(a) Dynamic spectrum of solar radio emission with a drift-pair burst recorded with LOFAR on 2017 July 12 (Sun-integrated, in relative units). (b) Time profile of the radio flux at a single frequency (32 MHz). (c) Corresponding time profile of the visible radio source position (distance from the solar disk center). (d) Corresponding time profile of the visible radio source area (at half-maximum level). Red lines represent linear fits to the time profiles of the source parameters in the intervals shown. The error bars represent one standard deviation.