Spectral features corresponding to the moving radio burst labelled as Source 2 in Fig. 1. Figures corresponding to Sources 1, 2, and 3 are included in Appendix A. (a) Zoomed-in view of the ORFEES dynamic spectrum showing a 30-s period starting at 13:01:45 UT. The first arrow points at one of the Source 2 bursts shown in the middle–left panel of Fig. 1. (b–c) Time series of the NRH flux density of Source 2 in sfu and ORFEES normalised intensity in arbitrary units at (b) 150 and (c) 173 MHz.