Milagro is a ground-based TeV gamma-ray telescope in the Jemez mountains near Los Alamos NM. Designed to image TeV gamma-ray sources, it is also sensitive to energetic solar particles above the local geomagnetic cutoff. It sits relatively close to the Climax neutron monitor in Colorado. Because of their geomagnetic proximity, these two instruments can be jointly used to construct a time-dependent spectrum for GLE events unaffected by particle anisotropies. Modeling of the performance of both instruments to both isotropic and anisotropic particle distributions is underway and will be used to constrain the 2005 January 20 spectrum during the brief event onset as well as the abrupt decay. The multiple data channels in the Milagro instrument are also sensitive to large anisotropies. We present ongoing results of the spectrum and anisotropy of the 2005 January 20 GLE.

Milagro

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 1 (SH), pages 285-288