Tycho Brahe provided the precise astronomical data that Johannes Kepler used to derive his laws of planetary motion. Brahe’s observations, especially of Mars, were far more accurate than most earlier naked-eye measurements.
Brahe built and used large precision instruments before the telescope became an astronomical tool. From his observatory on the island of Hven, he recorded planetary positions over many years. Although he rejected a fully heliocentric system, his data later became essential to the model he had opposed.
Kepler inherited or gained access to Brahe’s observations after Brahe’s death in 1601. Kepler initially tried to fit Mars’s motion with circular orbits, following the long tradition of perfect circles. The measurements did not fit closely enough, so he eventually concluded that Mars follows an ellipse. That breakthrough became his First Law; his Second Law described changing orbital speed, and his Third Law connected orbital periods with distance from the Sun.
The important distinction is between observation and explanation: Brahe supplied the measurements, while Kepler turned them into mathematical laws. Newton later provided the physical theory of gravity that explained why Kepler’s laws work.