TITLE:   GCN CIRCULAR
NUMBER:  35192
SUBJECT: IceCube-231125A - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    23/11/26 16:00:03 GMT
FROM:    Giacomo Sommani at Ruhr-Universität Bochum <gsommani@icecube.wisc.edu>

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

On 2023-11-25 at 22:34:56.64 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 average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 0.1472 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/138599_39138591.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2023-11-25
Time:  22:34:56.64 UT
RA: 177.53 (+2.20, -2.27 deg  90% PSF containment) J2000
Dec: +53.62 (+1.57, -1.64 deg 90% PSF containment) J2000

An error in the automatic processing pipeline that performs the offline reconstruction resulted in a delay in the circulation of the updated position. Therefore, an alternative reconstruction algorithm has been applied to this event. 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 J1202.9+5141 at RA: 180.74 deg, Dec: +51.69 deg (2.74 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