Analysis of the 1980 November 18 limb flare observed by the hard X-ray imaging spectrometer (HXIS)

Abstract

X-ray images of the 18 November 1980 limb flare taken by the HXIS instrument aboard SMM were analysed. The hard X-rays originated from three spots on the SW limb of the solar disk with different altitudes and time evolution. The locations of the brightest spots in hard and soft X-rays are compared with the predictions of flare models. The X-ray spctra from the pixels with highest count rates can be fitted by power laws. The spatial variation of the spectral index is in agreement with the existence of a non-thermal electron component.