TITLE:   GCN CIRCULAR
NUMBER:  34265
SUBJECT: IceCube-230724A - IceCube observation of a high-energy neutrino candidate track-like event
DATE:    23/07/26 01:43:56 GMT
FROM:    Marcos Santander at U of Alabama <jmsantander@ua.edu>

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

On 2023-07-24 at 01:49:13.38 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 average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 1.174 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/138181_66037171.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2023-07-24
Time:  01:49:13.38 UT
RA: 32.52 (+0.58, -0.40 deg  90% PSF containment) J2000
Dec: -1.87 (+0.23, -0.33 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-DR3 or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J0212.2-0219 at RA: 33.07 deg, Dec: -2.32 deg (0.71 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