{
  "bibcode": "2019GCN.24028....1I",
  "body": "The IceCube Collaboration (http://icecube.wisc.edu/) reports:\n\nOn 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).\n\nAfter the initial automated alert was issued, visual inspection of the event revealed that the online directional reconstruction reported in the original GCN (https://gcn.gsfc.nasa.gov/notices_amon/15947448_132379.amon) was very incorrect, biased by the topology of the event. More sophisticated reconstruction algorithms have been applied offline, with the direction refined to:\n\nDate: 2019/03/31 \nTime: 06:55:43.44 UT \nRA: 337.68deg (+0.23deg -0.34deg 90% PSF containment) J2000\nDec:  -20.70deg (+0.30deg -0.48deg 90% PSF containment) J2000\n\nAdditionally, 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.\n\nThere 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.\n\nThe 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 .",
  "circularId": 24028,
  "createdOn": 1554059557000,
  "email": "ckopper@icecube.wisc.edu",
  "subject": "IceCube-190331A - IceCube observation of a high-energy neutrino candidate event",
  "submitter": "Claudio Kopper at IceCube/U of Alberta  <ckopper@icecube.wisc.edu>",
  "eventId": "IceCube-190331A"
}