GCN Circular 26258

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

On Nov 19, 2019 at 01:01:29.38 UT IceCube detected a track-like event with a high probability of being of astrophysical origin.  The event was selected by the ICECUBE_Astrotrack_GOLD alert stream.  The threshold astrophysical neutrino purity  for Gold alerts is 50%. This alert has an estimated false alarm rate of 1.54 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/133331_47828126.amon), more  sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 19/11/19 (yy/mm/dd)
Time:  01:01:29.38 UT
RA: 230.10 (+4.76/-6.48 deg  90% PSF containment) J2000
Dec: 3.17 (+3.36/-2.09 deg 90% PSF containment) J2000

The geometry of this event was near the edge of the instrumented volume of IceCube and yielded a somewhat larger 90% uncertainty region when compared to typical realtime alert events. We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

Several gamma-ray sources listed in the 4FGL Fermi-LAT catalog are located within 90% containment region about the best-fit candidate neutrino position. The closest source is
4FGL J1518.8+0203, located 1.2 deg away from the best-fit position. A total of 11 sources listed in the 4FGL catalog are contained in a 5 deg radius from the best-fit position, which approximately corresponds to the 90% containment radius of the event.

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