[vsnet-grb-info 22765] IceCube-190619A - HAWC follow-up

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24864
SUBJECT: IceCube-190619A - HAWC follow-up
DATE:    19/06/20 14:21:26 GMT
FROM:    Israel Martinez-Castellanos at UMD/HAWC  <imc at umd.edu>

Antonio Galván (IA-UNAM), Israel Martinez-Castellanos (UMD) and Ignacio
Taboada (GaTech) report on behalf of the HAWC
collaboration (http://www.hawc-observatory.org/collaboration/):

On June 19, 2019, 13:14:18.04 UT, the IceCube collaboration reported a
track-like very-high-energy event that has a high probability of being
an astrophysical neutrino, IceCube-190619A, at RA 343.26 deg and Dec
10.73 deg, J2000 (GCN circular 24854). In HAWC's sky, the neutrino
was at zenith of 26.44 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
May 2018. Assuming a spectral index of -2.3 we searched in a 4.08
degree circle around IceCube's reported location. The highest
significance, 3.02 sigma, was at RA= 344.88 deg, Dec= 13.28 deg
(J2000). Note that there are at least 200 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 = 2.59e-13 (E/TeV)^-0.3 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 2019/06/19 08:30:06 UTC / stop
2019/06/19 14:37:06 UTC). The most significant location, within 4.08
deg, is 3.44 sigma (RA = 338.93 deg, Dec = 9.99 deg, J2000).
We set a time-integrated upper limit 95% CL on gamma rays of:
E^2 dN/dE = 1.56e-11 (E/TeV)^-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.