Lacaille’s Octans

Lacaille’s Octans was positioned with no real regard to the stars that compose it, except for Eta Octantis on the octant’s pivot, and that star is only 6th magnitude. Lacaille did not regard his constellations as recognizable star patterns but simply areas of sky in which he could commemorate the main instruments of the arts and sciences of his era. This illustration comes from a copy of Lacaille’s original map of the southern stars included in the Atlas Céleste of Jean Fortin. The constellation’s name was Latinized to Octans on the second edition of Lacaille’s chart, published in 1763. (Image © Ian Ridpath.)