Abstract
Images of 17 solar flares, corresponding to 61 individual X-ray bursts observed in four energy bands (14-23, 23-33, 33-53, and 53-93 keV) by the Hard X-Ray Telescope (HXT) experiment aboard the Yohkoh satellite have been investigated. The images suggest that the angular size of the hard X-ray sources is of the order of 20 arcsec and that they are of three types: single isolated sources ( ~ 30%), double sources ( ~ 41%), with typical minimum separation of 30-40 arcsec, and multiple sources ( ~ 29%). We have fitted a single power law spectrum to the X-ray emission in the range 20-830 keV, using data from the Hard X-Ray Spectrometer (HXS) experiment. The spectral time evolution of these bursts has been also investigated. Typical spectral index behavior is ``soft-hard-soft''.
