[vsnet-grb-info 23837] IceCube-191001A: HAWC follow-up

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25936
SUBJECT: IceCube-191001A: HAWC follow-up
DATE:    19/10/03 13:58:22 GMT
FROM:    Hugo Ayala at Pennsylvania State University  <hgayala at psu.edu>

Hugo Ayala reports on behalf of the HAWC collaboration (
http://www.hawc-observatory.org/collaboration/):

On 2019/10/01 at 20:09:18.17 UTC, the IceCube collaboration detected a
track-like
event with a high probability of being of astrophysical origin named
IceCube-1901001A.
The revised position is  RA= 314.08 deg and Dec= 12.94 deg, J2000 (GCN
circular 25913).
We have performed a search in our archival data for a steady source as
well as a transient source. We assume a power-law spectrum with a spectral
index of -2.3.
We use this spectrum for both analyses.

* Search for a steady source: Archival data from November 2014 to May
2018 is used.
We searched inside the uncertainty region reported by IceCube in the
circular (8.82 deg x 2.97 deg).
The highest significance found is 4.03 sigmas, at RA= 313.46 deg, Dec=
14.48 deg (J2000).
Note that there are at least 133 trials in this search, so the post-trials
significance is consistent with a non-detection.
We set a 95% CL time-integrated upper limit on the gamma-ray flux of E^2
dN/dE = 2.3e-13 (E/TeV)^-0.3 TeV cm^-2 s^-1.

*Search for a transient source: Since the event was not in our field of
view at the time reported on the GCN we report the combined result for the
transit before and
after the time of the IceCube event. We obtain the following results:
Data acquisition started on 2019/09/30 05:46:52 UTC and ended 2019/10/02
06:03:29 UTC.
The most significant location, with a pre-trials value of 2.55 sigma,  is
at RA= 313.84 deg, Dec= 12.71 deg (J2000).
We set a time-integrated 95% CL upper limit on the gamma-ray flux at the
position
of maximum signficance of: E^2 dN/dE = 3.51e-13 (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.