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    Re: Position from altitude and azimuth.
    From: Bill Lionheart
    Date: 2020 May 12, 19:11 +0100

    I fixed my calculation in Mathematica which had some small bugs. I
    used the GHAand declination to one decimal place in minutes too.
    Attached is a pdf printout of what I did.
    
    It uses the spherical sine rule and Napier's analogies as I mentioned
    
    On Tue, 12 May 2020 at 18:31, Geoffrey Kolbe
     wrote:
    >
    > What's with all this iteration...?
    >
    > I presented equations for finding LAT and LONG from the measured altitude Ho 
    and measured azimuth Zo of a celestial body back in 2008 at the Mystic 
    navigation conference when I gave a talk about navigating with a theodolite.. 
    I am shocked nobody remembers!
    >
    > In this case, we have Ho = 54° 56', Zo = 120° 28' . The DEC for the sun was 
    16° 46.9' and the GHA was 45° 51'
    >
    > Let MA = Sin-1(Sin Zo · Cos Ho / Cos DEC) = 31° 09'
    >
    > Since Zo is < 180, LHA = 360 - MA = 328° 51', from which we get a longitude 
    of 77° West in the usual way
    >
    > We can find the latitude from:
    >
    > LAT = Sin-1[(Sin Ho·Sin DEC - Cos Ho·Cos DEC·Cos MA·Cos Zo)/(1 - (Cos DEC·Sin MA)2)] = 39° North
    >
    > The end
    >
    > Geoffrey Kolbe
    >
    > View and reply to this message
    
    

    File: 147796.napiersphericaltrig.pdf
       
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