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    Re: Raw data for bubble
    From: Peter Fogg
    Date: 2007 Mar 20, 10:29 +1100
    Bill

    From my text "Field Astronomy for Surveyors", pp143:
    [Separate observations at] "the local meridian and the prime vertical" [leads to] "the effects of systematic and random errors of the quantities sought" [being] "kept to a minimum."

    This, apparently, was the main reason for the recommendation to surveyors of making separate observations for latitude and longitude. Less error equals more accuracy.

    Of course they were making their observations from a fixed place, rather than a moving one.

    These words are in the introduction to a chapter entitled:
    "The Simultaneous Determination of Latitude and Longitude"
    that, among other matters, looks at how such error can be dealt with.

    For myself the appeal of these separate observations is that they are a relatively simple and elegant means of establishing position. Another advantage, for those who are worried by ambiguity, is that there is none - a single line of position is derived in each case, establishing latitude and longitude, leading to an unambiguous fix.

    It is interesting to look at your calculations and see how little difference in azimuth results from a relatively gross (one degree) error in latitude. It seems that a reasonably good idea of longitude could still be achieved with such a poor idea of latitude - is that your conclusion?


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