A star tracker is one of its reference points (of absolute orientation). There's also a sun sensor with a similar function. I don't know if Voyagers have others

A star tracker is one of its reference points (of absolute orientation). There's also a sun sensor with a similar function. I don't know if Voyagers have others. - "In flight, the device found and locked on to the star Canopus, providing a reference for guidance and navigation." https://airandspace.si.edu/collection-objects/star-tracker-and-hood-assembly-support-equipment-voyager-spacecraft/nasm_A19990065003 https://airandspace.si.edu/collection-objects/star-tracker-a... ("Star Tracker and Hood Assembly Support Equipment, Voyager Spacecraft") https://airandspace.si.edu/collection-objects/sun-sensor-and-hood-assembly-support-equipment-voyager-spacecraft/nasm_A19990065002 https://airandspace.si.edu/collection-objects/sun-sensor-and... ("Sun Sensor and Hood Assembly Support Equipment, Voyager Spacecraft") edit: In more detail, https://space.stackexchange.com/questions/43803/how-did-the-canopus-star-tracker-work-are-there-any-still-out-there-in-service https://space.stackexchange.com/questions/43803/how-did-the-...