It is not necessary to possess expensive or advanced apparatus in order to begin making accurate measures of double stars. This chapter discusses three different techniques, in ascending order of sophistication: the ring method, the chronometric method, and finally the use of reticle eyepieces. Of these, the ring method is the simplest, requiring in its crudest form nothing more than an ordinary stopwatch with lap facility. By the addition of a crosswire and position angle dial, the observer can begin to measure closer pairs. Even an illuminated reticle eyepiece requires no great financial outlay, and permits observations comparable in accuracy with those achieved using a filar micrometer.
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