When you have been taking astro photos and observing for years, you may decide you would like to contribute something useful to astronomy. There are several programs that allow amateur astronomers to make real contributions to astronomy.

Astronomical photoelectric photometry is one area where amateurs can make very significant contributions with very modest equipment and from backyards in large cities. There are many bright stars that are scientifically important, but go unobserved. Major observatories will not allot astronomers time on telescopes because these observations can take days, weeks or even years. In addition,most professional observatories have telescopes that are way too large to observe bright stars. While the telescopes could be stopped down, it would probably be deemed a waste of telescope time. These stars are perfect for small telescopes even in light polluted cities. The major requirement is for the observer to be dedicated and careful with the observations.

Many if not most stars vary in brightness. Photoelectric Photometry is a means of measuring starlight. Star light is extremely feeble. Photoelectric photometers are sensitive enough to measure individual photons. Filters can be used to determine the color (UBV) of the star light.

There are many reasons stars vary in brightness. One is due to binary stars eclipsing each other. Our star, the Sun, is unique in that there is only one star in the system. Most star systems consist of two or more stars revolving around a common center of gravity. Some stars are so close that their surfaces touch and they orbit the center of gravity in a period of hours. Other star systems orbit their center of gravity in years. Even with the largest telescopes, these star systems are too far away to be resolved into separate objects. However, if the plane of the orbiting stars is close to the Earth's location, observations from Earth can be made when the stars pass in front of each other.

Think of two flashlights held out in each hand at a distance. You see a total of 2 amounts of light from the flashlights. When one flashlight passes behind the other, the amount of light decreases by half. By measuring the light from a star system and plotting the change in brightness over time, an Earth-based observer can glean a great deal of information about the star system without actually having to see the individual stars.

Present Page Version as of 6 May 2005

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