Times of solar/lunar eclipses, planetary ingresses (moving into a new sign), and retrograde motion.
Modern GNSS signals transmit "broadcast ephemeris" data. This contains precise orbital parameters that your phone or car's GPS receiver uses to calculate the satellite’s exact position, allowing it to determine your location on Earth. Ephemeris
Astrologers use these tables to track planetary "transits" (the movement of planets through zodiac signs) and generate birth charts. Scientific and Technical Data Times of solar/lunar eclipses