Time-varying component of the difference between TCG and TCM. δ L _Gm is obtained by computing the residuals for Equation (30) using DE440 and the Keplerian model. The accumulated error in rate estimation throughout a lunar orbit can be as high as ∼75 ns. When the fluctuating components are modeled and accounted for, the clocks on the Moon can be synchronized to within a few nanoseconds a day with daily steers of the order of 1 ns. For comparison, the timescale at the National Institute of Standards and Technology (NIST) is routinely steered, and it can be as high as 250 ps day⁻¹. As a result, the Coordinated Universal Time (UTC) realized locally at Boulder, CO, UTC(NIST), stays within ±2 ns with respect to UTC over 1 yr.