TITLE:   GCN CIRCULAR
NUMBER:  25833
SUBJECT: IceCube-190922B: Upper limits from a search for additional neutrino events in IceCube
DATE:    19/09/24 03:46:20 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-190922B (https://gcn.gsfc.nasa.gov/gcn3/25802.gcn3) in a time
range of 2 days centered on the alert event time (2019-09-21 23:03:55.56 UTC to 2019-09-23 23:03:55.56 UTC) during which IceCube was collecting good quality data. Excluding the
event that prompted the alert, zero additional track-like events are found in spatial coincidence
with the 90% containment region of IceCube-190922B. We find that these data are well described by atmospheric background expectations, with a p-value of 1.0. Accordingly, these data would represent a time-integrated muon-neutrino flux upper limit at the alert position assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 3.3 x 10^-5 TeV cm^-2 for this observation period. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are approximately between 1 TeV and 10 PeV.

A subsequent search was performed to include the previous month of data (2019-08-22 23:03:55.56 UTC to 2019-09-23 23:03:55.56 UTC). In this case, we report a p-value of 0.062,
consistent with no significant excess of track-like events, and a corresponding time-integrated
muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) of
 6.4 x 10^-5 TeV cm^-2 at the 90% CL.

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>.