[vsnet-grb-info 20026] HAWC follow-up of IceCube-171106A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22114
SUBJECT: HAWC follow-up of IceCube-171106A
DATE:    17/11/09 22:42:33 GMT
FROM:    Simone Dichiara at UNAM  <sdichiara at astro.unam.mx>

Simone Dichiara (UNAM-IA), Israel Martinez (University of Maryland),
J.A. García-González (UNAM-IF), Ignacio Taboada (Georgia Tech)
report on behalf of the HAWC collaboration
(https://www.hawc-observatory.org/collaboration/):

On 2017/11/06 18:39:39.21 UT IceCube detected a track-like,
very-high-energy event with a high probability of being of
astrophysical origin, at RA=340.00d and Dec=+7.40d J2000
as reported in GCN circular 22105.

The event was not in the field of view of HAWC, so we
analyze the data following two different approaches:

*We searched for a steady source in archival data from November
2014 to September 2017.  Assuming a spectral index of -2.5 we
searched in the reported 90% PSF containment circle.The maximum
significance is 1.57 sigma at RA=339.48deg and Dec=7.78deg. We
estimate the number of trials to be ~20. We set an upper limit
95% CL on gamma rays for this period of:

E^2 dN/dE = 4.60e-13 (E/TeV)^-0.5 TeV cm^-2 s^-1.

*We also performed a study using data corresponding to the two
nearest transits of IceCube-171106 in HAWC’s field of view (MJD
58062.96-58063.22 and 58063.95-58064.21). Using the same spectral
index and search window, the maximum significance is 1.2 sigma at
RA=340.35deg and Dec=7.12deg.
We set an upper limit 95% CL on gamma rays for this period of:

E^2 dN/dE = 9.38e-12 (E/TeV)^-0.5 TeV cm^-2 s^-1.

HAWC is a very-high-energy gamma-ray observatory located in
Central Mexico at latitude 19 deg North. It operates 24 hours
per day 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.