A Fifth-Coordinate Timing Beacon: Clock Synchronisation Across a Transit Link and Its Error Budget

This paper presents a complete design study of the device is a timing beacon pair, one at each end of an Earth-Moon baseline, exchanging pulses through a fifth-coordinate transit path and disciplining two atomic clocks to a common epoch, derived from stated assumptions and computed throughout by the accompanying script. At transit parameter 1.0 the one-way signal time over the Earth-Moon baseline is 1.6836 s. The assembled error budget gives a total root-mean-square timing error of 1021.03 ps, equivalent to a ranging uncertainty of 306.1 mm, dominated by the stated path jitter term. Every figure in the study is a computed result of the stated model and nothing was built or tested: the study is SIMULATED, NOT MEASURED, and its limits are stated as plainly as its performance.