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light curve

Magnitudes: Measuring the Brightness of Stars

On our website, you'll find frequent reference to the term "magnitude" -- this is a unit of measurement of how bright a star looks to us in the sky.  But what does it mean?

The following explanation of what the magnitude measurement scale is and how it was invented is taken from the AAVSO's education project Variable Star Astronomy, Chapter 2:

Mira Variables with Period Changes

Mira variables are the longest-observed class of stars for which we have long-term quantitative data that allow us to study their behavior over centuries-long periods of time.  Fortunately for us, they're also easy to observe and monitor, having some of the largest amplitudes of all variables, and hundreds of them are bright enough that they're within reach of astronomers with modest telescopes.

Historical Light Curves

Historical light curves provide an interesting study of the long-term behavioral changes exhibited in some stars. The AAVSO is a unique resource for variable star research because it contains millions of variable star observations dating back to before the organization was founded in 1911.

About Light Curves

Light curves are fundamental tools for variable star astronomy. They are relatively simple and easy to grasp. They are simply graphs of brightness (Y axis) vs. time (X axis). Brightness increases as you go up the graph and time advances as you move to the right. 

Here is a light curve of a variable star called epsilon Aurigae:

Overview: Long-term visual light curves

Overview: Long-term visual light curves

This page gives background on our long-term visual data archives, with an emphasis on our data holdings for different classes of variable stars.  It is meant to give an overview of the AAVSO International Database (AID) to researchers interested in studying a number of different light curves of a given class, or who are interested in a summary of what the AAVSO's visual data archives have to offer.

Data Access

The AAVSO Data Access portal

Go to Data Download.
Go to WebObs (search observations).
Go to Light Curve Generator.
Go to Data Usage Guidelines.
Go to Information about AAVSO Data.

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