Maryland/IceCube  <blaufuss@umd.edu>

The IceCube Collaboration (http://icecube.wisc.edu/) reports:

On 4 March 2022 at 17:44:12.21 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 0.58 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 (https://gcn.gsfc.nasa.gov/notices_amon_g_b/136388_4701751.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2022-03-04
Time:  17:44:12.21 UT
RA: 48.78 (+7.68/-6.24 deg  90% PSF containment) J2000
Dec: 4.48 (+5.91/-4.96 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.

Given the size of the 90% event containment region, many gamma-ray sources listed in the 4FGL-DR2 Fermi-LAT catalog are consistent with the best-fit candidate neutrino position. The 
sources 4FGL J0321.3+0425 is the closest, at 1.54 degrees from the best fit direction.

The large uncertainty region arises from the partially-contained nature of this event, being detected at the edge of the IceCube instrumented volume.  

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 roc@icecube.wisc.edu