[vsnet-grb-info 18672] HAWC follow up of IceCube-161103

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20120
SUBJECT: HAWC follow up of IceCube-161103
DATE:    16/11/03 15:48:45 GMT
FROM:    Ignacio Taboada at Georgia Inst of Tech  <itaboada at gatech.edu>

Ignacio Taboada (Georgia Tech) reports on behalf of the HAWC collaboration (http://www.hawc-observatory.org/collaboration/):

On Nov 3, 2016, 09:07:31 UT, the IceCube collaboration reported a track-like very-high-energy event that has a high probability of being an astrophysical neutrino, IceCube-161103, at RA 40.83 deg and Dec 12.56 deg, J2000 (GCN circular 20119). In HAWC’s sky, the neutrino was at zenith of 40.41 deg and setting. We have searched for a steady source as well as a transient source.

* Search for a steady source in archival data from November 2014 to June 2016. Assuming a spectral index of -2.7 we searched in a 1.1 degree circle around IceCube’s reported location. The highest significance, 2.39 sigma, was at RA= 40.12 deg, Dec= 13.09 deg (J2000). Note that there are at least 50 trials in this search, so post-trials significance is lower. We set a time-integrated upper limit 95% CL on gamma rays of:

E^2 dN/dE = 1.27e-12 (E/TeV)^-0.7 TeV.cm^-2.s^-1

* Search for a transient source. We have studied the transit of the event in HAWC’s field of view (start 2016/11/03 03:16:09 UTC / stop 2016/11/03 09:27:09 UTC). The most significant location, within 1.1 deg, is 1.1 sigma (RA = 41.26 deg, Dec= 12.18 deg, J2000).

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.