of the overlapping parts of these light curves using the methodology described in the next section yields a lag of the optical variations relative to the X-ray of $\tau= 6^{+62}_{-112}$ days with a correlation coefficient $r_{\rm max} = 0.74$, i.e., the mean X-ray and optical fluxes are indeed correlated once the high-frequency variability is suppressed. The lag between variations in the two wavebands is highly uncertain, but consistent with zero or any small time lag expected in the continuum emitting region.

Emission-Line Variability
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Comparison of the optical continuum and emission-line light curves shows that the variations in each are quite similar, indicating that the time delay between them is small. The time delay between continuum and emission-line variations can be quantified by cross-correlation of the light curves. During the first year, there is a period from JD2450183 to JD2450262 in which the light curves are well-sampled and the character of the variations permits an accurate cross-correlation measurement. In Table 3, we refer to this subset of data as “subset 1”, and we plot this part of the light curves in an expanded form in Fig. 2. We cross-correlate the data shown here by using the interpolation cross-correlation function (ICCF) 