[vsnet-grb-info 27848] IceCube-210503A: IceCube observation of a high-energy neutrino candidate event

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29951
SUBJECT: IceCube-210503A: IceCube observation of a high-energy neutrino candidate event
DATE:    21/05/06 16:40:37 GMT
FROM:    Marcos Santander at U. Alabama/IceCube  <jmsantander at ua.edu>

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

On 21/05/03 at 22:19:32.96 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 0.658 events per year due to atmospheric backgrounds. At the time of the event detection, IceCube was in a test run configuration and therefore no automated alert was circulated via GCN Notices. 

Once the data quality was verified, more sophisticated reconstruction algorithms were applied offline, with the direction refined to:

Date: 21/05/03
Time: 22:19:32.96 UT
RA: 143.53 (+7.71, -5.16 deg 90% PSF containment) J2000
Dec: 41.81 (+5.02, -5.68 deg 90% PSF containment) J2000

The directional uncertainty is larger than usual for this type of alert, as the event was produced by a short muon track clipping a corner of the IceCube detector volume. We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

Given the large directional uncertainty, there are 14 Fermi-LAT 4FGL sources within the 90% localization region, one of them is also listed in the 3FHL catalog. The nearest source in either catalog is 4FGL J0928.5+4048 (RA: 142.15 deg, Dec: 40.81 deg J2000, 1.44 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 roc at icecube.wisc.edu