it doubtful that we observe such a phenomenon.

Assuming the He[ii]{} emission arises from the heated hemisphere of the secondary, the semi-amplitude $900$ km s$^{-1}$ [ (underestimating the real $K_2$)]{} gives a rough constraint on the mass function through : $$f(M)=\frac{M_1^3\sin^3 i}{(M_1+M_2)^2}=\frac{K_2^3 P_{\rm orb}}{2 \pi G}
\label{eq:fm}$$ This gives a [*minimum*]{} mass for the primary of 12 M$_\odot$, which [ would make XTE J1118+480 at least as massive as the black hole in V404 Cyg. Lower inclinations would imply an even greater mass making this system rather unusual compared to the dynamical masses inferred in other SXTs (see, e.g., van Paradijs & McClintock 1995). Although we cannot formally reject this possibility, the He[ii]{} emission is unlikely to originate from the heated surface of the secondary.]{}

The He[ii]{} emission is more likely to originate from the stream-disk interaction. [ Typically, the hotspot is located (see above references) somewhere between the ballistic gas stream trajectory and its corresponding Keplerian velocity (which defines a circularization radius)]{}. We derive a [ lower limit on $K_2(q)$ (hence a lower limit on the primary mass)]{} by assuming that the emission is located at the intersection of the two trajectories. The values of $K_2$ and $q$ for 