//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28709 SUBJECT: Alert from the HAWC Burst Monitor HAWC-201019A DATE: 20/10/21 00:08:10 GMT FROM: Hugo Ayala at Pennsylvania State University The HAWC Collaboration (http://www.hawc-observatory.org/collaboration/) reports: On 2020-10-19, at 21:43:42 UT, HAWC detected a burst signal from its Burst Monitoring named HAWC-201019A. 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 100-second time window starting at the reported trigger time. The position of the alert is RA (J200): 203.148 deg Dec (J2000): 29.717 deg Location uncertainty (68% containment): 0.6 deg (statistical only). The monitor system found that this alert has a false alarm rate of 2.37 alert(s) per year. We encourage follow-up observations of the HAWC alert region. We however note that it is consistent with background expectation based on the observation time. The initial automated alert is recorded here: https://gcn.gsfc.nasa.gov/gcn/notices_amon_hawc/1009678_72.amon We note that a quick search on the FAVA monitoring (https://fermi.gsfc.nasa.gov/ssc/data/access/lat/FAVA/), an old alert, FAVA_223_2, is 0.29 deg away from HAWC-201019A, which occurred on 2012-11-05 15:43:35. See: https://fermi.gsfc.nasa.gov/ssc/data/access/lat/FAVA/LightCurve.php?ra=203.148&dec=29.717 The source 4FGL J1330.7+2933 is located 0.43 deg away from HAWC-201019A and is also positionally consistent with the FAVA event. 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28729 SUBJECT: HAWC-201019A: No Neutrino Counterpart detected with ANTARES DATE: 20/10/21 20:25:59 GMT FROM: Antoine Kouchner at ANTARES Collaboration Alexis Coleiro (APC/Univ de Paris) and Damien Dornic (CPPM/CNRS) on behalf of the ANTARES Collaboration. Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported HAWC-201019A alert (GCN 28709 ). No up-going muon neutrino candidate events were detected within the error box of the HAWC event during a +/- 1h time-window centered on the HAWC event time (T0), and over which the potential source remained visible all time in the up-going field of view of ANTARES. At T0, the elevation of the alert is -15 degrees below the horizon for ANTARES. This leads to a preliminary 90% confidence level upper limit on the muon-neutrino radiant fluence from a point source of about 17 GeV.cm^-2 over the energy range 7 TeV – 6 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and about 37 GeV.cm^-2 (1 - 630 TeV) for an E^-2.5 spectrum. A search over an extended time window of +/-1 day has also yielded no detection (32% visibility). ANTARES is the largest undersea neutrino detector (Mediterranean Sea) and it is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is about 0.5 degrees. In the range 1-100 TeV ANTARES has a competitive sensitivity to this position in the sky. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28734 SUBJECT: HAWC-201019A: not observable by Fermi-GBM DATE: 20/10/21 22:01:02 GMT FROM: Cori Fletcher at USRA C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team: The HAWC Burst Monitor detected the burst signal HAWC-201019A (GCN 28709) with the reported position: RA: 203.148 deg (J2000) Dec: 29.717 (J2000) which was occulted by the Earth for Fermi-GBM from approximately 14.5 minutes prior until 14.8 minutes after event time. Therefore, the GBM observations are not constraining for prompt gamma-ray emission.