RHESSI observation of the M4.0 flare on 17 March 2002 Original Research Article

The M4.0/SF flare on 17 March 2002 is a good example of the early observations with RHESSI. We presenthard X-ray images, light curves and energy spectra of individual hard X-ray sources, the spatial relationship between the hard X-ray sources and the Hα emission regions, and comparisons of light curves observed by RHESSI and GOES. We found that the picture exhibited by RHESSI is consistent with the general cartoon of a solar flare. In particular, we showed that the hard X-ray image spectra could be explained by a power-law electron beam with a lower energy cutoff Ec. The derived Ec could be as high as 40 keV, larger than the usually value of 20 keV.