//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31944 SUBJECT: IceCube-220425A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 22/04/25 04:08:40 GMT FROM: Marcos Santander at U. Alabama/IceCube The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2022-04-25 at 02:44:57.82 UT IceCube detected a track-like event which was selected by the ICECUBE_Astrotrack_GOLD alert stream. We note that, while the average astrophysical neutrino purity for Gold alerts is 50%, this event has a lower probability (~17%). This alert has an estimated false alarm rate of 0.576 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/136568_17854328.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2022-04-25 Time: 02:44:57.82 UT RA: 268.24 (+1.98, -1.66 deg 90% PSF containment) J2000 Dec: -10.73 (+1.71, -1.48 deg 90% PSF containment) J2000 One gamma-ray source listed in the 4FGL-DR3 Fermi-LAT catalog is located within the 90% containment region for the neutrino event. The source is 4FGL J1752.6-1010 (RA: 268.16 deg, Dec: -10.18 deg J2000), 0.56 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: 31946 SUBJECT: IceCube Alert 220425.11: Global MASTER-Net observations report DATE: 22/04/25 07:26:17 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-OAGH robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) started inspect of the IceCube Alert 220425.11 (trigger No 17854328,17h 53m 29.76s , -12d 18m 36.0s, R=1.11) errorbox 13769 sec after notice time and 13813 sec after trigger time at 2022-04-25 06:35:11 UT, with upper limit up to 17.6 mag. The observations began at zenith distance = 76 deg. The sun altitude is -44.8 deg. The galactic latitude b = 6 deg., longitude l = 16 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1953585 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 13844 | 2022-04-25 06:35:11 | MASTER-OAGH | (17h 48m 57.35s , -12d 30m 38.1s) | C | 60 | 17.3 | 13844 | 2022-04-25 06:35:11 | MASTER-OAGH | (17h 48m 17.45s , -12d 06m 51.7s) | C | 60 | 16.8 | 14127 | 2022-04-25 06:39:55 | MASTER-OAGH | (17h 56m 25.28s , -12d 06m 59.5s) | C | 60 | 16.4 | 14127 | 2022-04-25 06:39:55 | MASTER-OAGH | (17h 57m 05.48s , -12d 30m 44.6s) | C | 60 | 16.9 | 14888 | 2022-04-25 06:52:36 | MASTER-OAGH | (17h 48m 56.31s , -12d 29m 39.0s) | C | 60 | 17.5 | 14888 | 2022-04-25 06:52:36 | MASTER-OAGH | (17h 48m 17.87s , -12d 05m 50.4s) | C | 60 | 16.7 | 15133 | 2022-04-25 06:56:40 | MASTER-OAGH | (17h 56m 26.76s , -12d 06m 38.8s) | C | 60 | 16.7 | 15133 | 2022-04-25 06:56:40 | MASTER-OAGH | (17h 57m 05.52s , -12d 30m 28.9s) | C | 60 | 17.4 | 16107 | 2022-04-25 07:12:54 | MASTER-OAGH | (17h 48m 19.85s , -12d 05m 02.3s) | C | 60 | 15.9 | 16107 | 2022-04-25 07:12:54 | MASTER-OAGH | (17h 48m 56.45s , -12d 28m 52.4s) | C | 60 | 17.6 | 16552 | 2022-04-25 07:20:20 | MASTER-OAGH | (17h 56m 25.20s , -12d 07m 12.1s) | C | 60 | 15.6 | 16552 | 2022-04-25 07:20:20 | MASTER-OAGH | (17h 57m 01.27s , -12d 30m 45.5s) | C | 60 | 16.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31948 SUBJECT: IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate DATE: 22/04/25 15:44:17 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs K.Zhirkov, V.Lipunov, E.Gorbovskoy, G.Antipov, D.Vlasenko, A.Kuznetsov, N.Tyurina, P.Balanutsa, A.Chasovnikov, D.Kuvshinov, V.Topolev,Ya.Kechin, Yu.Tselik, K.Minkina (Lomonosov Moscow State University, SAI, Physics Department), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), N.M.Budnev, O.Gress, (ISU,API), C.Francile, R. Podesta, C.Lopez, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA), D.A.H.Buckley (SAAO), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), V.Senik, A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-OAGH was the first telescope of MASTER-NET to observe IC-220425's error-box at 2022-04-25 06:35:11 UTC, 13813 sec after the trigger (Lipunov et al., GCN #31946). We report on the detection of a flaring blazar TXS 1742-078 (RA=266.3629 Dec=-7.8844). IC-220425A is a track-like event with an estimated energy of 600 TeV and signalness of 17%. It was detected at 2022-04-25 02:44:58 UTC and is centred at RA=268.24 (+1.98, -1.66 deg, 90% PSF containment), Dec=-10.73 (+1.71, -1.48 deg, 90% PSF containment) J2000(GCN #31944). The first image of TXS 1742-078 was obtained at 2022:04-25 06:36:32 UTC. It is located 3.4 deg away from the center of error-box. Based on our photometry, the blazar is currently experiencing a flaring episode (W=17.3+/-0.1, no correction for extinction), compared to its quiscence state (W=19.2+/-0.3). Judging from ATLAS observations(Smith et al, PASP 132, 2020)(https://fallingstar-data.com/forcedphot/queue/195704/plot.pdf) it is 31944the brightest flare since 2017. Interestingly enough, after the correction for galactic extinction(Schlafly and Finkbeiner, 2011) (A_V=3.18), magnitude of TXS 1742-078 (W=14.1+/-0.1) is close to that of TXS 0506+056 during IC-170922A (W=14.3, no correction for extinction). Judging from these facts, we highly encourage multiwavelength observations to determine whether or not this blazar is a source of IC-220425A The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31953 SUBJECT: Fermi-LAT Gamma-ray Observations of IceCube-220425A DATE: 22/04/26 17:08:51 GMT FROM: Sara Buson at GSFC/Fermi S. Buson (Univ. of Wuerzburg), S. Garrappa (DESY-Zeuthen) and G. La Mura (LIP) on behalf of the Fermi-LAT collaboration: We report an analysis of observations of the vicinity of the high-energy IC220425A neutrino event (GCN 31944) 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 2022-04-25 at 02:44:57.82 UT (T0) with J2000 position RA = 268.24 (+1.98, -1.66) deg, Decl. = -10.73 (+1.71, -1.48) deg (90% PSF containment). One cataloged gamma-ray (>100 MeV) source is located within the 90% IC220425A localization region (4FGL-DR3; arXiv:2201.11184; The Fermi-LAT collaboration 2020, ApJS, 247, 33). This is the gamma-ray source 4FGL J1752.6-1010. Based on a preliminary analysis of the LAT data over the timescales of 1-day and 1-month prior to T0, this object is not significantly detected (> 5 sigma). 4FGL J1752.6-1010 is associated with the flat-spectrum radio object TXS 1749-101 (a.k.a. IVS B1749-101). It has been proposed as promising neutrino emitter candidate by Plavin et al. (2020 ApJ, 894, 101), and tentatively associated with a previously observed EHE IceCube event, i.e. IC181023A (GCN 23375, GCN 23378). The latter was detected by the IceCube Observatory on 2018-10-23 16:37:32.65 UTC (T0) with J2000 position RA = 270.18 (-1.70,+2.00) deg, Decl. = -8.57 (-1.30,+1.25) deg 90% PSF containment. 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 IC220425A best-fit position. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC220425A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 3.1e-10 ph cm^-2 s^-1 for ~13-years (2008-08-04 to 2022-04-25 UTC), and < 1.3e-8 (< 2.9e-7) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0. Outside the neutrino IC220425A 90% PSF containment lies the gamma-ray source 4FGL J1745.4-0753, a.k.a. 3FHL J1745.4-0752 (The Fermi-LAT collaboration 2014, AAS, 223, 256) and TXS 1742-078. TXS 1742-078 is currently undergoing an enhanced optical state (Zhitkov. et al. 2022, GCN 31948). Based on a preliminary analysis of the LAT data over the timescales of 1-day and 1-month prior to T0, this object is not significantly detected (> 5 sigma). 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31971 SUBJECT: IceCube-220425A: Upper limits from a search for additional neutrino events in IceCube DATE: 22/04/29 16:22:38 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-220425A (https://gcn.gsfc.nasa.gov/gcn3/31944.gcn3) in a time range of 1000 seconds centered on the alert event time (2022-04-25 02:36:37.820 UTC to 2022-04-25 02:53:17.820 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-220425A. 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-220425A ranges from 1.2e+00 to 2.2e+00 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 5e+02 GeV and 1e+06 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2022-04-24 02:44:57.820 UTC to 2022-04-26 02:44:57.820 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-220425A ranges from 1.1e+00 to 2.3e+00 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)