First analysis of GLE 72 event on 10 September 2017: Spectral and anisotropy characteristics

Abstract: Using neutron monitor and space-borne data we performed an analysis of the second ground level enhancement of solar cycle 24, namely the event of 10 September 2017 (GLE 72) and derive the spectral and angular characteristics of GLE particles. We employ new neutron monitor yield function and a recently proposed model based on optimization procedure. The method consists of simulation of particle propagation in a model magnetosphere in order to derive the cut-off rigidity and neutron monitor asymptotic directions. Subsequently the rigidity spectrum and anisotropy of GLE particles are obtained in their dynamical evolution during the event on the basis of inverse problem solution. The derived angular distribution and spectra are briefly discussed.