GCN Circular 27235

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

On 20/02/27 at 05:36:31.50 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 2.34 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/133781_21701751.amon <https://gcn.gsfc.nasa.gov/notices_amon_g_b/133781_21701751.amon>), the detailed angular uncertainty is still being evaluated. At this time we propose to use the preliminary values reported in the GCN Notice:

Date: 20/02/27 
Time: 05:36:31.50 UT
RA:  348.26 deg J2000
Dec: +21.32 deg J2000
Error Radius: 30.80 arcmin (90% containment - statistical)

We stress that the reported error estimate only accounts for statistical errors, and that additional systematic uncertainties mean this containment radius is a lower limit.

We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

The nearest 4FGL sources is 4FGL J2318.2+1915, located at RA 349.56 deg and Dec 19.26 deg a distance of  2.40 deg from the best-fit position. A second source, 4FGL J2323.1+2040, is located at RA 350.79 deg and Dec 20.68 deg, a distance of 2.45 deg from the best-fit 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