Erratum to: Analysis of velocity-mapped ion images from high-resolution crossed-beam scattering experiments: a tutorial reviewAlexander von Zastrow, Jolijn Onvlee, David H. Parker and Sebastiaan YT van de MeerakkerEPJ Techn Instrum, 2 1 (2015) 16DOI: https://doi.org/10.1140/epjti/s40485-015-0026-6