Combined image illustrating the relative brightness between the compact and extended emission at 154 MHz. This image was made by combining (using the task feather in CASA) the RS image (Fig. 3b) with a thresholded version of the INT image, Fig. 2b, only including emission brighter than 4σ. The threshold was needed to remove the relatively strong noise in the INT image which would otherwise distort the weaker parts of the extended emission. Since the brightness difference between compact and extended emission is large, a square-root colour scale is used to better show the large scale emission. The colour scale is in mJy/beam, where the beam is the INT beam in Fig. 2b, i.e., 0.36′′ × 0.23′′. Positions are given relative to the M82 position in Table 1.