Fine example of Johann Bayer's map of the constellation Triangle.
Triangulum Australe appears in the sky of the Southern Hemisphere. The Southern Triangle is one of the twelve star groups that were formed into new constellations by Johann Bayer in his Uranometria. Bayer had obtained a description of the sky from the Dutch navigator, Pieter Keyser (Petrus Theodori). This enabled him to fill in parts of the southern sphere unknown to the ancient astronomers. The other constellations of Bayer were Apis, the Bee (now Musca, the Fly), Avis Indica, the Bird of Paradise (now Apus), Chamaeleon, the Chameleon, Dorado, the Swordfish, Grus, the Crane, Hydrus, the Water Snake-not to be confused with Hydra, the Water Serpent-Indus, the American Indian, Phoenix, Piscis Volans, the Flying Fish, (now simply Volans), and Tucana, the Toucan.
Perhaps the most important of all celestial atlases is Bayer's Uranometria, the forerunner of all star atlases which contained 51 star charts, of which 48 were Ptolomeic constellations. Each plate has a carefully engraved grid, so that star positions can be read off to fractions of a degree. These positions were taken,from the catalog of Tycho Brahe, which had circulated in manuscript in the 1590s, but which was only printed in 1602.
Another important feature of the atlas was the introduction of a new system of stellar nomenclature. Bayer assigned Greek letters to the brighter stars, generally in the order of magnitude, so that the bright star in the Bull's eye became alpha Tauri (and the brightest star in the Centaur became our familiar alpha Centauri.) These letters were placed on the charts themselves, and also in a table that accompanied each chart. Bayer's charts are rarely offered seperately on the market.