Hipparchus was best know for what discovery?

Hipparchus is best known for his development of trigonometry and his introduction of a systematic way to measure the positions of celestial bodies. He created the first known star catalog, which included the brightness and positions of over 850 stars. Additionally, he is credited with the discovery of the precession of the equinoxes, demonstrating that the orientation of the Earth's axis shifts over time. His work laid the foundations for future astronomical studies.