TITLE: GCN CIRCULAR NUMBER: 19361 SUBJECT: Archival observations by HAWC of IceCube HESE event of April 27, 2016 DATE: 16/04/29 12:24:04 GMT FROM: Ignacio Taboada at Georgia Inst of Tech 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/