There are also variants, for some science cases it is preferrable to get out of the Earth referential and move to e.g the barycentric reference frame and use th

There are also variants, for some science cases it is preferrable to get out of the Earth referential and move to e.g the barycentric reference frame and use the Barycentric Julian Date [1], which can itself be expressed in different standards (UTC, TAI (atomic time), TDB etc ...) [1] https://en.wikipedia.org/wiki/Barycentric_Julian_Date https://en.wikipedia.org/wiki/Barycentric_Julian_Date