Argo Navis, or the Argo, the ship sailed by Jason and the Argonauts, is an obsolete constellation. One of Ptolemy's original constellations, its very large size was considered unwieldy, and it was broken up into smaller constellations by Nicolas-Louis de Lacaille
in 1752: Carina
, the Keel, Puppis
, the Poop Deck, and Vela
, the Sails. Since this was long after Bayer designated Greek letters for various stars in Argo Navis, each of the three constellations is missing those letters which lie in one of the other constellations.
Lacaille also introduced a fourth constellation, Pyxis
, the Mariner's Compass, which lies in a region formerly occupied by part of Argo Navis' mast. However, none of the Bayer stars from Argo Navis lay in Pyxis, so its Bayer designations are completely separate from those of the other fragments of Argo Navis.
Hevelius' star charts were drawn as they would appear on a celestial globe, which is viewed from the outside of the imaginary celestial sphere. As a result, the east-west (left-right) orientation of the stars is reversed from the view that someone would have looking at the sky from the surface of the Earth (the north-south orientation is not affected by this procedure). So in the illustration above Canis Major is to the left of Argo Navis, but in the sky it would be to the right. Similarly, in the illustration Centaurus is to the right of Argo Navis, but in the sky it would be to the left.