Ground level enhancement GLE #77 on 11 November 2025: a data summary

A very strong solar energetic particle event took place on 11-Nov-2025. It was registered by the worldwide network of neutron monitors as a ground-level enhancement (GLE) #77, which appeared to be one of the strongest registered GLEs. The peak and integral intensities of GLE #77 reached about 125 (165) % and 600 (800) %hr, respectively, for standard (bare) neutron monitors. It had a complicated, multi-component anisotropic structure caused by the complexity of the solar coronal and heliospheric conditions. In this work, verified datasets related to this event are provided along with general analyses. The solar and heliospheric conditions are overviewed, including the analysis of solar radio-emission and the location of the primary particle acceleration. Measurements of solar energetic particles in space, near the first Sun-Earth Lagrange point (L1) onboard the SOHO spacecraft, and in geostationary orbit onboard the GOES-19 spacecraft, are presented, revealing a long-duration, hard-spectrum intense solar particle event. The analysed event produced radiation hazards at high-latitude flight-altitude regions and triggered multiple GLE alarms in the monitoring systems. This work presents a solid, verified basis for a comprehensive, detailed analysis of GLE #77 produced by a strong eruptive event on the Sun.A very strong solar energetic particle event took place on 11-Nov-2025. It was registered by the worldwide network of neutron monitors as a ground-level enhancement (GLE) #77, which appeared to be one of the strongest registered GLEs. The peak and integral intensities of GLE #77 reached about 125 (165) % and 600 (800) %hr, respectively, for standard (bare) neutron monitors. It had a complicated, multi-component anisotropic structure caused by the complexity of the solar coronal and heliospheric conditions. In this work, verified datasets related to this event are provided along with general analyses. The solar and heliospheric conditions are overviewed, including the analysis of solar radio-emission and the location of the primary particle acceleration. Measurements of solar energetic particles in space, near the first Sun-Earth Lagrange point (L1) onboard the SOHO spacecraft, and in geostationary orbit onboard the GOES-19 spacecraft, are presented, revealing a long-duration, hard-spectrum intense solar particle event. The analysed event produced radiation hazards at high-latitude flight-altitude regions and triggered multiple GLE alarms in the monitoring systems. This work presents a solid, verified basis for a comprehensive, detailed analysis of GLE #77 produced by a strong eruptive event on the Sun.