IceCube-260111A
GCN Circular 43397
Subject
Fermi-LAT Gamma-ray Observations of IceCube-260111A
Date
2026-01-14T12:42:22Z (2 months ago)
From
Leo Pfeiffer at University of Würzburg <pfeiffer.leo@gmail.com>
Via
Web form
L. Pfeiffer (Univ. of Wuerzburg), S. Buson (DESY, Univ. of Wuerzburg) and S. Garrappa (Weizmann Institute of Science) on behalf of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the high-energy IC-260111A neutrino event (GCN 43374) 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 26-01-11 at 20:10:33.91 UTC (T0) with J2000 position RA = 70.88 (+1.55, -1.40) deg, Decl. = 34.59 (+0.76, -0.64 ) deg 90% PSF containment. One cataloged >100 MeV gamma-ray source is located within the 90% IC-260111A localization error, at a distance of roughly 0.3 deg (Fourth Fermi-LAT catalog, 4FGL-DR4, The Fermi-LAT collaboration 2023, arXiv:2307.12546). This is the object 4FGL J0444.6+3425 associated with the blazar of uncertain type B2 0441+34. Based on a preliminary analysis of the LAT data over the timescale of one day and one month prior T0, this object is not significantly detected at gamma-rays.
We searched for the existence of intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (>5sigma) new excess emission (> 100 MeV) within the IC-260111A 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 3.0e-10 ph cm^-2 s^-1 for ~17-years (2008-08-04 / T0), <9.3e-09 (1.6 e-07) 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 this analysis, the Fermi-LAT contact person is L. Pfeiffer (leonard.pfeiffer 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.
GCN Circular 43393
Subject
IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
Date
2026-01-13T20:32:34Z (2 months ago)
From
Alicia Mand at IceCube/UW-Madison <aemand@wisc.edu>
Via
Web form
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-260111A (https://gcn.nasa.gov/circulars/43374) in a time range of 1000 seconds centered on the alert event time (2026-01-11 20:02:13.888 UTC to 2026-01-11 20:18:53.888 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-260111A. We report a p-value of 1.00 in this time window. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, is 1.4e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260111A 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 6e+04 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2026-01-10 20:10:33.888 UTC to 2026-01-12 20:10:33.888 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. IceCube’s sensitivity to neutrino point sources with an E^-2.5 spectrum, expressed as E^2 dN/dE evaluated at 1 TeV, ranges from 1.6e-01 to 1.7e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260111A 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)
GCN Circular 43374
Subject
IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
Date
2026-01-11T22:48:41Z (2 months ago)
From
Giacomo Sommani at Ruhr-Universität Bochum <gsommani@icecube.wisc.edu>
Via
Web form
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
On 26-01-11 at 20:10:33.91 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 0.7434 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/141893_3811884.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:
Date: 26-01-11
Time: 20:10:33.91 UT
RA: 70.88 (+1.55/-1.4 deg 90% PSF containment) J2000
Dec: 34.59 (+0.76/-0.64 deg 90% PSF containment) J2000
One gamma-ray source from the Fermi 4FGL-DR4 catalog is located within the 90% uncertainty region of this event: 4FGL J0444.6+3425, at RA = 71.16° and Dec = 34.42° (J2000), with an angular separation of 0.29° from the best-fit event 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
GCN Circular 43373
Subject
IceCube Alert 260111A: Global MASTER-Net observations report
Date
2026-01-11T20:39:22Z (2 months ago)
Edited On
2026-01-12T14:50:11Z (2 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Vladimir Lipunov at Lomonosov Moscow State University <lipunov@sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A.Sosnovskij (CrAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the IceCube Alert 260111.84 (trigger No 3811884,04h 44m 30.72s , +35d 03m 43.2s, R=0.51) errorbox 12 sec after notice time and 58 sec after trigger time at 2026-01-11 20:11:32 UT, with upper limit up to 19.2 mag. The observations began at zenith distance = 21 deg. The sun altitude is -64.6 deg.
MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the IceCube Alert 260111.84 errorbox 26 sec after notice time and 72 sec after trigger time at 2026-01-11 20:11:46 UT, with upper limit up to 14.1 mag. The observations began at zenith distance = 61 deg. The sun altitude is -44.9 deg.
MASTER-SAAO robotic telescope located in South Africa (South African Astronomical Observatory) was pointed to the IceCube Alert 260111.84 errorbox 61 sec after notice time and 107 sec after trigger time at 2026-01-11 20:12:21 UT, with upper limit up to 18.9 mag. The observations began at zenith distance = 67 deg. The sun altitude is -24.8 deg.
The galactic latitude b = -6 deg., longitude l = 168 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3100219
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
64 | 2026-01-11 20:11:32 | MASTER-Kislovodsk | (04h 43m 04.86s , +35d 34m 12.2s) | P| | 10 | 15.9 |
64 | 2026-01-11 20:11:32 | MASTER-Kislovodsk | (04h 43m 29.08s , +35d 12m 14.1s) | C | 10 | 16.9 |
89 | 2026-01-11 20:11:32 | MASTER-Kislovodsk | (04h 43m 29.08s , +35d 12m 14.1s) | C | 60 | 18.0 | Coadd
78 | 2026-01-11 20:11:46 | MASTER-Tunka | (04h 43m 38.90s , +35d 16m 36.1s) | P- | 10 | 14.1 |
78 | 2026-01-11 20:11:46 | MASTER-Tunka | (04h 43m 07.38s , +35d 23m 28.3s) | P| | 10 | 13.0 |
99 | 2026-01-11 20:12:02 | MASTER-Kislovodsk | (04h 43m 04.82s , +35d 34m 09.7s) | P| | 20 | 16.4 |
99 | 2026-01-11 20:12:02 | MASTER-Kislovodsk | (04h 43m 29.04s , +35d 12m 12.1s) | C | 20 | 17.4 |
118 | 2026-01-11 20:12:21 | MASTER-SAAO | (04h 42m 05.60s , +34d 48m 35.2s) | C | 20 | 18.0 |
153 | 2026-01-11 20:12:21 | MASTER-SAAO | (04h 42m 05.60s , +34d 48m 35.2s) | C | 90 | 18.9 |
118 | 2026-01-11 20:12:21 | MASTER-SAAO | (04h 40m 03.11s , +35d 04m 27.6s) | C | 20 | 17.8 |
153 | 2026-01-11 20:12:21 | MASTER-SAAO | (04h 40m 03.11s , +35d 04m 27.6s) | C | 90 | 18.8 |
145 | 2026-01-11 20:12:43 | MASTER-Kislovodsk | (04h 43m 28.95s , +35d 12m 09.1s) | C | 30 | 17.8 |
145 | 2026-01-11 20:12:43 | MASTER-Kislovodsk | (04h 43m 04.76s , +35d 34m 06.1s) | P| | 30 | 17.0 |
162 | 2026-01-11 20:13:01 | MASTER-SAAO | (04h 42m 05.86s , +34d 48m 37.9s) | C | 30 | 18.3 |
162 | 2026-01-11 20:13:01 | MASTER-SAAO | (04h 40m 03.42s , +35d 04m 31.2s) | C | 30 | 18.2 |
200 | 2026-01-11 20:13:33 | MASTER-Kislovodsk | (04h 43m 04.72s , +35d 34m 02.5s) | P| | 40 | 16.9 |
200 | 2026-01-11 20:13:33 | MASTER-Kislovodsk | (04h 43m 28.88s , +35d 12m 06.2s) | C | 40 | 17.9 |
255 | 2026-01-11 20:13:33 | MASTER-Kislovodsk | (04h 43m 28.89s , +35d 12m 06.1s) | C | 150 | 18.7 | Coadd
216 | 2026-01-11 20:13:49 | MASTER-SAAO | (04h 42m 06.14s , +34d 48m 40.7s) | C | 40 | 18.4 |
216 | 2026-01-11 20:13:50 | MASTER-SAAO | (04h 40m 03.68s , +35d 04m 34.5s) | C | 40 | 18.2 |
265 | 2026-01-11 20:14:33 | MASTER-Kislovodsk | (04h 43m 04.64s , +35d 33m 58.2s) | P| | 50 | 17.1 |
265 | 2026-01-11 20:14:33 | MASTER-Kislovodsk | (04h 43m 28.78s , +35d 12m 02.4s) | C | 50 | 18.0 |
280 | 2026-01-11 20:14:49 | MASTER-SAAO | (04h 42m 06.49s , +34d 48m 43.7s) | C | 50 | 18.5 |
280 | 2026-01-11 20:14:49 | MASTER-SAAO | (04h 40m 03.97s , +35d 04m 38.1s) | C | 50 | 18.4 |
341 | 2026-01-11 20:15:44 | MASTER-Kislovodsk | (04h 43m 28.69s , +35d 11m 58.8s) | C | 60 | 18.2 |
341 | 2026-01-11 20:15:44 | MASTER-Kislovodsk | (04h 43m 04.53s , +35d 33m 54.1s) | P| | 60 | 17.4 |
354 | 2026-01-11 20:15:58 | MASTER-SAAO | (04h 42m 06.82s , +34d 48m 46.7s) | C | 60 | 18.8 |
354 | 2026-01-11 20:15:58 | MASTER-SAAO | (04h 40m 04.29s , +35d 04m 41.7s) | C | 60 | 18.5 |
432 | 2026-01-11 20:17:05 | MASTER-Kislovodsk | (04h 43m 04.39s , +35d 33m 49.7s) | P| | 80 | 17.4 |
432 | 2026-01-11 20:17:05 | MASTER-Kislovodsk | (04h 43m 28.56s , +35d 11m 55.0s) | C | 80 | 18.4 |
542 | 2026-01-11 20:17:05 | MASTER-Kislovodsk | (04h 43m 28.56s , +35d 11m 54.9s) | C | 300 | 19.2 | Coadd
433 | 2026-01-11 20:17:17 | MASTER-SAAO | (04h 42m 07.12s , +34d 48m 50.4s) | C | 60 | 18.7 |
433 | 2026-01-11 20:17:17 | MASTER-SAAO | (04h 40m 04.61s , +35d 04m 45.6s) | C | 60 | 18.6 |
513 | 2026-01-11 20:18:36 | MASTER-SAAO | (04h 42m 07.48s , +34d 48m 53.0s) | C | 60 | 18.8 |
513 | 2026-01-11 20:18:36 | MASTER-SAAO | (04h 40m 04.97s , +35d 04m 48.8s) | C | 60 | 18.6 |
552 | 2026-01-11 20:18:56 | MASTER-Kislovodsk | (04h 43m 28.37s , +35d 11m 50.5s) | C | 100 | 18.4 |
552 | 2026-01-11 20:18:56 | MASTER-Kislovodsk | (04h 43m 04.21s , +35d 33m 44.7s) | P| | 100 | 17.6 |
592 | 2026-01-11 20:19:55 | MASTER-SAAO | (04h 42m 07.81s , +34d 48m 55.7s) | C | 60 | 18.8 |
592 | 2026-01-11 20:19:55 | MASTER-SAAO | (04h 40m 05.29s , +35d 04m 51.9s) | C | 60 | 18.6 |
683 | 2026-01-11 20:20:56 | MASTER-Kislovodsk | (04h 43m 04.05s , +35d 33m 39.6s) | P| | 120 | 17.6 |
683 | 2026-01-11 20:20:56 | MASTER-Kislovodsk | (04h 43m 28.20s , +35d 11m 46.1s) | C | 120 | 18.4 |
671 | 2026-01-11 20:21:14 | MASTER-SAAO | (04h 42m 08.14s , +34d 48m 58.6s) | C | 60 | 18.8 |
671 | 2026-01-11 20:21:14 | MASTER-SAAO | (04h 40m 05.62s , +35d 04m 55.0s) | C | 60 | 18.7 |
750 | 2026-01-11 20:22:33 | MASTER-SAAO | (04h 42m 08.48s , +34d 49m 01.7s) | C | 60 | 18.8 |
750 | 2026-01-11 20:22:33 | MASTER-SAAO | (04h 40m 05.95s , +35d 04m 58.4s) | C | 60 | 18.6 |
833 | 2026-01-11 20:23:27 | MASTER-Kislovodsk | (04h 43m 27.94s , +35d 11m 41.5s) | C | 120 | 18.5 |
840 | 2026-01-11 20:23:33 | MASTER-Kislovodsk | (04h 43m 03.83s , +35d 33m 33.8s) | P| | 120 | 17.8 |
829 | 2026-01-11 20:23:52 | MASTER-SAAO | (04h 42m 08.82s , +34d 49m 04.0s) | C | 60 | 18.8 |
829 | 2026-01-11 20:23:52 | MASTER-SAAO | (04h 40m 06.27s , +35d 05m 01.0s) | C | 60 | 18.6 |
981 | 2026-01-11 20:25:54 | MASTER-Kislovodsk | (04h 43m 03.62s , +35d 33m 28.6s) | P| | 120 | 17.6 |
981 | 2026-01-11 20:25:54 | MASTER-Kislovodsk | (04h 43m 27.69s , +35d 11m 36.9s) | C | 120 | 18.4 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp.
http : // www.pereplet.ru/lipunov/625.html