which the intersection matches the He[ii]{} emission are plotted as a dashed line in the left panel of Fig. \[fig:cons1\].

A comparison between the two estimates of $K_2(q)$ shows that values of $0.02\lsim q\lsim 0.1$ best fit the data in the sense that they minimize the discrepancies. Formal agreement requires $q\approx0.045$ ($K_2\approx430$ km s$^{-1}$) but this is, of course, model-dependent. Knowing $q$ and $K_2$, the mass function (Eq. \[eq:fm\]) gives the inclination $i$ as a function of $M_1$. This relation is plotted in Fig. \[fig:cons1\] (right panel) for the two extreme cases ($q=0.02$,$K_2=500$ km s$^{-1}$) and ($q=0.1$,$K_2=350$ km s$^{-1}$). Clearly, a NS would require large inclinations while a BH gives intermediate inclinations. [ Given the assumptions made for the interpretation of the peak-to-peak velocity and the He[ii]{} emission, we are likely to underestimate $K_2$ in both cases. This would only strengthen the case for a black hole primary.]{}

The stream-disk interaction apparently extends some way along the Keplerian velocity trace as previously seen in other SXTs (e.g. Harlaftis et al. 1996). This could also be a numerical artifact [ possibly due to an inaccurate orbital period]{}. The second weaker emission region in the H$\alpha$ velocity map could be due to 