We always hope that the end product of all our hard-earned micrometer measures on a particular system will be the derivation of an orbit from the apparent ellipse and an idea of the total mass in a binary system. It may not be in our lifetime but there is a certain satisfaction from putting down a database of reliable measures that some future researcher will be able to use. Alternatively it is possible to do orbital analysis on systems which have sufficient observations to cover an arc which will allow a good estimate of the apparent ellipse to be made.
Andreas Alzner has gone into the details of orbital analysis in Chapters 7 and 8. Not only professionals, but also skilled and mathematically minded amateurs, like René Manté in France, regularly publish useful new orbital elements (cf. IAU Commission 26 Circulars). It is certainly a challenging occupation and needs a good appreciation of the problems which are posed. Now comes the awful warning. There have been some very bad orbits appearing in print. One had the companion going in the wrong direction and another used an apparent arc of 3° to calculate an orbit of several thousand years and quoted the period to one decimal place into the bargain! In an attempt to counter the proliferation of unhelpful orbits in the literature van den Bos was driven to write a paper called Is this orbit really necessary!
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