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    Re: Possible limitaion for lunar distance measuremen
    From: Kent Nordström
    Date: 2009 Mar 1, 11:53 +0100

    Referring to [7465] from Frank Reed, [7471] from Wolgang Köberer and [7477] from George Huxtable. Thanks for providing your views on the possible limitations in distance when using the Dunthorne formula. And thanks to Wolgang, who translated the text from the German manual much better than I did. I am not aware what Wolgang will do – ref to George’s question – so I provide the formulas without any intention to interfer in Wolgang’s effort.


    The formula no.18 in the German manual, page 386:



    cos D’ = cos Δ’ +  cos m’ * cos s’  * ( cos D – cos Δ )

                                   cos m * cos s


    (Formel von Dunthorne)



    In the above formula:

    D’ = true distance

    Δ’ = H’ – h’, true values of altitudes

    m’, s’ = H’, h’

    m, s = H, h, apparent values of altitudes

    D = apparent distance

    Δ = H – h, apparent values


    These designations have been taken from another issue of the German manual, I don’t know which because I just have copies of some pages from these manuals.


    The formula no.20



    cos D’ = cos Δ’ - 2 *  cos m’ * cos s’  * sin ½ ( D + Δ ) * sin ½ ( cos D –  Δ )

                                        cos m * cos s




    That is, the formula no.20 is the same as no.18 but put into another form.

    Kent N                          

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