  Relativistic viscous hydrodynamic fits to RHIC data on the centrality
dependence of multiplicity, transverse and elliptic flow for sqrt{s}=200 GeV
Au+Au collisions are presented. For Glauber-type initial conditions, while data
on integrated v_2 is consistent with a ratio of viscosity over entropy density
up to eta/s=0.16, data on minimum bias v_2 seems to favor a much smaller
viscosity over entropy ratio, below the bound from the AdS/CFT conjecture. Some
caveats on this result are discussed.
