IceCube-260504A

General information

IceCube-260504A is a track-like high-energy neutrino candidate detected by IceCube on 2026-05-04 21:11:20.90 UTC and distributed via the ICECUBE_Astrotrack_BRONZE alert stream with refined offline localization.

Wavelength coverage

• Neutrinos: IceCube reports the alert and performed follow-up searches for additional track-like events on 1000 s and 2-day timescales, finding none beyond the alert event.
• Gamma-rays (GeV): Fermi-LAT reports no significant new >100 MeV excess within the 90% localization and provides flux upper limits.
• Optical: ZTF observed in g and r bands starting ~55.2 hours after T0 and reports no candidate transients to typical depth ~20.5 mag over 68.2% of the localization. No observations were mentioned in: X-rays, UV, radio, IR, TeV gamma-rays.

Lightcurve and spectrum

• Fermi-LAT: assuming a power-law spectrum with photon index 2.0, >100 MeV 95% flux upper limits are <1.3e-10 ph cm^-2 s^-1 (2008-08-04 to T0), <4.6e-09 ph cm^-2 s^-1 (1 month pre-T0), and <4.7e-08 ph cm^-2 s^-1 (1 day pre-T0); no significant (>5σ) new excess is reported.
• ZTF: 30 s g/r imaging to typical depth ~20.5 mag; no candidate counterparts detected.

Redshift

What’s special vs typical