Overplot of the lines detected towards Cas A (Figs. 9i, 9ii) and Cyg A (Fig. 9iii) for LOFAR LBA (black) and NenuFAR (red). The panels in Fig. 9i compare the detections of LOFAR LBA in the frequency range ~35 to ~68 MHz, from Oonk et al. (2017). The panels in Fig. 9ii compare the detection of LOFAR LBA from ~10 to ~35 MHz, from Salas et al. (2017). The panels in Fig. 9iii compare the detection of LOFAR LBA from ~35 to ~57 MHz, from Oonk et al. (2014). The top panel (LOW) presents the detections of LOFAR LBA in the frequency range ~33 to ~43 MHz, the middle panel (MID) presents the detection from ~39 to ~49 MHz and the bottom panel (HIGH) is the detections from ~44 to ~57 MHz. The detections from NenuFAR were rebinned to the same velocity resolution as LOFAR, and the same transitions were included in the stacks.