[vsnet-grb-info 22897] IceCube-190704A - HAWC follow-up

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24996
SUBJECT: IceCube-190704A - HAWC follow-up
DATE:    19/07/06 20:27:29 GMT
FROM:    Antonio Galvan at Inst.de Astronomia,UNAM  <agalvan at astro.unam.mx>

Antonio Galván (IA-UNAM), José Andrés García-González (IF-UNAM) and Israel
Martinez-Castellanos(UMD) reports on behalf of the HAWC collaboration (
http://www.hawc-observatory.org/collaboration/):


On 2019-07-04 at 18:48:52.25 UTC, the IceCube collaboration reported a
track-like event with a moderate probability of being of astrophysical
origin, IceCube-190704A, at RA 161.85 deg and Dec 27.11 deg, J2000 (GCN
circular 24981). In HAWC's sky, the neutrino was at zenith of 50.62  deg
and outside of our field of view. 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  power law with a spectral index of -2.3 we searched in a
4.08 degree circle around IceCube's reported location.

The highest significance, 2.75 sigma, was at RA= 162.47 deg, Dec= 26.28 deg
(J2000). Note that there are at least 250 trials in this search, so
post-trials significance is lower and equal to 0.65. We set a
time-integrated upper limit 95% CL on gamma rays of E^2 dN/dE = 2.52e-13
(E/TeV)^-2.3 TeV cm^-2 s^-1

* Search for a transient source: Since the events was not in our filed of
view at the time reported on the GCN we did a search for the day before as
well. The results are the following:

1.) 2019-07-03
Transit starts on 2019-07-03 19:17:59 and ends 2019-07-04 01:44:07 (UTC)

The highest significance, 4.06 sigma pre-trials (2.45 post trials), was at
RA= 161.67 deg, Dec= 26.80 deg (J2000). We set a time-integrated upper
limit 95% CL on gamma rays of: E^2 dN/dE = 1.98e-11 (E/TeV)^-2.3 TeV cm^-2
s^-1

2.) 2019-07-04
Transit starts on 2019-07-04 19:14:03 and ends 2019-07-05 01:40:11  (UTC)

The highest significance, 2.56 sigma pre-trials (zero post trials), was at
RA= 160.09 deg, Dec= 27.80 deg (J2000). We set a time-integrated upper
limit 95% CL on gamma rays of: E^2 dN/dE = 1.11e-11 (E/TeV)^-2.3 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.