Some New Observing Features of a Solar Radio Spectral Eventon August 25,1999

A broadband solar radio type III burst was observed on August 25,1999 at Purple Mountain Observatory with waveband of 4.5-7.5 GHz. It was also observed at Beijing Astronomical Observatory with waveband of 5.2-7.6 GHz. Therefore, it is the first common spectral event observed in China. The type III bursts are gathered into more than 10 groups and drift in opposite directions, but the reverse drifting prevails. The largest bandwidth of type III burst reaches ≥3 GHz and may be the broadest bandwidth of the reverse type III burst ever observed up to the present. Some new observing characteristics of fine structures are found, for example, fiber-like, V-shaped and neck-ring-like structures. Especially, the neck-ring-like structure is probably first discovered in cm waveband and may be the evidence of twisted rope of magnetic lines.