Reprocessing of hard X-ray emission in X-ray novae

Much of the visual and ultraviolet luminosity in X-ray novae is likely to result from reprocessing of X-rays illuminating an accretion disk. During the initial stages of its 1992 outburst, GRO J0422+32 exhibited short-time-scale flickering intense enough to be seen in the individual BATSE LAD detectors with a nominal 1-second time resolution. We obtained photometry with continuous minute sampling during this period, in which short-time-scale flickering as well as hourly trends are evident. In addition, we obtained resolution spectroscopy sampled at 10-minute intervals over a baselines comparable to a binary orbital period. We present results of cross-correlation analysis between the optical and hard X-ray of time-series data sets. No statistically significant time lags can be established. For the more recent X-ray nova GRO 1655 40, we have spectra obtained on separate nights within one weeks time, bracketing an upturn in the BATSE light curve, which exhibited dramatic evolution.