Images of M82 at 118 MHz (upper panel) and 154 MHz (lower panel) made using international LOFAR baselines (longer than 60 kλ). The CLEAN restoring beam is shown in the lower left corner of each figure, 0.45′′ × 0.29′′ at 118 MHz and 0.36′′ × 0.23′′ at 154 MHz. The rms noise levels are 0.30 mJy/beam at 118 MHz and 0.15 mJy/beam at 154 MHz. For deconvolution parameters, see Sect. 3.1. Measured brightness values are listed in Table 2.