American Association of Variable Star Observers
Cambridge, MA 02238
The AAVSO was founded in 1911 at Harvard College Observatory to coordinate variable star observations made largely by amateur astronomers. In 1954, the AAVSO became an independent, private research organization. Today with members in more than 40 countries, over 10 million observations to date, and headquarters in Cambridge, Massachusetts, it is the world’s largest association of variable star observers in existence.