Horizons! https://ssd.jpl.nasa.gov/horizons/ https://ssd.jpl.nasa.gov/horizons/ IIRC, the Telnet interface is technically more fully-featured than the others,

Horizons! https://ssd.jpl.nasa.gov/horizons/ https://ssd.jpl.nasa.gov/horizons/ IIRC, the Telnet interface is technically more fully-featured than the others, although that's probably simply because it would have come into existence first.