//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30626 SUBJECT: IceCube Alert 210811.09: Global MASTER-Net observations report DATE: 21/08/11 02:13:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, 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, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (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) was pointed to the IceCube Alert 210811.09 (trigger No 36044887,18h 05m 41.76s , +25d 22m 01.2s, R=0.51) errorbox 48 sec after notice time and 124 sec after trigger time at 2021-08-11 02:04:48 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 57 deg. The sun altitude is -51.3 deg. MASTER-IAC robotic telescope located in Spain (IAC Teide Observatory) was pointed to the IceCube Alert 210811.09 errorbox 51 sec after notice time and 127 sec after trigger time at 2021-08-11 02:04:51 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 56 deg. The sun altitude is -44.5 deg. The galactic latitude b = 20 deg., longitude l = 52 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1687110 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 129 | 2021-08-11 02:04:48 | MASTER-OAFA | (18h 03m 39.02s , +24d 39m 22.3s) | C | 10 | 17.2 | 142 | 2021-08-11 02:04:51 | MASTER-IAC | (18h 05m 06.46s , +25d 19m 43.1s) | P| | 30 | 17.5 | 142 | 2021-08-11 02:04:51 | MASTER-IAC | (18h 04m 11.29s , +25d 25m 52.8s) | P- | 30 | 17.2 | 164 | 2021-08-11 02:05:17 | MASTER-OAFA | (18h 03m 42.19s , +24d 41m 00.0s) | C | 20 | 17.6 | 192 | 2021-08-11 02:05:41 | MASTER-IAC | (18h 05m 06.92s , +25d 20m 44.0s) | P| | 30 | 17.5 | 204 | 2021-08-11 02:05:57 | MASTER-OAFA | (18h 03m 35.66s , +24d 40m 23.7s) | C | 20 | 17.6 | 250 | 2021-08-11 02:06:38 | MASTER-OAFA | (18h 03m 34.86s , +24d 41m 26.7s) | C | 30 | 17.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30627 SUBJECT: IceCube-210811A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 21/08/11 03:53:19 GMT FROM: Marcos Santander at U. Alabama/IceCube The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 21/08/11 at 02:02:44.04 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_GOLD alert stream. The average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 0.694 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/135591_36044887.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 21/08/11 UT Time: 02:02:44.04 RA: 270.79 (+1.07, -1.08 deg 90% PSF containment) J2000 Dec: 25.28 (+0.79, -0.84 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 is one Fermi-LAT 4FGL gamma-ray source located within the 90% error region, 4FGL J1803.3+2425 (RA = 270.84 deg, Dec = 24.43 deg J2000) at a distance of 0.85 deg from the best-fit neutrino 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: 30639 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-210811A DATE: 21/08/12 23:59:33 GMT FROM: Simone Garrappa at DESY S. Garrappa (DESY-Zeuthen), S. Buson (Univ. of Wuerzburg) and R. de Menezes (Univ. of Sao Paulo, Univ. of Wuerzburg) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC210811A neutrino event (GCN 30627) 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 2021-08-11 at 02:02:44.04 UT (T0) with J2000 position RA = 270.79 (+ 1.07, - 1.08) deg, Decl. = 25.28 (+ 0.79, - 0.84) deg (90% PSF containment). One cataloged gamma-ray (>100 MeV) source is located within the 90% IC210811A localization region (4FGL-DR2, The Fermi-LAT collaboration 2020, ApJS, 247, 33). This is the unassociated source 4FGL J1803.3+2425. Based on a preliminary analysis of the LAT data over the timescale of 1-day and 1-month prior to T0, this object is 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 IC210811A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC210811A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 5.3e-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 to 2021-08-11 UTC), and < 5.0e-8 (< 1.3e-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: 30644 SUBJECT: IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility DATE: 21/08/13 15:14:35 GMT FROM: Simeon Reusch at DESY Robert Stein (DESY), Sven Weimann (Ruhr University Bochum), Simeon Reusch (DESY), Jannis Necker (DESY), Anna Franckowiak (DESY/Ruhr University Bochum) and Michael Coughlin (UMN) report, On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: We observed the localization region of the neutrino event IceCube-210811A (Lagunas et. al, GCN 29980) 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 and r-band beginning at 2021-08-12 04:45 UTC, approximately 26.7 hours after event time. We covered 88% (2.7 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. We re-observed the localization area on 2021-08-13 in the g-band with 30s exposure. 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). We looked for high-significance transient candidates with our pipeline, lying within the 90.0% localization of the skymap. No compelling 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. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. 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: 30649 SUBJECT: IceCube-210811A: Upper limits from Fermi-GBM Observations DATE: 21/08/16 21:06:34 GMT FROM: Cori Fletcher at USRA C. Fletcher (USRA) reports on behalf of the Fermi-GBM team: For the IceCube high-energy neutrino candidate event IceCube-210811A (GCN 30627), at the event time Fermi-GBM was observing the reported neutrino location at: RA: 270.79 (+1.07, -1.08 deg 90% PSF containment) J2000 Dec: 25.28 (+0.79, -0.84 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-210811A. 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: 8.7 11. 19. 1.024 s: 2.1 2.7 4.3 8.192 s: 1.1 1.4 1.5 These results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30651 SUBJECT: IceCube-210811A: Upper limits from a search for additional neutrino events in IceCube DATE: 21/08/16 21:24:37 GMT FROM: Alex Pizzuto at ICECUBE/U of Wisconsin The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search for additional track-like muon neutrino events arriving from the direction of IceCube-210811A (https://gcn.gsfc.nasa.gov/gcn3/30627.gcn3) in a time range of 2 days centered on the alert event time (2021-08-10 02:02:44.04 UTC to 2021-08-12 02:02:44.04 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, 4 additional track-like events are found in spatial coincidence with the 90% containment region of IceCube-210811A. We find that these data are consistent with atmospheric background expectations, with a p-value of 1.0. We accordingly derive a time-integrated muon-neutrino flux upper limit at the alert position of E^2 dN/dE = 5.5 x 10^-5 TeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are approximately between 1 TeV and 1 PeV. A subsequent search was performed to include the month of data prior to the alert event (2021-07-12 02:02:44.04 UTC to 2021-08-12 02:02:44.04 UTC). In this case, we report a p-value of 1.0, consistent with no significant excess of track-like events, and a corresponding time-integrated muon-neutrino flux upper limit assuming an E^-2 spectrum (E^2 dN/dE) of 5.7 x 10^-5 TeV cm^-2 at the 90% CL. 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.