Panel a: flux density spectrum of NRH data below 445 MHz and RSTN data above 615 MHz, at three separate times between 11:01:40 UT to 11:03:10 UT (times indicated in bottom panel). The flux densities are high at 150 and 173 MHz, fall to a minimum at ~300 MHz, reach a peak ~1 GHz and fall again. This is characteristic of a gyrosynchrotron spectrum at frequencies higher than ~300 MHz with plasma emission dominating at lower frequencies. Panel b: parametric fit of a gyrosynchrotron spectrum from 298 MHz to 4.5 GHz at three separate times.