  We present observations of the 2002 September 30 white-light flare, in which
the optical continuum emission near the Halpha line is enhanced by ~10%. The
continuum emission exhibits a close temporal and spatial coincidence with the
hard X-ray (HXR) footpoint observed by RHESSI. We find a systematic motion of
the flare footpoint seen in the continuum emission; the motion history follows
roughly that of the HXR source. This gives strong evidence the this white-light
flare is powered by heating of nonthermal electrons. We note that the HXR
spectrum in 10-50 keV is quite soft with gamma being ~7 and there is no HXR
emission above 50 keV. The magnetic configuration of the flaring region implies
magnetic reconnection taking place at a relatively low altitude during the
flare. Despite a very soft spectrum of the electron beam, its energy content is
still sufficient to produce the heating in the lower atmosphere where the
continuum emission originates. This white-light flare highlights the importance
of radiative backwarming to transport the energy below when direct heating by
beam electrons is obviously impossible.
