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From Johann Bayer's "Uranometria" (1603), the first 'true' star-atlas. This and other copper-engraved images from the book demonstrate a notable feature of this atlas: the sheer beauty of the plates. Alexander Mair, the artist clearly found some inspiration in the De Gheyn engravings in the Aratea published by Hugo Grotius in 1600, but most of Bayer's constellation figures have no known prototype. Significantly, each plate has a carefully engraved grid, so that star positions can be read off to fractions of a degree. These positions were taken, not from Ptolemy's catalog, but from the catalog of Tycho Brahe, which had circulated in manuscript in the 1590s, yet not printed until 1602. Another important feature of the atlas was the introduction of a new system of stellar nomenclature, Bayer assigning Greek letters to the brighter stars, generally in the order of magnitude. 1603