S.A. Matthews¹, L. van Driel-Gesztelyi², H.S. Hudson³, and N. Nitta⁴

1 Mullard Space Science lab, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT

2 Observatoire de Paris, DASOP, F-92195 Meudon Cedex, France

3 Solar Physics Research Corp./Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagimahara-shi, Kanagawa, 229, Japan.

4 Lockheed Martin Research Laboratory, Palo Alto, CA 94304, U.S.A.

The problem of accounting for the continuum emission that is observed in solar flares is still one which is largely unresolved. These events, called white-light flares (WLFs), place severe constraints on the energy requirements and transport mechanisms operating in the flare. Previous ground-based observations of WLFs have been hampered by various difficulties, including the effects of seeing, although the primary disadvantage has been the difficulty in obtaining coincident observations in white-light, HXR and SXR. The Aspect Camera on the Soft X-ray Telescope (SXT) on Yohkoh has provided a unique database of WLFs with coincident HXR and SXR observations with which to study the relationship between these different emissions and investigate the origins of the white-light emission. We have found that the spatial and temporal coincidence between impulsive white-light and HXR emission is good, but the case for the gradual white-light emission requires further investigation. Using the catalogue of Yohkoh WLFS observed prior to the failure of the Aspect Camera in 1992 (van Driel et al., 1999) we investigate the spatial and temporal relationship between the gradual white-light emission and both the HXR and SXR emission in an attempt to identify its origins.