Abstract

A few tens of sub-second pulses (SSP) have been recorded since 1992 by the SSRT (5.7~GHz) and the Nobeyama Radioheliograph (17~GHz). At both frequencies, SSP occurred at any phase of flare bursts. Temporal and spatial characteristics of SSP observed at both frequencies were studied. For three 17~GHz events, BATSE/CGRO data of 64~ms resolution are available. There are several sub-second structures in HXR data which are highly correlated with microwave pulses. Emission mechanisms of SSP are discussed and plasma parameters in the sources are estimated.