  We show how the measured particle ratios at RHIC can be used to provide
non-trivial information about the critical temperature of the QCD phase
transition. This is obtained by including the effects of highly massive
Hagedorn resonances on statistical models, which are used to describe hadronic
yields. Hagedorn states are relevant close to $T_c$ and have been shown to
decrease $\eta/s$ to the KSS limit and allow for quick chemical equilibrium
times in dynamical calculations of hadrons. The inclusion of Hagedorn states
creates a dependence of the thermal fits on the Hagedorn temperature, $T_H$,
which is assumed to be equal to $T_c$, and leads to an overall improvement of
thermal fits. We find that for Au+Au collisions at RHIC at $\sqrt{s_{NN}}=200$
GeV the best square fit measure, $\chi^2$, occurs at $T_c \sim 176$ MeV and
produces a chemical freeze-out temperature of 170.4 MeV and a baryon chemical
potential of 27.8 MeV.
