Update: PrecisionDsdecay constant from full lattice QCD using very fine lattices

We update our previous determination of both the decay constant and the mass of the Dₛ meson using the highly improved staggered quark formalism. We include additional results at two finer values of the lattice spacing along with improved determinations of the lattice spacing and improved tuning of the charm and strange quark masses. We obtain m_Dₛ=1.9691(32) GeV, in good agreement with experiment, and f_Dₛ=0.2480(25) GeV. Our result for f_Dₛ is 1.6σ lower than the most recent experimental average determined from the Dₛ leptonic decay rate and using Vcs from Cabibbo-Kobayashi-Maskawa unitarity. Combining our f_Dₛ with the experimental rate we obtain a direct determination of Vcs=1.010(22), or alternatively 0.9900+0.013-0.016 using a probability distribution for statistical errors for this quantity which vanishes above 1. We also include an accurate prediction of the decay constant of the ηc, f_ηc=0.3947(24) GeV, as a calibration point for other lattice calculations.