planetary tables and star catalog published in 1627 by Johannes Kepler (Kepler, Johannes), based principally on the observations of Tycho Brahe. The best of the pretelescopic catalogs, it is accurate to a few minutes of arc and contains positions for 1,005 stars (increased by Kepler from Tycho's 777) and tables and directions for locating the planets. It is the first catalog to include corrective factors for atmospheric refraction, and logarithmic tables. It was named for Rudolf II, Holy Roman emperor and patron of Kepler and Tycho.