[vsnet-grb-info 18800] HAWC follow-up on IceCube-161210

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20250
SUBJECT: HAWC follow-up on IceCube-161210
DATE:    16/12/13 18:15:22 GMT
FROM:    Israel Martinez at HAWC  <imc at umd.edu>

Israel Martinez (University of Maryland) reports on behalf of the HAWC
collaboration (http://www.hawc-observatory.org/collaboration/):

On 2016/12/10 20:07:16 UT IceCube detected a track-like,
very-high-energy event with a high probability of being of
astrophysical origin, at RA=46.58d and Dec=14.98d J2000.
It was reported in GCN circular 20247.

Two analyses were performed:

* Search for a steady source.
This analysis was performed on archival data from November 2014 to
June 2016. Assuming a spectral index of -2.3 we searched in a
rectangular window corresponding to IceCube's 90% PSF containment for
the event (1.72deg^2). The maximum significance is 2.83 sigma at
RA=47.46d and Dec=14.59d. We estimate the number of trials to be ~70.
We set an upper limit 95% CL on gamma rays for this period of:
E^2 dN/dE = 3.23e-13 (E/TeV)^-0.3 TeV cm^-2 s^-1.

* Search for a transient source.
The event location was not in HAWC's FOV at the time of detection, so
this analysis was performed using data corresponding to the two nearest
6hrs transits (MJD 57732.05-57732.30 and 57733.05-57733.30). Using the
same spectral index and search window, the maximum significance is
1.71 sigma at RA=46.57d and Dec=15.18d. We set an upper limit 95% CL
on gamma rays for this period of:
E^2 dN/dE = 1.54e-11 (E/TeV)^-0.3 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 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.