oh man, and if you truly want to be objective, you have to once again repudiate geocentrism, and put the relativistic frame's point of origin in the center of the sun
(Checks watch) For any event Ε(σ ,τ) observed at system σ at time τ , it’s after Ε(σ,τ-1) and prior to Ε(σ,τ+1), but only for system σ, and assuming linearized local event causality.
Elapsed where? Because one of the systems that needs to know what time it is is a piece of embedded hardware that's been sitting in a satellite in geosynchronous orbit for the past five years...
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Or: system time.
https://www.nasa.gov/general/nasa-to-develop-lunar-time-standard-for-exploration-initiatives/