TITLE:   GCN CIRCULAR
NUMBER:  23380
SUBJECT: Search for counterparts to IceCube-181023A with IceCube
DATE:    18/10/24 21:59:48 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-181023A
(https://gcn.gsfc.nasa.gov/gcn3/23375.gcn3) in a time range of
2 days centered on the alert event time (2018-10-22 16:37:32 UTC
to 2018-10-24 16:37:32 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-181023A. 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 assuming an E^-2 spectrum (E^2 dN/dE) at
the 90% CL of 9.71 x 10^-5 TeV cm^-2  for this observation period.

A subsequent search was performed to include the previous month of
data (2018-09-23 16:37:32 UTC to 2018-10-24 16:37:32 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 2.66 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