GCN Circular 28575

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

On 20/10/07 at 22:01:49.28 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 0.262 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/134577_31638233.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 20/10/07
Time:  22:01:49.28 UT
RA: 265.17 (+/- 0.52 deg  90% PSF containment) J2000
Dec: 5.34 ((+0.32, -0.23) 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 J1736.6+0628 at RA: 264.17 deg, Dec: 6.47 deg J2000 (1.51 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