GCN Circular 26709

Hugo Ayala (PSU) reports on behalf of the HAWC
collaboration (http://www.hawc-observatory.org/collaboration):On
2020/01/09 23:41:39 UTC, the IceCube collaboration reported a
track-like very-high-energy event  that has a high probability of
being an astrophysical neutrino, IceCube-200109A. Location is at
RA: 164.49 (+4.94/-41.9  90% PSF containment) J2000
Dec: 11.87 (+1.16/-1.36 deg 90% PSF containment) J2000
https://gcn.gsfc.nasa.gov/gcn3/26696.gcn3
Not found
 
 

(GCN circular 26696
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).


We performed two types of analyses for the follow-up. The first is for
a steady source in archival data and the second is a search for a
transient source. We assume a power-law spectrum with an index of -2.3
for both analyses.


Search for a steady source in archival data:
The archival data spans from November 2014 to November 2019.
We searched inside the IceCube error region from the circular.
The highest significance, 2.77 sigma (0.89 post-trials),
is at RA 167.39 deg, Dec 11.03 deg (+-1.78 deg 68% containment) J2000.
We set a time-integrated 95% CL  upper limit on gamma rays at the
maximum position of:
E^2 dN/dE = 3.02e-13 (E/TeV)^-0.3 TeV cm^-2 s^-1


Search for a transient source.
Since the IceCube event fall inside the HAWC field of view,
we report on the result for the current transit of the IceCube
position.Data acquisition started on Data Start: 2020/01/08 13:01:36
UTC and ended
2020/01/10 13:29:43 UTC.
The most significant location, with 2.40 sigma (-1.76 post-trials),
is at RA 164.0 deg, Dec 11.15 deg (+-1.8 deg 68% containment) J2000.
We set a time-integrated 95% CL upper limit at the position of
maximum significance of:
E^2 dN/dE = 1.12e-11 (E/1TeV)^-0.3 TeV cm^-2 s^-1

HAWC is a very-high-energy gamma-ray observatory operating in Central
Mexico at latitude 19 deg. north. Operating day and night with over
95% duty cycle, HAWC has an instantaneous field of view of 2 sr and
surveys 2/3 of the sky every day. It is sensitive to gamma rays from
300 GeV to 100 TeV.