//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28074 SUBJECT: HAWC-200907A: No Neutrino Counterpart detected with ANTARES DATE: 20/07/10 12:22:03 GMT FROM: Damien Dornic at CPPM,France 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-200709A alert (Notice https://gcn.gsfc.nasa.gov/notices_amon_hawc/1009500_793.amon ).

No up-going muon neutrino candidate events were detected within 3 degrees from the event coordinates over a time window of [T0-0.3h, T0+9.7h] where T0 is the time of the HAWC alert, and during which the potential source remained visible in the up-going field of view of ANTARES. At T0, the elevation of the alert is -3.8 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 40 GeV.cm^-2 over the energy range 5 TeV – 5 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and about 240 GeV.cm^-2 (860 GeV - 430 TeV) for an E^-2.5 spectrum, computed for the time of the Swift Busrt Alert.

A search over an extended time window of +/-1 day has also yielded no detection (42% 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: 28075 SUBJECT: GRB 200709B/HAWC-200907A: Swift-XRT further observations DATE: 20/07/10 18:04:03 GMT FROM: Antonino D'Ai at IASF-PA A. DAi (INAF/IASFPA), E. Ambrosi (INAF/IASFPA), V. D'Elia (ASDC) report on behalf of the Swift XRT team. Swift performed a second observation for the candidate Source 1 present in the field of GRB 200709B/HAWC-200907A (Osborne et al., GCN 28072), with a 3.0 ks exposure between T0+52.6 ks and T0+40.0 ks. Source 1 is still detected at the same flux level and it is therefore unlikely to be the afterglow. This circular is an official product of the Swift XRT team.