American Association of Variable Star Observers
founded 1911
The American Association of Variable Star Observers (AAVSO) is an international non-profit organization of variable star observers whose mission is "to enable anyone, anywhere, to participate in scientific discovery through variable star astronomy."
They carry out the following activities: observation and analysis of variable stars---collecting and archiving observations for worldwide access---forging strong collaborations between amateur and professional astronomers---promoting scientific research, education, and public outreach using variable star data.
The origins of the AAVSO date to 1911. Edward C. Pickering, director of the Harvard College Observatory (HCO) published a HCO Circular no. 166 (June 1911) in which he announced stars to be observed and listed cooperating variable star observers who were both professional and amateur astronomers. One of these was William Tyler Olcott, who in March 1911 had published an article in Popular Astronomy about variable star work for amateurs. By the end of 1911, Tyler Olcott was coordinating this work of amateurs for the benefit of the HCO.
The AAVSO was incorporated in 1918 as an independent scientific and educational organization in Massachusetts.
Thomas R. Williams and Michael Saladyga, Advancing Variable Star Astronomy: The Centennial History of the AAVSO (Cambridge: Cambridge University Press, 2011 )