The problem of deducing ce from heat pulse propagation measurements is addressed. An extended diffusive model is described, which takes.into account perturbed source and sink terms. ce is expressed as a function of two observables, the heat pulse velocity nHP and the radial damping rate a: ce 4.3 a nHP/a. This expression is checked against full transport e simulations and found accurate. Finally it is shown that the thus inferred ce is a local value, not influenced by the ce-profile outside the measuring region.