Constraining general relativity at z ∼ 0.299 MUSE Kinematics of SDP.81

General Relativity has been successfully tested on small scales. However, precise tests on galactic and larger scales have only recently begun. Moreover, the majority of these tests on large scales are based on the measurements of Hubble constant (H₀), which is currently under discussion. Collett et al. (2018) implemented a novel test combining lensing and dynamical mass measurements of a galaxy, which are connected by a γ parameter, and found γ=0.97±0.09, which is consistent with unity, as predicted by GR. We are carrying out this same technique with a second galaxy, SDP.81 at z=0.299, and present here our preliminary results.