Abstract

The main aim of the paper is to estimate, from multispectral observations, the plasma parameters in a microwave burst source which was also the site of spike emission. This information is essential for the determination of the spike emission process. By analyzing one dimensional source distributions observed with the SSRT at 5.7 GHz and correlating them with YOHKOH X-ray and Nobeyama 17~GHz images, we concluded that the microwave emitting region was larger than the soft X-ray loop-top source, and that the origin of the burst could be explained by gyrosynchrotron emission of non-thermal electrons in the magnetic field of approximately 100~G. It was shown that the source of 5.7~GHz spikes observed during the burst was located close to an SXR-emitting loop with high density and temperature and a relatively low magnetic field. Thus, plasma emission is the most favourable radiation mechanism for the generation of the subsecond microwave pulses.