Ephemeris
An ephemeris (Greek ephēmeros, of one day) is a daily table of the positions of the Sun, Moon and planets in the zodiac. Essential tool of astrology and astronomy. Modern ephemerides are calculated by computer; classical ones (Raphael's Ephemeris, since 1819) were tabulated by hand.
Use in astrology
Without ephemeris, no natal chart calculation. Modern software automatically uses ephemerides from NASA/JPL or Swiss Ephemeris (precision until 13201 BC).