Forward- and reverse-drift herringbones showing opposite senses of circular polarisation. (a) ORFEES dynamic spectrum showing herringbones drifting to both high (forward drift) and low frequencies (reverse drift) on either side of a bright backbone. (b) AIA 211 Å image of the Sun showing the onset of the CME and overlaid with Stokes I contours of radio sources at 173 and 228 MHz corresponding to the forward- and reverse-drift herringbones, respectively. (c) AIA 211 Å image of the Sun showing the onset of the CME and overlaid with Stokes V filled contours of radio sources at 173 and 228 MHz corresponding to the forward- and reverse-drift herringbones, respectively. The colour bars show the brightness temperature of the Stokes V contours.