TITLE:   GCN CIRCULAR
NUMBER:  31249
SUBJECT: IceCube-211216B - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    21/12/17 00:38:31 GMT
FROM:    Erik Blaufuss at U. Maryland/IceCube  <blaufuss@umd.edu>

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

On 2021-12-16 at 23:41:13.93 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 2.39 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/136057_6147475.amon), more  
sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2021-12-16
Time: 23:41:13.93

RA: 199.34 (+1.66/-1.78 deg 90% PSF containment) J2000
Dec: 17.04 (+1.39/-1.36 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.

No gamma-ray sources listed in the 4FGL-DR2 Fermi-LAT catalog are located in the 90% containment region. The closest source is 4FGL J1319.5+1404 at RA: 199.90, Dec: 14.07 (3.02 deg from the best-fit event location).

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