TITLE:   GCN CIRCULAR
NUMBER:  25806
SUBJECT: IceCube-190922B - IceCube observation of a high-energy neutrino candidate event
DATE:    19/09/23 01:58:33 GMT
FROM:    Erik Blaufuss at U. Maryland/IceCube  <blaufuss@umd.edu>

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

On 19/09/22 at 23:03:55.56 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 1.33 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/133092_52499868.amon), more  
sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 19/09/22
Time:  23:03:55.56 UT
RA: 5.76 (+ 1.19 - 1.37 deg  90% PSF containment) J2000
Dec: -1.57(+ 0.93 - 0.82 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 
J0022.0+0006 at RA: 5.52 deg, Dec: 0.11 deg (1.70 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