Voyager’s attitude system used Canopus as its principal star reference for celestial orientation.
The Voyagers were three-axis-stabilized spacecraft, meaning they controlled rotation around three axes rather than spinning like some earlier probes. Their Attitude and Articulation Control Subsystem combined gyroscopes with celestial references: Sun sensors supplied Sun-based orientation information, while a star tracker watched the bright southern star Canopus for roll reference.
Maintaining attitude was essential because Voyager’s narrow-beam high-gain antenna had to remain pointed toward Earth across billions of kilometers. The spacecraft also needed accurate pointing for its instruments and its movable scan platform during planetary encounters.
Canopus is one of the brightest stars in Earth’s night sky and is especially useful as a stable reference well away from the Sun’s direction. The answer is sometimes blurred by descriptions saying Voyager used “the Sun and Canopus.” That is correct as a system-level summary, but when the question asks which star supplied the reference, Canopus is the single canonical answer.