Collecting Data

As you are now aware, you have several choices of how you may observe variable stars. You may observe variables using your eyes and make visual comparisons with other stars that you can see through binoculars or the telescope's eyepiece; you may use a CCD and make comparisons with other stars in the image frame using computer software; and you may use a photoelectric method and make comparisons with other stars using mathematical interpolation.

Observing variable stars visually is the fastest method. It is really the only method available to amateurs who wish to make several dozen, or more, observations in one night and for observers who monitor cataclysmic variables (CVs) and wish only to detect the outburst. To detect a CV outburst, you need only use you eyes to detect the brightening of the star. When a cataclysmic variable goes into outburst it is evident and as long as your telescope has the ability to see deep enough, you will be able to detect these interesting outbursts. Also, to adequately monitor long-period, high-amplitude variables, such as the Mira variables, the precision of your eyes is completely satisfactory. You will normally make an observation of these slowly varying stars every two weeks or so and a change of several tenths of a magnitude will be quite evident to a careful observer. Visual observation is probably the fastest way to hunt for supernovae too. Don't think that you need to move on to instruments to completely enjoy variable-star observing. However, should you wish a new challenge, CCD and PEP methods await your attention.

CCD and PEP methods will allow you to observe and study variable stars with subtle variations, invisible to the naked eye, or to discover very fast, faint oscillations within a star's brightness, such as quasi-periodic oscillations (QPOs) in dwarf novae. The use of science filters is strongly encouraged when using instruments. Probably the most important thing about collecting instrument data, especially when filters are used, is that it must be able to be converted into some kind of standard data. In other words, when you use an instrument to collect data, for example a CCD or stellar photometer, the data produced is unique to that instrument and filter and it must be transformed into a universally accepted standard. Think of it this way; all humans will see the same event in a slightly different way just like all machines will detect the same event in a slightly different way. This is the result of imperfect manufacturing methods, non-uniform quality standards, perhaps even minor environmental conditions when the equipment is used and of course, observer induced inconsistencies will always be present to name a few.

Regardless of how you observe, each method will allow you to collect data in a slightly different way and one method should not be thought of as better than another. Each method has advantages over another as well as disadvantages. There is no room for snobbery within the variable-star observing community and no observer should feel compelled to defend their method of observing.

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