GCN Circular 19361

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

On April 27, 2016, the IceCube collaboration reported a track-like very 
high energy event that has a high probability of being an astrophysical 
neutrino (HESE Alert 
127853_67093193http://gcn.gsfc.nasa.gov/notices_amon/67093193_127853.amon). 
With a declination of 9.34 deg (J2000), this event is in the field of 
view of HAWC.

The HAWC gamma-ray observatory is currently not operating due to a power 
failure. However, we have searched for time integrated TeV scale 
emission using 341 days of data collected between November 2014 and 
December 2015.

Within the 0.6 degree 50% PSF containment region reported by IceCube, 
the most significant point in the sky is RA = 240.38 and Dec = 9.86 
(J2000), with a pre-trial significance of 1.2 standard deviations. There 
are approximately 20 trials in this search region.So, there is no 
evidence for a steady TeV source at this location.

We have calculated the necessary flux to perform a 5 sigma pre-trials 
observation with 50% probability at the location reported by IceCube. 
Assuming a power law spectrum with index -2.3, this flux is:

dN/dE = A (E/E_0)^-2.3 with A= 6.5x10^-13 /(TeV.cm^2.s) and  E_0 = 1 TeV.

HAWC is a very-high-energy gamma-ray observatory operating in Central 
Mexico at a latitude of 19 deg north. 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.


-- 
Ignacio Taboada - Associate Professor
Center for Relativistic Astrophysics
School of Physics - Georgia Institute of Technology
837 State St. NW, Atlanta GA 30332-0430
Office +1(404)385-7679 | Fax +1(404)385-0830
http://taboada.gatech.edu/