See also: AAVSO Manual for Visual Observing of Variable Stars

There are many reasons why the collection of data on variable stars is an important and useful activity. An observation of variable stars is the one aspect of modern day astronomy where the amateur, armed with an affordable equipment, can make a valuable contribution to astronomy science.

Variable stars need to be observed over decades to determine their long-term behaviour. This activity becomes even more rewarding when professional astronomers request the data collected by amateurs.

Moreover, combining actual data with data collected years ago in the past will improve period accuracy and may potentially reveal other effects.

Professional astronomers usually do not have enough time, or the telescope access, to monitor so many stars over long periods. In a case when a particular star starts to exhibit unusual behaviour, amateurs can alert professionals to pay attention to that object, possibly resulting in time allocation on powerful telescopes and scientific support.

Generally, periods determination can lead to a better understanding of the pulsation mechanism of stars. Research on variable stars also provides an information basis for their properties (like mass, radius, luminosity, temperature, even internal and external structure). Some of this information would be difficult or impossible to obtain any other way and can often be used to understand other stars' behavior.

Building O-C diagrams (Observed-Calculated diagrams) can tell us about systems that are changing. These diagrams show the differences between the expected time of minimum of a system and the actual time of minimum in a new observation.

The AAVSO Manual for Visual Observing of Variable Stars is a comprehensive guide to variable star observing. Included is a lot of information and tips on how to make variable star observations and report them to the AAVSO. The Manual is available online in PDF format.

• Variable Stars Easy to Observe
• Variable Star Charts
• Classification of Variable Stars
• AAVSO: Variable Star of the Season Archive