Doesn't astronomy already use their own time reference standard? It seems like JPL (NASA) and the scientific community have defined two currently used sets of

Doesn't astronomy already use their own time reference standard? It seems like JPL (NASA) and the scientific community have defined two currently used sets of time standards for observations from Earth and from space near Earth. https://en.wikipedia.org/wiki/Time_standard#Time_standards_for_planetary_motion_calculations https://en.wikipedia.org/wiki/Time_standard#Time_standards_f... Barycentric Coordinate Time (TCB) and Geocentric Coordinate Time (TCG) with DE430 as the current revision of their standard https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory_Development_Ephemeris https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory_Deve...