GCN Circular 35984

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

On 2024-03-27, at 16:12:30.47 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 Gold alerts is 30%. This alert has an estimated false alarm rate of 2.420 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/139205_9784024.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2024-03-27
Time:  16:12:30.47 UT
RA: 89.21 (+1.36, -1.55 deg  90% PSF containment) J2000
Dec: 0.93 (+1.23, -1.47 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.

Five known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of the event. The nearest one to the neutrino alert position is 4FGL J0555.9+0030, located at RA = 89.00 deg, Dec = 0.51 deg J2000, 0.47 deg away from the best-fit alert 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