//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31124 SUBJECT: IceCube Alert 211125.27: Global MASTER-Net observations report DATE: 21/11/25 12:39:14 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina, A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the IceCube Alert 211125.27 (trigger No 74588253,02h 54m 39.84s , +21d 32m 31.2s, R=1.08) errorbox 201 sec after notice time and 242 sec after trigger time at 2021-11-25 06:26:23 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 69 deg. The sun altitude is -30.2 deg. The galactic latitude b = -32 deg., longitude l = 158 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1795993 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 277 | 2021-11-25 06:26:23 | MASTER-OAFA | (02h 54m 54.02s , +20d 45m 09.9s) | C | 70 | 17.7 | 377 | 2021-11-25 06:27:53 | MASTER-OAFA | (02h 54m 47.02s , +20d 44m 15.3s) | C | 90 | 17.8 | 496 | 2021-11-25 06:29:42 | MASTER-OAFA | (02h 54m 52.70s , +20d 44m 42.7s) | C | 110 | 18.0 | 636 | 2021-11-25 06:31:52 | MASTER-OAFA | (02h 54m 50.15s , +20d 46m 08.7s) | C | 130 | 17.9 | 800 | 2021-11-25 06:34:21 | MASTER-OAFA | (02h 54m 49.88s , +20d 44m 32.6s) | C | 160 | 17.9 | 990 | 2021-11-25 06:37:21 | MASTER-OAFA | (02h 54m 53.14s , +20d 46m 08.2s) | C | 180 | 18.0 | 1189 | 2021-11-25 06:40:40 | MASTER-OAFA | (02h 54m 46.30s , +20d 45m 18.3s) | C | 180 | 17.9 | 1389 | 2021-11-25 06:44:00 | MASTER-OAFA | (02h 54m 45.76s , +20d 46m 15.8s) | C | 180 | 17.8 | 1588 | 2021-11-25 06:47:19 | MASTER-OAFA | (02h 54m 52.84s , +20d 45m 12.9s) | C | 180 | 17.7 | 1788 | 2021-11-25 06:50:39 | MASTER-OAFA | (02h 54m 46.90s , +20d 44m 09.1s) | C | 180 | 17.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31126 SUBJECT: IceCube-211125A: IceCube observation of a high-energy neutrino candidate track-like event DATE: 21/11/25 16:13:00 GMT FROM: Cristina Lagunas Gualda at DESY The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 21/11/25 at 06:22:21.56 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 1.973 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/135936_74588253.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 21/11/25 Time: 06:22:21.56 UT RA: 43.59 (+ 3.13 - 2.71 deg 90% PSF containment) J2000 Dec: 22.59 (+ 1.54 - 2.53 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. There are two Fermi-LAT 4FGL sources inside the 90% localization region. The nearest source is 4FGL J0248.0+2232, located at RA 42.01 deg and Dec 22.54 deg (J2000), at a distance of 1.46 degrees from the best-fit 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: 31128 SUBJECT: IceCube-211125A: No neutrino counterpart detected with ANTARES DATE: 21/11/26 09:55:17 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 bronze track event IceCube-211125A (GCN #31126 ). The reconstructed origin was 6 degrees below the horizon for ANTARES at the time of the alert. No muon neutrino candidate events were recorded within 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 82.5% of the time window. This leads to a preliminary 90% confidence level upper limit on the muon-neutrino radiant fluence from a point source of about 12 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 35 GeV.cm^-2 (1 - 500 TeV) for an E^-2.5 spectrum. A search over an extended time window of +/- 1 day has also yielded no detection (37% 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: 31132 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-211125A DATE: 21/11/26 18:17:19 GMT FROM: Simone Garrappa at DESY S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and R. de Menezes (Univ. of Wuerzburg, Univ. of Sao Paulo) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC211125A neutrino event (GCN 31126) 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 2021-11-25 at 06:22:21.56 UT (T0) with J2000 position RA = 43.59 (+ 3.13, - 2.71) deg, Decl. = 22.59 (+ 1.54, - 2.53) deg (90% PSF containment). Two cataloged gamma-ray (>100 MeV) sources are located within the 90% IC211125A localization region (4FGL-DR2, The Fermi-LAT collaboration 2020, ApJS, 247, 33). These are 4FGL J0248.0+2232 at 1.46 deg distance, which is associated with the blazar of uncertain type 1RXS J024800.1+223136, and 4FGL J0258.1+2030 at 2.26 deg distance, which is associated with the BL Lac object MG3 J025805+2029. Based on a preliminary analysis of the LAT data over the 1-month timescale before T0, these objects are not significantly detected at gamma-rays. We searched for the existence of intermediate (months 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 IC211125A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC211125A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 2.0e-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 to 2021-11-25 UTC), and < 1.1e-8  ph cm^-2 s^-1 for a 1-month integration time before T0. Due to the current Fermi-LAT observing profile (https://fermi.gsfc.nasa.gov/ssc/observations/types/post_anomaly/) the region of IC211125A is not observable by the LAT since November 12, 2021. Regular monitoring of this region will be resumed at the beginning of December (https://fermi.gsfc.nasa.gov/ssc/observations/timeline/posting/). 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: 31135 SUBJECT: IceCube-211125A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation DATE: 21/11/29 08:20:25 GMT FROM: Volodymyr Savchenko at ISDC,U of Geneve V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland) J. Rodi (IAPS-Roma, Italy) A. Coleiro (APC, France) S. Mereghetti (INAF IASF-Milano, Italy) on behalf of the INTEGRAL multi-messenger collaboration: https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration Using combination of INTEGRAL all-sky detectors (following [1]): SPI/ACS, IBIS/Veto, and IBIS we have performed a search for a prompt gamma-ray counterpart of IceCube-211125A (GCN 31126). At the time of the event (2021-11-25 06:22:21 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 72 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (15% of optimal) response of ISGRI, strongly suppressed (23% of optimal) response of IBIS/Veto, and near-optimal (68% of optimal) response of SPI-ACS. The background within +/-300 seconds around the event was rather stable (excess variance 1.3). We have performed a search for any impulsive events in INTEGRAL SPI- ACS (as described in [2]), IBIS, and IBIS/Veto data. We do not detect any significant counterparts and estimate a 3-sigma upper limit on the 75-2000 keV fluence of 2.8e-07 erg/cm^2 (within the 50% probability containment region of the source localization) for a burst lasting less than 1 s with a characteristic short GRB spectrum (an exponentially cut off power law with alpha=-0.5 and Ep=600 keV) occurring at any time in the interval within 300 s around T0. For a typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and Ep=300 keV), the derived peak flux upper limit is ~2.3e-07 (8.2e-08) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range. We report for completeness and in order of FAP, all excesses identified in the search region. We find: 4 likely background excesses: T-T0 | scale | S/N | flux ( x 1e-06 erg/cm2/s) | FAP -250 | 7.5 | 3.9 | 1.3 +/- 0.282 +/- 0.291 | 0.117 -9.3 | 0.2 | 4 | 0.778 +/- 0.175 +/- 0.175 | 0.147 16.4 | 0.2 | 3.4 | 0.646 +/- 0.175 +/- 0.145 | 0.715 -211 | 0.05 | 7.8 | 3.07 +/- 0.364 +/- 0.689 | 0.979 Note that FAP estimates (especially at timescales above 2s) may be possibly further affected by enhanced non-stationary local background noise. This list excludes any excesses for which FAP is close to unity. AT2021afpi (a possible counterpart to IceCube-211125A) was not recently in INTEGRAL instrument FoV and can not be followed-up due to solar angle constrains. All results quoted are preliminary. This circular is an official product of the INTEGRAL Multi-Messenger team. [1] Savchenko et al. 2017, A&A 603, A46 [2] Savchenko et al. 2012, A&A 541A, 122S //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31143 SUBJECT: IceCube-211125A: Upper limits from a search for additional neutrino events in IceCube DATE: 21/11/29 16:56:38 GMT FROM: Alex Pizzuto at ICECUBE/U of Wisconsin 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-211125A (https://gcn.gsfc.nasa.gov/gcn3/31126.gcn3) in a time range of 1000 seconds centered on the alert event time (2021-11-25 06:14:01.550 UTC to 2021-11-25 06:30:41.550 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-211125A. 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-211125A is 1.4e-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 range between 2e+02 GeV and 8e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2021-11-24 06:22:21.550 UTC to 2021-11-26 06:22:21.550 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-211125A is 1.7e-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: 31153 SUBJECT: IceCube-211125A: No significant detection in HAWC DATE: 21/11/30 16:21:39 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 2021/11/25 06:22:21 UTC, the IceCube collaboration reported a track-like very-high-energy event that has a high probability of being an astrophysical neutrino, IceCube-211125A. Location is at RA: 43.59 (+3.13/-2.71 deg 90% PSF containment) J2000 Dec: 22.59 (+1.54/-2.53 deg 90% PSF containment) J2000 (GCN circular 31126). 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 3.36e-3 (0.34 post-trials), is at RA 44.03 deg, Dec +20.62 deg (±0.10 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 = 2.66e-13 (E/TeV)^-0.3 TeV.cm^-2.s^-1 Search for a transient source. Since the IceCube event fall inside the HAWC field of view, we report on the result for the transit of the IceCube position. Data acquisition started on 2021/11/25 01:54:48 UTC and ended 2021/11/05 08:19:21 UTC. The most significant location, with p-value 3.8e-3 (0.34 post-trials), is at RA 43.07 deg, Dec +23.52 deg (±0.15 deg 68% containment) J2000. We set a time-integrated 95% CL upper limit at the position of maximum significance of: E^2 dN/dE = 1.36e-11 (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.