The Dutch Navigators
Ian Ridpath attributes twelve constellations of the southern celestial hemisphere to the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman.
The Expedition to the East Indies
Petrus Plancius (1552 - 1622) was a Dutch astronomer, cartographer, and theologian. On the occasion of the first Dutch expedition to the East Indies, in 1595, Plancius asked Keyser, the chief pilot on the Hollandia, to make observations to fill in the blank area around the south celestial pole on European maps of the south celestial hemisphere.
Plancius Records the Constellations
Keyser died in Java the following year, but his catalog of 135 stars was delivered to Plancius, who inscribed the twelve new constellations on a globe he prepared in 1598. These constellations were then incorporated by Johannes Bayer in his sky atlas, the Uranometria, published in 1603.
De Houtman's Contribution
Frederick de Houtman assisted Keyser on his observations during the first expedition to the East Indies. During later expeditions he added further stars to the list of those observed by Keyser. De Houtman and Keyser now share credit for the invention of the new southern constellations.
Twelve New Constellations
The twelve constellations invented by Keyser and de Houtman are:
Plancius Adds Three More
Petrus Plancius himself invented a number of new constellations. Most of those added by Plancius were not generally accepted. Of Plancius new constellations only the following three are still accepted: