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    Re: Compass Rose
    From: Dan Hogan
    Date: 2001 Mar 24, 12:02 PM

    On 24 Mar 2001, at 8:59, Edgar Kitchin wrote:
    >   Then there is the system that one no longer sees which had the form "N
    >   45 E", "S 20 W" etc. for which I can't see any advantages but presumably
    >   they some at sometime.
    The above system is the result of using "the Law of Cosines" formula for
    sight reduction. HO 208 and many of the pre-WWII short tables give the
    answer in reference to N/S__W/E of the quadrant. These required
    memorizing a set of "rules" to use them.
    Let L= latitude                         h= altitude
            d= declination                  Z= azimuth
            t= local hour angle
            h= sin<-1> (cos L x cod d x  cos t + sin x sin d)
            Z= sin<-1> (cos d x sin t / cos h)
    The above formulas can be worked with an pocket calculator or, if you
    really want to work, with a set if Trig Tables. Most are described in pre-
    1995 navigation manuals.
    Dan Hogan WA6PBY
    Catalina 27 "GACHA"
    Navigation-L List Owner

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