TITLE:   GCN CIRCULAR
NUMBER:  23926
SUBJECT: Search for additional neutrino events from the direction of IceCube-190221A with IceCube
DATE:    19/02/22 20:57:41 GMT
FROM:    Alex Pizzuto at ICECUBE/U of Wisconsin  <pizzuto@wisc.edu>

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

IceCube has performed a search for additional track-like muon neutrino events arriving
from the direction of IceCube-190221A (https://gcn.gsfc.nasa.gov/gcn3/23918.gcn3) in a time
range of 2 days centered on the alert event time (2019-02-20 08:25:40.00 UTC to 2019-02-22
08:25:40.00 UTC) during which IceCube was collecting good quality data. Excluding
the event that prompted the alert, 2 additional track-like events are found in spatial coincidence
with the 90% PSF containment of IceCube-190221A. We find that these 2 additional events are
well described by atmospheric background expectations, with a p-value of 0.08. Accordingly,
these data would represent a time-integrated muon-neutrino flux upper limit assuming an E^-2
spectrum (E^2 dN/dE) at the 90% CL of 2.71 x 10^-4 TeV cm^-2 for this observation period.

A subsequent search was performed to include the previous month of data (2019-01-21
08:25:40.00 UTC to 2019-02-22 08:25:40.00 UTC). In this case, we report a p-value of 1.0,
consistent with no significant excess of track events, and a corresponding
time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 3.5 x 10^-4 TeV cm^-2.

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<mailto:roc@icecube.wisc.edu>