THE DRAKON GIGANTIOS was a giant serpent cast at the goddess Athena by one of the giants during the Gigantomachia. She caught up the beast and threw up to the pole of heaven to form the Constellation Draco. It should be noted that the heavenly Drakon was usually identified as the Hesperian beast, guardian of the golden apples.

Pseudo-Hyginus, Astronomica 2. 3 (trans. Grant) (Roman mythographer C2nd A.D.) :
"Constellation Serpent . . . Some also say this Draco was thrown at Minerva [Athene] by the Gigantes, when she fought them. Minerva [Athena], however, snatched its twisted form and threw it to the stars, and fixed it at the very pole of heaven. And so to this day it appears with twisted body, as if recently transported to the stars."

Sources:

• Hyginus, Astronomica - Latin Mythography C2nd A.D.