IceCube-250708A

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-250708A (Zegarelli et. al, GCN 41039
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 ) 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 2025-07-09 02:42 UTC, approximately 12.6 hours after event time. Our observations covered a total of 0.8 sq. deg. of sky for which reference images were available, corresponding to 89.9% of the total probability. Our observations reached a median depth of 18.7 mag AB. 

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
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 ). 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.

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.

Jannis Necker (DESY), Akshay Eranhalodi (DESY), Robert Stein (JSI) 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-250708A (Zegarelli et. al, GCN 41039
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 ) 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 2025-07-09 04:37 UTC, approximately 14.5 hours after event time. We covered 82.2% (0.7 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. 
 
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.

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| ZTF Name     | IAU Name  | RA (deg)    | DEC (deg)   | Filter | Mag   | MagErr |
+--------------------------------------------------------------------------------+
| ZTF25abanmjp |  -------  | 222.4281885 | +26.5431350 | r      | 20.63 | 0.13   |  
+--------------------------------------------------------------------------------+

ZTF25abanmjp was first detected on 2025-06-10. It is nuclear, with a WISE-detected host (W1-W2=0.58). With these colours, this galaxy is a likely AGN. These detections are brighter than archival PS1 photometry of this galaxy (g=22.1, r=21.5), indicating an elevated flux level. However, forced potometry at this position reveals many previous detections at this position in ZTF data over the past six months, with no obvious flaring activity at the time of the neutrino. We conclude that ZTF25abanmjp likely arises from AGN variability. Given the lack of obvious flaring at the time of the neutrino, we have no reason to think that ZTF25abanmjp is associated with IC250708A based on our observations. 

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 ).

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-250708A (https://gcn.nasa.gov/circulars/41039
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 ) in a time range of 1000 seconds centered on the alert event time (2025-07-08 13:56:59.540 UTC to 2025-07-08 14:13:39.540 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-250708A. 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-250708A is 1.4e-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 7e+04 GeV. 

A subsequent search was performed including 2 days of data centered on the alert event time (2025-07-07 14:05:19.540 UTC to 2025-07-09 14:05:19.540 UTC). In this case, we report a p-value of 0.02, 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-250708A is 1.7e-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)

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

On 25-07-08 at 14:05:19.54 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 1.6259 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/141112_11292662.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 25-07-08
Time: 14:05:19.54 UT
RA: 222.71 (+0.52/-0.54 deg 90% PSF containment) J2000
Dec: 26.49 (+0.47/-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

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-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the IceCube Alert 250708.59 (trigger No 11292662,14h 52m 41.28s , +26d 45m 18.0s, R=0.51) errorbox  10955 sec after notice time and 11017 sec after trigger time at 2025-07-08 17:08:56 UT, with upper limit up to  18.8 mag. Observations started at twilight.  The observations began at zenith distance = 61 deg. The sun  altitude  is -16.8 deg. 

The galactic latitude b = 63 deg., longitude l = 39 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2929205

We obtain a following upper limits.  

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

   11047 | 2025-07-08 17:08:56 |         MASTER-SAAO | (14h 49m 32.05s , +26d 51m 11.1s) |   C |    60 | 18.1 |        
   11047 | 2025-07-08 17:08:56 |         MASTER-SAAO | (14h 51m 28.75s , +26d 35m 32.5s) |   C |    60 | 18.0 |        
   11275 | 2025-07-08 17:12:44 |         MASTER-SAAO | (14h 51m 31.65s , +26d 35m 43.8s) |   C |    60 | 17.9 |        
   11335 | 2025-07-08 17:12:44 |         MASTER-SAAO | (14h 51m 31.65s , +26d 35m 43.8s) |   C |   180 | 18.7 |  Coadd 
   11275 | 2025-07-08 17:12:44 |         MASTER-SAAO | (14h 49m 32.60s , +26d 51m 19.6s) |   C |    60 | 18.0 |        
   11335 | 2025-07-08 17:12:44 |         MASTER-SAAO | (14h 49m 32.59s , +26d 51m 19.6s) |   C |   180 | 18.8 |  Coadd 
   11369 | 2025-07-08 17:14:18 |         MASTER-SAAO | (14h 51m 34.49s , +26d 37m 22.8s) |   C |    60 | 18.0 |        
   11369 | 2025-07-08 17:14:18 |         MASTER-SAAO | (14h 49m 35.36s , +26d 52m 58.0s) |   C |    60 | 18.1 |        
   11462 | 2025-07-08 17:15:51 |         MASTER-SAAO | (14h 51m 29.28s , +26d 36m 44.1s) |   C |    60 | 18.0 |        
   11462 | 2025-07-08 17:15:51 |         MASTER-SAAO | (14h 49m 30.14s , +26d 52m 18.7s) |   C |    60 | 18.0 |        
   11584 | 2025-07-08 17:17:23 |         MASTER-SAAO | (14h 49m 30.78s , +26d 53m 23.3s) |   C |   120 | 18.4 |        
   11584 | 2025-07-08 17:17:23 |         MASTER-SAAO | (14h 51m 29.90s , +26d 37m 48.8s) |   C |   120 | 18.3 |        
   11737 | 2025-07-08 17:19:56 |         MASTER-SAAO | (14h 49m 37.53s , +26d 52m 27.5s) |   C |   120 | 18.4 |        
   11737 | 2025-07-08 17:19:56 |         MASTER-SAAO | (14h 51m 36.64s , +26d 36m 53.2s) |   C |   120 | 18.3 |        
Filter C is a clear (unfiltred) band. 


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