  Let $X$ be a real algebraic convex 3-manifold whose real part is equipped
with a $Pin^-$ structure. We show that every irreducible real rational curve
with non-empty real part has a canonical spinor state belonging to $\{\pm 1\}$.
The main result is then that the algebraic count of the number of real
irreducible rational curves in a given numerical equivalence class passing
through the appropriate number of points does not depend on the choice of the
real configuration of points, provided that these curves are counted with
respect to their spinor states. These invariants provide lower bounds for the
total number of such real rational curves independantly of the choice of the
real configuration of points.
