GCN 45266: Fermi-LAT Gamma-ray Observations of IceCube-260722A
2026-08-01T07:03:30.575Z | rev 0
L. Pfeiffer (Univ. of Wuerzburg), S. Buson (DESY, Univ. of Wuerzburg), S. Garrappa (Weizmann Institute of Science) and C. Bartolini (INFN Bari) on behalf of the Fermi-LAT collaboration:
We report an analysis of observations of the vicinity of the high-energy IC260722A neutrino event (GCN 45194) 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 2026-07-22 at 06:58:22.82 UTC (T0) with J2000 position RA = 190.55 (+1.03, -1.33) deg, Decl. = 31.0 (+0.67, -0.64) deg 90% PSF containment (J2000). No cataloged gamma-ray sources are found within the 90% IC260722A localization error (FL16Y, The Fermi-LAT 16 Year Source List, The Fermi-LAT collaboration 2026, arXiv:2602.22148).
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 IC260722A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC260722A best-fit position, the >100 MeV flux upper limit (95% confidence) is < 1.8e-10 ph cm^-2 s^-1 for ~18-years (2008-08-04 / T0), <4.0e-09 (<4.6e-08) 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 45217: IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
2026-07-26T15:58:08.984Z | rev 0
Robert Stein (UMD/JSI/NASA GSFC), Avinash Singh (Stockholm), and Jesper Sollerman (Stockholm) report:
We observed ZTF26abjbxfs / SN 2026vts, reported as a possible counterpart (Necker et al., GCN 45198) to IceCube-260722A (Zilleruelo Cañas et. al, GCN 45194).
We obtained spectroscopic observations using the Alhambra Faint Object Spectrograph and Camera (ALFOSC) on the Nordic Optical Telescope (NOT), beginning at 2026-07-24 21:14:1 UTC. Data were reduced using PypeIt (Prochaska et al. 2020).
The spectrum matches well to templates of a Type Ia supernova, and the transient is therefore unrelated to the neutrino. The spectrum is available on TNS.
The data presented here were obtained with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOT.
GCN 45199: IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
2026-07-23T18:29:07.725Z | rev 0
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-260722A (https://gcn.nasa.gov/circulars/45194) in a time range of 1000 seconds centered on the alert event time (2026-07-22 06:50:02.828 UTC to 2026-07-22 07:06:42.828 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-260722A. 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-260722A 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 7e+04 GeV.
A subsequent search was performed including 2 days of data centered on the alert event time (2026-07-21 06:58:22.828 UTC to 2026-07-23 06:58:22.828 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, is 1.6e-01 GeV cm^-2 within the 90% spatial containment region of IceCube-260722A 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 45198: IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
2026-07-23T18:22:44.134Z | rev 0
Jannis Necker (Leiden University), Akshay Eranhalodi (DESY), Robert Stein (JSI), Cristobal Zilleruelo Cañas (DESY), and Anna Franckowiak (Ruhr University Bochum) report,
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. 2023), we observed the localization region of the neutrino event IceCube-260722A (Zilleruelo Cañas et. al, GCN 45194) 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- and r-band beginning at 2026-07-23 04:54 UTC, approximately 21.9 hours after event time. We covered 88.8% (2.3 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). We are left with the following high-significance transient candidate by our pipeline, lying within the 90.0% localization of the skymap.
+--------------------------------------------------------------------------------+
| ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr |
+--------------------------------------------------------------------------------+
| ZTF26abjbxfs | AT 2026vts | 191.3022538 | +30.5970446 | r | 19.78 | 0.07 |
+--------------------------------------------------------------------------------+
ZTF26abjbxfs / AT 2026vts was first detected on 2026-07-23, and is very blue (g-r = -0.2). It appears to lie on the edge of galaxy SDSS J124512.84+303550.1, with a spectroscopic redshift of z=0.0978. Assuming that this is the redshift of the transient, it has a current absolute magnitude of M=-18.8. ATLAS forced photometry reveals two marginal (3 sigma) detections in the ATLAS o-band at m= 19.6 +/- 0.2 mag, 3-4 days before the ZTF observations. This suggests that the transient is still blue more than four days after first detection.
We encourage spectroscopic follow-up to determine its nature and assess potential high-energy neutrino emission scenarios.
Further monitoring of this field will continue as part of the ZTF neutrino follow-up program (Stein et al. 2023)
ZTF and GROWTH are worldwide collaborations comprising Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan; OKC, Sweden; DZA, Germany.
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 nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ).
GCN 45197: IceCube Alert 260722A: Global MASTER-Net observations report
2026-07-22T17:40:06.113Z | rev 3
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),
M. Segura, 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) was pointed to the IceCube Alert 260722A (trigger No 47091427,12h 42m 12.00s , +31d 00m 00.0s, R=0.81) errorbox 36132 sec after notice time and 36189 sec after trigger time at 2026-07-22 17:01:32 UT, with upper limit up to 17.6 mag. Observations started at twilight. The observations began at zenith distance = 69 deg. The sun altitude is -14.7 deg.
The galactic latitude b = 86 deg., longitude l = 145 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3438005
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
36220 | 2026-07-22 17:01:32 | MASTER-SAAO | (12h 41m 27.72s , +31d 36m 07.3s) | C | 60 | 17.6 |
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
GCN 45197: IceCube Alert 260722A: Global MASTER-Net observations report
2026-07-22T17:40:06.113Z | rev 3
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),
M. Segura, 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) was pointed to the IceCube Alert 260722A (trigger No 47091427,12h 42m 12.00s , +31d 00m 00.0s, R=0.81) errorbox 36132 sec after notice time and 36189 sec after trigger time at 2026-07-22 17:01:32 UT, with upper limit up to 17.6 mag. Observations started at twilight. The observations began at zenith distance = 69 deg. The sun altitude is -14.7 deg.
The galactic latitude b = 86 deg., longitude l = 145 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3438005
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
36220 | 2026-07-22 17:01:32 | MASTER-SAAO | (12h 41m 27.72s , +31d 36m 07.3s) | C | 60 | 17.6 |
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
GCN 45194: IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
2026-07-22T08:50:23.524Z | rev 0
The IceCube Collaboration (http://icecube.wisc.edu/) reports:
On 26-07-22 at 06:58:22.82 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.
Documentation regarding the alert streams and their astrophysical purity can be found here: https://gcn.nasa.gov/missions/icecube.
This alert has an estimated false alarm rate of 1.4973 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/142900_47091427.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:
Date: 26-07-22
Time: 06:58:22.82 UT
RA: 190.55 (+1.03/-1.33 deg 90% PSF containment) J2000
Dec: 31.0 (+0.67/-0.64 deg 90% PSF containment) J2000
As announced in GCN Circular 43419 (https://gcn.nasa.gov/circulars/43419), IceCube alert notices for high-energy track alerts are now also streamed via Kafka.
IceCube Gold/Bronze track alerts are available on the Kafka topic 'gcn.notices.icecube.gold_bronze_track_alerts'.
The probability distribution of the true neutrino direction, allowing the extraction of precise 90% containment regions around the best-fit direction, is now available for revised reconstruction of high-energy track alerts.
The corresponding sky map is distributed as a FITS file and follows the explicit naming convention IceCube-YYMMDDX, where YYMMDD indicates the date of the event and X is a letter distinguishing multiple alerts on the same day. The download link is provided through the GCN schema distributed via Kafka.
Detailed documentation describing the alert distribution, schemas, and probability maps is available at: https://gcn.nasa.gov/missions/icecube.
No known gamma-ray sources listed in the Fermi LAT 16-year Source List (FL16Y) are located within the 90% uncertainty region of this event.
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