VDA based on onset times of Solar Orbiter EPT and HET electron channels. The horizontal axis shows the inverse of the average unit-less speed of electrons, as observed in each channel. The vertical axis presents the determined onset time for each energy channel. Onset times observed by EPT (HET) are marked in green (blue). The horizontal error bars represent the width of the energy channels, and the vertical error bars represent the time resolution used to determine the onsets (1 second). The orange line represents the linear fit to the first 16 energy channels of EPT and the first channel of HET, respectively. The onset times that are not considered in the fit have a white middle on the data points.