TITLE:   GCN CIRCULAR
NUMBER:  40153
SUBJECT: IceCube-250416A - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    25/04/16 20:17:54 GMT
FROM:    A. Zegarelli at Ruhr University Bochum <azegarelli@icecube.wisc.edu>

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

On 25-04-16 at 18:32:14.97 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 2.3036 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/140799_37236133.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 25-04-16
Time: 18:32:14.97 UT
RA: 83.1 (+0.57/-0.58 deg 90% PSF containment) J2000
Dec: 15.64 (+0.49/-0.5 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.

No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region 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