dG/dt measurement and the timing of lunar laser ranging observations

Two fundamental tests of general relativity are achieved using over three decades of lunar laser ranging (LLR) data-confirming the equality of the Sunʹs acceleration rate of the Earth and Moon to about a part in 10^13 precision, and finding no time variation in the strength of Newtonʹs G to precision of a part in 1012 per year. LLR is an ongoing mission, and these tests of physical theory should remain at the frontier of precision for time to come. The contribution of each individual LLR measurement to the precision of Gdetermination varies strongly through the lunar motionʹs monthly cycle and from month to month. A worth function which quantifies this variation is derived and illustrated: it can be employed by observers who have scheduling discretions in order to more rapidly improve the estimation precision for the scientific parameter G.