WISPR-I R-map (intensity versus time and Thomson Surface radial distance expressed in R_⊙) during PSP E4. The R-map was calculated from the J-map of Fig. 4 following the procedure outlined in Sect. 3.2. The start and end points of several numbered tracks are marked with pink crosses and the speeds resulting from linear fittings of the associated time-distance pairs are displayed in the right upper part of the plot.