  We investigate conditions on a graph $C^*$-algebra for the existence of a
faithful semifinite trace. Using such a trace and the natural gauge action of
the circle on the graph algebra, we construct a smooth $(1,\infty)$-summable
semfinite spectral triple. The local index theorem allows us to compute the
pairing with $K$-theory. This produces invariants in the $K$-theory of the
fixed point algebra, and these are invariants for a finer structure than the
isomorphism class of $C^*(E)$.
