This link allows downloading from NASA Horizons server data about the distance of a body (OSIRIS-REX spacecraft ) from the Sun (see link here):
How can I know how the distance is obtained?
- Is it the distance it should have on specified date according to mission schedule?
- Is it measured from Earth by radar?
- Is it an onboard telemetry?
- Is it calculated by the time the light takes to go from Earth to S/C and back?
How can I know whent it was last updated and on which basis?