Tycho Brahe · 1925
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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.
Six years of observation, 1590 to 1595. Each year is set out as the logbooks kept it: observations of the Sun and Moon, of Saturn, Jupiter, Mars, Venus and Mercury, and of the fixed stars in the zodiac and in the northern and southern constellations.
The published books of Tycho Brahe give his conclusions. The logbooks give the evidence: the data from which Kepler derived the elliptical orbit of Mars, and still the most accurate body of naked-eye positional astronomy ever assembled. The manuscripts themselves have never been digitized, so Dreyer’s edition is one of only two complete and reliable witnesses to them.
The source is volume XII of Dreyer’s Tychonis Brahe Dani Opera Omnia (Copenhagen, 1925). The volumes before it are Thesaurus Observationum, Tomus Primus and Tomus Secundus; the record continues in Tomus Quartus.