//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31985 SUBJECT: IceCube Alert 220501.95: Global MASTER-Net observations report DATE: 22/05/01 23:26:16 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, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the IceCube Alert 220501.95 (trigger No 56014830,20h 46m 45.74s , +18d 42m 41.4s, R=0.5134) errorbox 1614 sec after notice time and 1669 sec after trigger time at 2022-05-01 23:18:47 UT, with upper limit up to 15.9 mag. The observations began at zenith distance = 61 deg. The sun altitude is -26.6 deg. The galactic latitude b = -15 deg., longitude l = 64 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1960533 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1699 | 2022-05-01 23:18:47 | MASTER-Tavrida | (20h 45m 06.21s , +18d 22m 30.4s) | C | 60 | 15.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31986 SUBJECT: IceCube-220501A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 22/05/02 00:28:05 GMT FROM: Marcos Santander at U. Alabama/IceCube The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2022-05-01 at 22:50:58.64 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 2.110 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/136588_56014830.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2022-05-01 Time: 22:50:58.64 UT RA: 311.57 (+0.82, -1.07 deg 90% PSF containment) J2000 Dec: 18.68 (+1.08, -0.92 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 no known gamma-ray sources in the 90% containment region for the event. The nearest source in the 4FGL-DR3 Fermi-LAT catalog is 4FGL J2043.3+1711 (310.84 deg, 17.19 deg J2000, 1.65 deg away from the best-fit neutrino candidate position). 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: 31989 SUBJECT: IceCube-220501A: No Candidate Counterparts from the Zwicky Transient Facility DATE: 22/05/02 17:44:11 GMT FROM: Jannis Necker at DESY Robert Stein (Caltech), Sven Weimann (Ruhr University Bochum), Simeon Reusch (DESY), Jannis Necker (DESY) and Anna Franckowiak (DESY/Ruhr University Bochum), On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: As part of the ZTF neutrino follow up program (Stein et al. 2022), we observed the localization region of the neutrino event IceCube-220501A (Santander et. al, GCN 31986) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g-band beginning at 2022-05-02 09:39 UTC, approximately 10.8 hours after event time. We covered 87% (2.5 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019). No candidate counterparts were detected. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA; WIS, Israel; OKC, Sweden; JSI/UMd, USA; DESY, Germany; TANGO, Taiwan; UW Milwaukee, USA; LANL, USA; TCD, Ireland; IN2P3, France. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019). Alert filtering is performed with the AMPEL Follow-up Pipeline (Stein et al. 2021). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31992 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-220501A DATE: 22/05/02 21:00:04 GMT FROM: Simone Garrappa at DESY S. Garrappa (DESY-Zeuthen) and S. Buson (Univ. of Wuerzburg) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC220501A neutrino event (GCN 31986) 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 2022-05-01 at 22:50:58.64 UT (T0) with J2000 position RA = 311.57 (+0.82, -1.07) deg, Decl. = +18.68 (+1.08, -0.92) deg (90% PSF containment). No cataloged gamma-ray (>100 MeV) sources are located within the 90% IC220501A localization region (4FGL-DR3; arXiv:2201.11184; The Fermi-LAT collaboration 2020, ApJS, 247, 33). 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 IC220501A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC220501A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 5e-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 to 2022-05-01 UTC), and < 9e-9 (< 7e-8) 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: 31994 SUBJECT: IceCube-220501A: Upper limits from a search for additional neutrino events in IceCube DATE: 22/05/03 16:45:37 GMT FROM: Abhishek Desai 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-220501A (https://gcn.gsfc.nasa.gov/gcn3/31986.gcn3) in a time range of 1000 seconds centered on the alert event time (2022-05-01 22:42:38.635 UTC to 2022-05-01 22:59:18.635 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-220501A. 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-220501A 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 energy range between 2e+02 GeV and 9e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2022-04-30 22:50:58.635 UTC to 2022-05-02 22:50:58.635 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-220501A ranges from 1.6e-01 to 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)