[7373737373]

Is there an explanation somewhere of how JPL knows/receives the latest satellite position data?

I think I've read about maneuvers being sent in advance, but once a maneuver (or flyby) actually happens (which may result in deviations from the plan), how (fast) does the ephemeris data actually align with reality through measurement of the actual spacecraft position and speeds again?

[dard]

Sorry, I know some of the ways measurements are taken for satellite orbits, but not who actually does them or how that information makes its way to JPL.