GCN Circular 28592

Alberto Carrami��ana (INAOE) reports on behalf of the HAWC
collaboration (http://www.hawc-observatory.org/collaboration):

On 2020/10/07 22:01:49 UTC, the IceCube collaboration reported a 
track-like very-high-energy event  that has a high probability of 
being an astrophysical neutrino, IceCube-201007A. Location is at
RA: 265.17 (+/-0.52 deg  90% PSF containment) J2000
Dec: 5.34 (+0.32/-0.23 deg 90% PSF containment) J2000  
(GCN circular 28575
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 ).

We performed two types of analyses for the follow-up. The first is for
a steady source in archival data and the second is a search for a 
transient source. We assume a power-law spectrum with an index of -2.3
for both analyses. 

- Search for a steady source in archival data:
The archival data spans from November 2014 to June 2019. We searched
inside the reported IceCube error region. 
The most significant location, with p-value 1.29e-02 (3.70e-02 post-trials), 
is at RA 264.86 deg, Dec +5.23 deg (��0.15 deg 68% containment) J2000. 
We set a time-integrated 95% CL  upper limit on gamma rays at the 
maximum position of:

E^2 dN/dE = 2.57e-13 (E/TeV)^-0.3 TeV.cm^-2.s^-1

- Search for a transient source. 
The IceCube event was in our field of view at the time reported.

Data acquisition started on 2020/10/07 20:06:38 UTC and ended
2020/10/08 01:58:29 UTC.
The most significant location, with p-value 3.97e-01 (7.71e-01 post-trials),
is at RA 265.25 deg, Dec +5.34 deg (��0.27 deg 68% containment) J2000.
We set a time-integrated 95% CL upper limit at the position of 
maximum significance of:

E^2 dN/dE = 6.47e-12 (E/TeV)^-0.3 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.