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    Re: Doniol for time sight reduction?
    From: Greg Rudzinski
    Date: 2015 May 15, 12:12 -0700

    Francis,

    The most elegant time sight formula to try and modify to all haversines would be the formula used in Rust's 1918 Practical Tables for Navigators and Aviators.

    hav t = (Cos (Lat. ~ Dec.) - Sin Ho) / 2 Cos Lat. Cos Dec.

    ~ same name (Lat. - Dec.)    ~ contrary name (Lat. + Dec.)

    If Lars is watching then maybe he can work up something that will look good.

    Greg Rudzinski

    From: Francis Upchurch
    Date: 2015 May 15, 07:59 -0700

    Question for I think Hanno +/-Greg.

    Could the Doniol method be adapted for the Time sight reduction? I've been playing around with Fuller slide rule using the cosine formula

    cos(LHA)=[sin(alt) - sin(dec)·sin(lat)]/[cos(dec)·cos(lat)].

    Works fine but takes longer than LOP (Hc) using Bygrave or Brown-Nassau.

    I like the old 19th century methods using trig logs and haversines, the formula I have is hav.LAT=logsec.lat+logcsc.p+logcos.s+logsin(s-alt). where p=polar dist and s=1/2sum. I would be interested to know if Doniol could do it?

    Best wishes

    Francis

       
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