From sl(2) Kirby weight systems to the asymptotic 3-manifold invariant

We give a construction of Kirby weight systems associated to sl(2) and valued into the finite field Z/pZ. We show that it is possible to apply this sequence of weight systems on the universal invariant of framed link. We also show that the corresponding sequence admits a Fermat limit, which defines an asymptotic rational homology 3-sphere quantum invariant. Moreover, this asymptotic invariant coincides with the Ohtsuki invariant.