Flux densities and spectral indices of the moving radio sources 1 (panel a), 2 (panel b), and 3 (panel c). The flux densities of the moving radio sources are estimated for both Stokes I (solid lines) and Stokes V (dashed lines) emission in each panel. The spectral indices were estimated by fitting a power-law function to the lower NRH frequencies, where the radio sources are clearly observed in images: 150–228 MHz, 150–173 MHz, and 150–173 MHz, for Sources 1, 2, and 3, respectively.