General information
IceCube-260722A is an IceCube Bronze track-like high-energy neutrino candidate detected on 2026-07-22 at 06:58:22.82 UT, with refined position RA 190.55 deg and Dec 31.0 deg. Multiple follow-up reports were issued, but the main optical candidate was later classified as an unrelated Type Ia supernova.
Wavelength coverage
- Neutrino: IceCube detected the alert event and later found zero additional track-like events in both a 1000 s window and a 2 day window, with p-value 1.00 in both searches.
- Gamma-ray: IceCube reported no known gamma-ray sources from the Fermi LAT 16-year Source List within the 90% uncertainty region.
- Optical: MASTER-SAAO observed the field in clear band with an upper limit of 17.6 mag; ZTF observed in g and r bands and found ZTF26abjbxfs / AT 2026vts; ATLAS forced photometry showed marginal o-band detections; NOT/ALFOSC obtained spectroscopy of the candidate.
No observations are mentioned in X-ray, radio, infrared, ultraviolet, or gravitational waves.
Lightcurve and spectrum
- ZTF26abjbxfs / AT 2026vts was detected by ZTF at r=19.78 +/- 0.07 mag and reported as very blue, with g-r = -0.2.
- Assuming the nearby galaxy redshift, ZTF reported a current absolute magnitude of M=-18.8.
- ATLAS forced photometry showed two marginal 3 sigma o-band detections at m=19.6 +/- 0.2 mag, 3-4 days before the ZTF observations.
- NOT/ALFOSC spectroscopy matched the transient to Type Ia supernova templates, and the circular states it is unrelated to the neutrino.
Redshift
A spectroscopic redshift of z=0.0978 is reported for SDSS J124512.84+303550.1, the galaxy on whose edge ZTF26abjbxfs / AT 2026vts appeared. The ZTF circular assumed this redshift for the transient when estimating M=-18.8, but later spectroscopy classified the transient as an unrelated Type Ia supernova.
What’s special vs typical
The event received notable follow-up and initially had a plausible optical transient candidate within the neutrino localization, but the candidate was spectroscopically shown to be an unrelated Type Ia supernova and IceCube found no additional neutrino excess.