//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32599 SUBJECT: IceCube-220928A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 22/09/28 13:32:31 GMT FROM: Dr. Massimiliano Lincetto at Ruhr-Universitaet Bochum The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 22-09-28 at 12:32:38.30 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin.  The event was selected by the ICECUBE_Astrotrack_Bronze alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 1.99 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/137096_70551815.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 22-09-28 Time: 12:32:38.30 RA: 207.42 (+1.41 / -2.52 deg  90% PSF containment) J2000 Dec: +10.43 (+0.98 / -0.98 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. Two gamma-ray sources listed in the 4FGL-DR2 Fermi-LAT catalog are located within the 90% containment of the best-fit candidate neutrino position. The sources are 4FGL J1351.3+1115 and 4FGL J1342.6+0944, located 0.92 and 1.86 deg away from the best-fit position, respectively. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32601 SUBJECT: IceCube-220928A: Upper limits from a search for additional neutrino events in IceCube DATE: 22/09/29 21:06:32 GMT FROM: Jessie Thwaites at IceCube/U Wisc-Madison The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-220928A (https://gcn.gsfc.nasa.gov/gcn3/32599.gcn3) in a time range of 1000 seconds centered on the alert event time (2022-09-28 12:24:18.300 UTC to 2022-09-28 12:40:58.300 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-220928A. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-220928A is 1.3e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 1e+05 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2022-09-27 12:32:38.300 UTC to 2022-09-29 12:32:38.300 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-220928A is 1.5e-01 GeV cm^-2 in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32602 SUBJECT: Fermi-LAT gamma-ray observations of IceCube-220928A DATE: 22/09/29 21:21:24 GMT FROM: Simone Garrappa at DESY S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and J. Sinapius (DESY-Zeuthen) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the IC220928A high-energy neutrino event (GCN 32599) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2022-09-28 at 12:32:38.30  UT (T0) with J2000 position RA = 207.42 (+1.41 , -2.52) deg, Decl. = 10.43 (+0.98 , -0.98) deg (90% PSF containment). Three cataloged gamma-ray (>100 MeV) sources are located within the 90% IC220928A localization region (4FGL-DR3; The Fermi-LAT collaboration 2022, ApJS, 260, 53). Based on a preliminary analysis of the LAT data over the timescales of 1-day and 1-month prior to T0, these objects are not significantly detected (> 5 sigma). We searched for intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (> 5 sigma) new excess emission (> 100 MeV) at the IC220928A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC220928A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 6.5e-10 ph cm^-2 s^-1 for ~14-years (2008-08-04 to 2022-09-28 UTC), and < 9e-9 (<1.1e-7) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0. Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this region will continue. For these observations the Fermi-LAT contact persons are S. Garrappa (simone.garrappa at desy.de) and S. Buson (sara.buson at uni-wuerzburg.de). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.