rate through the inner boundary ($R_{\rm in}$) of the disk is presented in figure 3. Note that since the mass flow rate depends sensitively on $R_1$ as $\dot M\propto R_{\rm in}^{2.6}$ and since $R_{\rm in}$ is much larger than that of the marginally stable circular orbit ($3r_{\rm g}$) in our calculations, due to the crude zoning, our quiescent mass-flow rate is much larger than that given by the fine-mesh calculations of Ludwig et al. (1994). However, the qualitative behavior should be adequately captured by these models.

The indirect irradiation leads to a lower ${\dot M}_{\rm in}$ in quiescence due to a higher depletion of the disk mass during outburst. The mass-transfer rate through the inner edge of the disk determines one component of the soft X-ray flux. In the current models, ${\dot M}_{\rm in}$ does not begin to rise until 13.6 d before the primary optical peak, over two weeks since the start of the optical display. The peak in the mass flow rate occurs about 20 d after the primary optical maximum and about 30 d after the first rise in the inner mass-flow rate. Qualitatively, these models predict that the optical flux from the outer disk should rise 