Rotation of the Earth from AD 1663–1972 and the Constancy of G

TIMINGS of 40,000 lunar occultations of stars from 1943–1972 have recently been analysed to determine improvements to the Moon's orbital elements, and difference between the ephemeris (ET), universal (UT) and atomic (IAT) time scales. Full details are to be published elsewhere, but the analysis for the period for which the atomic time scale is available are of immediate interest. They can be used in conjunction with results of earlier analyses to give a clearer picture of variations of the rate of rotation of the Earth and to provide evidence that is relevant to whether the constant of gravitation, G, is variable.