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The velocity dispersion of the ultra diffuse galaxy NGC1052-DF2 was found tobe $\sigma_{\rm gc}=7.8^{+5.2}_{-2.2} \ \mathrm{kms^{-1}}$, much lower thanexpected from the stellar mass -- halo mass relation and nearly identical tothe expected value from the stellar mass alone. This result was based on theradial velocities of ten luminous globular clusters that were assumed to beassociated with the galaxy. A more precise measurement is possible from highresolution spectroscopy of the diffuse stellar light. Here we present anintegrated spectrum of the diffuse light of NGC1052-DF2 obtained with the KeckCosmic Web Imager, with an instrumental resolution of $\sigma_{\rminstr}\approx 12 \ \mathrm{kms^{-1}}$. The systemic velocity of the galaxy is$v_{\rm sys}=1805\pm 1.1 \ \mathrm{kms^{-1}}$, in very good agreement with theaverage velocity of the globular clusters ($\langle v_{\rm gc}\rangle = 1803\pm2 \ \mathrm{kms^{-1}}$). There is no evidence for rotation within the KCWIfield of view. We find a stellar velocity dispersion of $\sigma_{\rm stars}=8.4\pm 2.1 \ \mathrm{kms^{-1}}$, consistent with the dispersion that was derivedfrom the globular clusters. The implied dynamical mass within the half-lightradius $r_{1/2}=2.7 \ \mathrm{kpc}$ is $M_{\rm dyn}= (1.3 \pm 0.8) \times 10^8$ M$_{\odot}$, similar to the stellar mass within that radius ($M_{\rmstars}=(1.0 \pm 0.2) \times 10^8 \ \mathrm{M}_{\odot}$). With this confirmationof the low velocity dispersion of NGC1052-DF2, the most urgent question iswhether this "missing dark matter problem" is unique to this galaxy or appliesmore widely.

Still Missing Dark Matter: KCWI High-Resolution Stellar Kinematics of NGC1052-DF2