IceCube-250706A

The IceCube Collaboration (http://icecube.wisc.edu/) reports:

On 25-07-06 at 13:14:40.04 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 0.2382 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/141104_37015490.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 25-07-06
Time: 13:14:40.04 UT
RA: 266.00 (+0.57/-0.59 deg 90% PSF containment) J2000
Dec: 38.97 (+0.49/-0.47 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.

No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of the 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

Noémie Globus (UNAM), Sarah Antier (OCA/IJCLAB), Rosa L. Becerra (U Roma), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), N. A. Rakotondrainibe (LAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM) report:

We observed the field of the IceCube-250706A (GCN 40994
Loading...
 
 ) (goldtrack) event with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico on the night of 2025-07-07 UTC.

COLIBRÍ tiled the IceCube error region, starting at 03:43:42 UTC, e.g T+14.5 h after the trigger, for about 1h distributed over 4 tiles (26x26 arcmin); the maximum exposure at a single sky location was 16x60 s. 

The data were coadded with the COLIBRÍ pipeline and analysed in STDWeb/STDPipe (Karpov 2025). 

Comparing our observations (and after performing image subtraction) against Pan-STARRS DR2, we detect no evident uncatalogued sources within the observed field to a 5-sigma limiting AB magnitude of:

i > 21.6 for the first tile (3 min exp.), centered on (RA, Dec) = (17:43:12.00, +38:46:11.6)
i > 21.1 for the second tile (3 min exp.), centered on (RA, Dec) = (17:43:12.00 +39:10:12.0)	
i >  21.9 for the third tile (16 min exp.), centered on (RA, Dec) = (17:44:48.00, +39:10:12.0)
i > 22.3 for the fourth tile (16 min exp.), centered on (RA, Dec) = (17:44:48.00, +38:46:12.0)

These values are not corrected for the Galactic extinction.

We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams.

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-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 250706.55 (trigger No 37015490,17h 43m 54.48s , +38d 59m 38.4s, R=0.6) errorbox  58565 sec after notice time and 58603 sec after trigger time at 2025-07-07 05:31:23 UT, with upper limit up to  18.5 mag. The observations began at zenith distance = 76 deg. The sun  altitude  is -75.7 deg. 

MASTER-Tavrida robotic telescope  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the IceCube Alert 250706.55 errorbox  1 days 20760 sec after notice time and 1 days 20797 sec after trigger time at 2025-07-07 19:01:17 UT, with upper limit up to  14.9 mag. Observations started at twilight.  The observations began at zenith distance = 16 deg. The sun  altitude  is -13.3 deg. 

The galactic latitude b = 29 deg., longitude l = 65 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2927494

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   58633 | 2025-07-07 05:31:23 |         MASTER-OAFA | (17h 52m 43.98s , +39d 48m 07.5s) |   C |    60 | 17.9 |        
   58693 | 2025-07-07 05:31:23 |         MASTER-OAFA | (17h 52m 43.98s , +39d 48m 07.6s) |   C |   180 | 18.5 |  Coadd 
   58708 | 2025-07-07 05:32:38 |         MASTER-OAFA | (17h 52m 37.32s , +39d 47m 39.5s) |   C |    60 | 17.9 |        
   58782 | 2025-07-07 05:33:52 |         MASTER-OAFA | (17h 52m 36.76s , +39d 48m 41.6s) |   C |    60 | 17.9 |        
   58857 | 2025-07-07 05:35:07 |         MASTER-OAFA | (17h 52m 42.61s , +39d 47m 42.4s) |   C |    60 | 17.9 |        
   58931 | 2025-07-07 05:36:20 |         MASTER-OAFA | (17h 52m 35.82s , +39d 46m 43.9s) |   C |    60 | 17.8 |        
   59005 | 2025-07-07 05:37:34 |         MASTER-OAFA | (17h 52m 41.21s , +39d 47m 10.1s) |   C |    60 | 17.8 |        
  107228 | 2025-07-07 19:01:17 |      MASTER-Tavrida | (17h 43m 55.10s , +39d 01m 11.7s) |   C |    60 | 14.9 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

S. Garrappa (Weizmann Institute of Science), L. Pfeiffer (Univ. of Wuerzburg), S. Buson (DESY, Univ. of Wuerzburg) 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 IC250706A neutrino event (GCN 40994
Loading...
 
 ) 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 2025-07-06 at 13:14:40.04 UTC (T0) with J2000 position RA = 266.00 (+0.57, -0.59) deg, Decl. = 38.97 (+0.49, -0.47) deg 90% PSF containment (J2000). No cataloged gamma-ray sources are found within the 90% IC250706A localization error (4FGL-DR4; The Fourth Fermi-LAT catalog Data Release 4, The Fermi-LAT collaboration 2023, arXiv:2307.12546
Loading...
 
 ).

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 IC250706A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IC250706A best-fit position, the >100 MeV flux upper limit (95% confidence) is <5.0e-10 ph cm^-2 s^-1 for ~16-years (2008-08-04 / T0), <5.0e-09 (<9.2e-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 source, the Fermi-LAT contact person is S. Garrappa (simone.garrappa at weizmann.ac.il).

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.

Q. Y. Wu, Y. Liu (NAO, CAS), G. Gianfagna, A. L. Thakur (INAF-IAPS) on behalf of the Einstein Probe (EP) team:

EP-FXT performed two follow-up observations of the IceCube-250706A (GCN 40994
Loading...
 
 ) (goldtrack) event. The first follow-up observation (obs1) started from 2025-07-06T13:56:24, about 40 minutes after the neutrino trigger, with an exposure time of 5.9 ks. The second one (obs2) started from 2025-07-06T21:01:14, about 8 hours after the trigger, with an exposure time of 4.1 ks. With the 1 deg x 1 deg FoV, EP-FXT covered most part of the 90% C.L. error region of the neutrino event. 

Within the neutrino localization error region, only one source exhibited significant variability compared with historical fluxes or historical upper limits. The details are listed below:
Source: EPF_J174217.4+392257
RA (J2000): 265.5726
Dec (J2000): 39.3826
Position error in radius: 10 arcsec (90% C.L.) 
Flux in obs1: 1 x 10^-12 erg/s/cm2 (0.5-10 keV)
Flux in obs2: not detected, with an upper limit around 5 x 10^-14 erg/s/cm2 (0.5-10 keV)
 
A BY Dra variable star, ZTF J174217.39+392252.1, is 5 arcsec away from EPF_J174217.4+392257. Thus, the significant variability is likely due to the flare of this star with the X-ray luminosity of 6 x 10^30 erg/s.

No other source exhibited significant variability between the two observations. 

Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).

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-250706A (https://gcn.nasa.gov/circulars/40994
Loading...
 
 ) in a time range of 1000 seconds centered on the alert event time (2025-07-06 13:06:20.040 UTC to 2025-07-06 13:23:00.040 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-250706A. We report a p-value of 1.00 in this time window. 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-250706A is 1.5e-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 6e+04 GeV. 

A subsequent search was performed including 2 days of data centered on the alert event time (2025-07-05 13:14:40.040 UTC to 2025-07-07 13:14:40.040 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-250706A is 1.8e-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)

Robert Stein (JSI), Jannis Necker (DESY), Anna Franckowiak (Ruhr University Bochum) and Akshay Eranhalodi (DESY) 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-250706A (Zegarelli et. al, GCN 40994
Loading...
 
 ) 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 2025-07-07 05:03 UTC, approximately 15.8 hours after event time. We covered 67.1% (0.6 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. 

This is consistent with similar non-detections reported by Globus et al. (GCN 41003
Loading...
 
 ) and Becerra et al. (GCN 41004
Loading...
 
 ). 

Observations of this field will continue as part of our standard ToO cadence for high-energy neutrinos (Stein et al. 2023).

Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; University of Wisconsin at Milwaukee, 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, and OKC, University of Stockholm, Sweden. Operations are conducted by Caltech's Optical Observatory (COO), Caltech/IPAC, and the University of Washington at Seattle, USA. 

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 ).

Robert Stein (UMD), Danielle Frostig (CfA), Viraj Karambelkar (Caltech), Mansi Kasliwal (Caltech), Nathan Lourie (MIT), Geoffrey Mo (MIT), and Robert Simcoe (MIT) report:

On behalf of Wide-Field Infra-Red Transient Explorer (WINTER) collaboration: 

We observed the localization region of the neutrino event IceCube-250706A (Zegarelli et. al, GCN 40994
Loading...
 
 ) with the 1.2 sq. degree near-IR WINTER camera on the Palomar 1-m telescope (Lourie et al. 2021, Frostig et al. 2024). We conducted observations in J-band beginning at 2025-07-07 02:42 UTC, approximately 13.5 hours after event time. Our observations covered a total of 0.7 sq. deg. of sky for which reference images were available, corresponding to 77.3% of the total probability. Our observations reached a median depth of 18.8 AB mag. 

The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565
Loading...
 
 ). We use data from the UKIRT Hemisphere survey (Dye et al. 2018) as references for image subtraction. We search for WINTER sources with multiple detections, and for WINTER sources with cross-matches in the alert stream of the Zwicky Transient Facility (Bellm et al. 2019). 

After removing likely stellar sources and likely subtraction artefacts, we find no candidate counterparts.

This is consistent with similar non-detections reported in the optical by Globus et al. (GCN 41003
Loading...
 
 ),  Becerra et al. (GCN 41004
Loading...
 
 ) and Stein et al. (GCN 41040
Loading...
 
 ). 

Observations of this field will continue as part of the WINTER neutrino follow-up program.

WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research.