GCN Circular 25766

The HAWC Collaboration
(http://www.hawc-observatory.org/collaboration/) reports:On September
17, 2019, at 01:14:19 UT, HAWC detected a burst signal from its Burst
Monitoring named HAWC-190917A. This monitor system looks for excesses
above the expected background in time windows of 0.2, 1, 10 and 100
seconds. This event was found in the 1-second time window starting at
the reported trigger time. The position of the alert is RA (J200):
321.84 deg
Dec (J2000): 30.97 deg
Location uncertainty (68% containment): 0.8 deg (statistical only).
The monitor system found that this alert has a false alarm rate of
7.78 alert(s) per year. We strongly encourage follow-up observations
of the HAWC alert region. The initial automated alert is recorded in
here: https://gcn.gsfc.nasa.gov/notices_amon_hawc/18941_372.amon. 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.

[GCN OPS NOTE(22sep19): Per author's request, in the SUBJECT-line
the "190916A" was changed to "190917A"; the date in the first
sentence was changed from "September 16" to September 17", and
the ID name was changed from "HAWC-190916A" to "HAWC-190917A".]