Tycho Brahe · 1924
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For twenty-one years on the island of Hven, and afterwards in Bohemia, Tycho Brahe and his assistants recorded what they saw. This volume continues the Thesaurus Observationum, the record gathered from the surviving logbooks by J. L. E. Dreyer for his edition of Tycho’s complete works.
Four years of observation, 1586 to 1589. These were the years when Uraniborg and its underground companion observatory, Stjerneborg, were fully equipped and in continuous use. Each year is set out as the logbooks kept it: positions of the Sun, Moon and planets, and measurements of the fixed stars. An appendix to the observations of 1589 includes a catalogue of the stars in the zodiac.
The published books of Tycho Brahe give his conclusions. The logbooks give the evidence. These are the years of the observatory at its most productive, and the observational record from which Kepler, working from Tycho’s data, derived the laws of planetary motion.
The source is volume XI of Dreyer’s Tychonis Brahe Dani Opera Omnia (Copenhagen, 1924), edited with J. Raeder. The volume before it, covering 1563 to 1585 and opening with Dreyer’s introduction to the whole series, is Thesaurus Observationum, Tomus Primus.