Table 2

The value of the merit function obtained for the analysis of several GLEs (main phase of the event) as a function of the number of the used NM stations. Columns 1–2 correspond to the number and date of the GLE, while columns 3–5 correspond to and number of the used stations (in the brackets) for extended NM network, actual NM network used for the analysis and the reduced NM network, respectively. N.A. depicts the case when the SEP spectra cannot be unfolded. The details for the analysis of the presented GLEs are given in Mishev et al. (2014), Kocharov et al. (2017), Mishev et al. (2018b), Mishev & Usoskin (2016a) as well as in this work.