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20 Million Observations

On Feburary 19, 2011 the number of observations in the AAVSO International Database surpassed the 20 million mark. It is fitting that this milestone was achieved during our 100th anniversary. Below is some information about the achievement.


A citizen science project running for over 100 years reached a key milestone this month when an amateur astronomer contributed the 20 millionth observation of a variable star on February 19, 2011.

Harvard Designation

The Harvard Designation of Variable Stars

Margaret W. Mayall
This appeared in Vol. 5, No. 1 of the Journal of the AAVSO

The AAVSO International Database

Looking for AAVSO Data?  Go directly to AAVSO Data Access.

The AAVSO International Database has over 28 million variable star observations going back over one hundred years. It is the largest and most comprehensive digital variable star database in the world. Over 1,000,000 new variable star brightness measurements are added to the database every year by over 700 observers from all over the world.


The AAVSO Research Portal

Welcome to the AAVSO's Research Portal.  From this page, you can find information about obtaining AAVSO data, requesting new observations, or learning more about the AAVSO, its data, and its services for the research community.  Its purpose is to facilitate your use of the AAVSO's resources in your research efforts.

See the blue boxes on the right hand side of this page to access the AAVSO data archives or to find out  how to work with the AAVSO to obtain new scientific data.


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