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GCN Circular 24028

IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
2019-03-31T19:12:37Z (5 years ago)
Claudio Kopper at IceCube/U of Alberta <>
The IceCube Collaboration ( reports:

On March 31, 2019, IceCube detected a track-like, very-high-energy event with a high probability of being produced by a muon neutrino of astrophysical origin. The event was identified by the High Energy Starting Event (HESE) track selection. The IceCube detector was in a normal operating state. HESE tracks have a neutrino interaction vertex inside the detector and produce a muon that only partially traverses the detector volume, and have a high light level (a proxy for energy).

After the initial automated alert was issued, visual inspection of the event revealed that the online directional reconstruction reported in the original GCN ( was very incorrect, biased by the topology of the event. More sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2019/03/31 
Time: 06:55:43.44 UT 
RA: 337.68deg (+0.23deg -0.34deg 90% PSF containment) J2000
Dec:  -20.70deg (+0.30deg -0.48deg 90% PSF containment) J2000

Additionally, given the large deposited energy observed in this event (one of the highest observed so far), it has a very high likelihood of being of astrophysical origin. We strongly 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 catalog sources in the 90% region. The nearest source is 1RXS J223249.5-202232 (4FGL J2232.6-2023) at RA: 338.1725deg, Dec: -20.3909deg.

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 .
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