TITLE:   GCN CIRCULAR
NUMBER:  29976
SUBJECT: IceCube-210510A - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    21/05/10 07:50:58 GMT
FROM:    Marcos Santander at U. Alabama/IceCube  <jmsantander@ua.edu>

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

On 21/05/10 at 04:50:10.73 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 3.944 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/135270_69188496.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: 

Date: 21/05/10
Time:   04:50:10.73
RA: 268.42 (+1.47, -1.60 deg  90% PSF containment) J2000
Dec: 3.81 (+0.68, -0.64 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.

There are no Fermi 4FGL or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J1756.3+0236 at RA: 269.09 deg, Dec: 2.61 deg J2000 (1.37 deg away from the best-fit event 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@icecube.wisc.edu