Tycho Brahe (1546–1601)
Took lots of precise stellar measurements in a purpose-built observatory – by eye, before telescopes were invented!
Tycho wanted to combine what he saw as the geometrical benefits of Copernican heliocentrism with the philosophical benefits of the old Ptolemaic system into his own model of the universe.
His precise measurements indicated that "new stars" (stellae novae, now called supernovae), in particular that of 1572 (SN 1572), lacked the parallax expected in sublunar phenomena and were therefore not tail-less comets in the atmosphere, as previously believed, but were above the atmosphere and beyond the Moon. Using similar measurements, he showed that comets were also not atmospheric phenomena, as previously thought, and must pass through the supposedly immutable celestial spheres.