//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31249 SUBJECT: IceCube-211216B - IceCube observation of a high-energy neutrino candidate track-like event DATE: 21/12/17 00:38:31 GMT FROM: Erik Blaufuss at U. Maryland/IceCube The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2021-12-16 at 23:41:13.93 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 2.39 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/136057_6147475.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2021-12-16 Time: 23:41:13.93 RA: 199.34 (+1.66/-1.78 deg 90% PSF containment) J2000 Dec: 17.04 (+1.39/-1.36 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. No gamma-ray sources listed in the 4FGL-DR2 Fermi-LAT catalog are located in the 90% containment region. The closest source is 4FGL J1319.5+1404 at RA: 199.90, Dec: 14.07 (3.02 deg from the best-fit event location). 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: 31256 SUBJECT: IceCube-211216B: Upper limits from Fermi-GBM Observations DATE: 21/12/18 00:23:20 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi-GBM team: For the IceCube high-energy neutrino candidate event IceCube-211216B (GCN 31249), at the event time Fermi-GBM was observing the reported neutrino location at: RA: 199.34 (+1.66/-1.78 deg 90% PSF containment) J2000 Dec: 17.04 (+1.39/-1.36 deg 90% PSF containment) J2000 There was no Fermi-GBM onboard trigger around the event time of the neutrino candidate. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around the neutrino candidate time. From this search, no significant signal was found related to IceCube-211216B. We set upper limits on impulsive gamma-ray emission. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------------- 0.128 s: 5.2 8.2 16. 1.024 s: 1.4 2.3 4.7 8.192 s: 0.4 0.7 2.1 These results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31258 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-211216B DATE: 21/12/18 01:10:00 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 high-energy IC211216B neutrino event (GCN 31249) 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 2021-12-16 23:41:13.93 UTC (T0) with J2000 position RA = 199.34 (+1.66, -1.78) deg, Decl. = 17.04 (+1.39, -1.36) deg 90% PSF containment. Two cataloged >100 MeV gamma-ray sources are located within the 90% IC211216B localization error. No cataloged gamma-ray sources are found within the 90% IC211216B localization error (The Fourth Fermi-LAT catalog DR2; The Fermi-LAT collaboration 2020, ApJS, 247, 33). We searched for the existence of intermediate (months to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (>5sigma) new excess emission (0.1 - 300 GeV) within the IC211216B 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IceCube best-fit position, the >100 MeV flux upper limit (95% confidence) is < 3.6-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 / 2021-12-16 UTC), < 1.8e-8 (< 1.2e-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 source 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31262 SUBJECT: IceCube-211216B: No neutrino counterpart candidates in ANTARES search DATE: 21/12/18 09:07:59 GMT FROM: Antoine Kouchner at ANTARES Collaboration Alexis Coleiro (APC/Universite 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 event IceCube-211216B (GCN#31249 ). At the time of the alert, the reconstructed origin was -3.7 degrees below the horizon for ANTARES. No up-going muon neutrino candidate events were recorded within the 90% error box of the IceCube event during a +/- 1h time-window centered on the IceCube event time, and over which the potential source remained visible from [T-60min, T+22min] (68%). This leads to a preliminary 90% confidence level upper limit on the muon-neutrino fluence from a point source of 17 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 40 GeV.cm^-2 (1 TeV - 450 TeV) for an E^-2.5 spectrum. A search over an extended time window of +/- 1 day has also yielded no detection (40% 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: 31272 SUBJECT: IceCube-211216B: No significant detection in HAWC DATE: 21/12/21 20:55:57 GMT FROM: Hugo Ayala at Pennsylvania State University Hugo Ayala (Penn State) reports on behalf of the HAWC collaboration (http://www.hawc-observatory.org/collaboration): On 2021/12/16 23:41:13.93 UTC, the IceCube collaboration reported a track-like very-high-energy event that has a high probability of being an astrophysical neutrino, IceCube-211216B. Location is at RA: 199.34 (+1.66/-1.78 deg 90% PSF containment) J2000 Dec: 17.04 (+1.39/-1.36 deg 90% PSF containment) J2000 (GCN circular 31249). We performed two types of analyses for the follow-up. The first is for a steady source in archival data and the second is a search for a transient source. We assume a power-law spectrum with an index of -2.3 for both analyses. Search for a steady source in archival data: The archival data spans from November 2014 to June 2019. We searched inside the reported IceCube error region. The most significant location, with p-value 1.4e-3 (6.3e-2 post-trials), is at RA 198.19 deg, Dec +116.53 deg (±0.6 deg 68% containment) J2000. We set a time-integrated 95% CL upper limit on gamma rays at the maximum position of: E^2 dN/dE = 2.13e-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, we report the combined result for the transits before and after the IceCube event. Data acquisition started on 2021/12/15 18:23:07 UTC and ended 2021/12/17 17:15:21 UTC. The most significant location, with p-value 5.1e-3 (2.2e-1 post-trials), is at RA 198.28 deg, Dec +17.47 deg (±0.20 deg 68% containment) J2000. We set a time-integrated 95% CL upper limit at the position of maximum significance of: E^2 dN/dE = 9.68e-12 (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.