LAUSR

${\mathrm{SrAuSi}}_{3}$ is a noncentrosymmetric superconductor (NCS) with ${T}_{c}=1.54$ K, which to date has been studied only via macroscopic techniques. By combining nuclear-magnetic-resonance and muon-spin-rotation measurements, we investigate both the normal and the superconducting phase of ${\mathrm{SrAuSi}}_{3}$ at a local level. In the normal phase, our data indicate a standard metallic behavior with weak electron correlations and a Korringa constant ${S}_{\mathrm{exp}}=1.31\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ sK. The latter, twice the theoretical value, can be justified by the Moriya theory of exchange enhancement. In the superconducting phase, the material exhibits conventional BCS-type superconductivity with a weak-coupling $s$-wave pairing, a gap value $\mathrm{\ensuremath{\Delta}}(0)=0.213(2)$ meV, and a magnetic penetration depth $\ensuremath{\lambda}(0)=398(2)$ nm. The experimental proof of weak correlations in ${\mathrm{SrAuSi}}_{3}$ implies that correlation effects can be decoupled from those of antisymmetric spin-orbit coupling, thus enabling accurate band-structure calculations in the weakly correlated NCSs.