MESSENGER solar energetic electron peak intensities versus CA. The vertical dashed lines indicate the connection angles CA = −65° (left) and CA = +33° (right). The horizontal lines show the truncation level of the sample. (a) Includes all SEE events selected for the study. The colour of the points depends on the CA. The purple square points correspond to the sample of well-connected events, namely −65° ≤ CA ≤ +33°. The rest of the sample is indicated with green circles. (b) Only events accompanied by a CME-driven shock are shown, and these are colour-coded according to the shock speed at the apex.