[vsnet-grb-info 27585] IceCube Astrotrack Bronze 135113_19489408.amon is likely background

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29688
SUBJECT: IceCube Astrotrack Bronze 135113_19489408.amon is likely background
DATE:    21/03/22 03:42:56 GMT
FROM:    Marcos Santander at U. Alabama/IceCube  <jmsantander at ua.edu>

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

On 2021-03-22 at 02:34:09.177018 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 (https://gcn.gsfc.nasa.gov/notices_amon_g_b/135113_19489408.amon <https://gcn.gsfc.nasa.gov/notices_amon_g_b/135113_19489408.amon>). The threshold astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 1.382 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.

Upon further examination of the light deposition pattern of this event in the detector, and in particular due to the presence of light deposition in its veto region, it is likely that it was caused by a down-going muon (background) rather than by a high-energy neutrino. Studies of this event will continue over the coming days and, if the background hypothesis is rejected, we will issue further updates. 

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 at icecube.wisc.edu <mailto:roc at icecube.wisc.edu>