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    Re: Azimuth and Declination formulae
    From: Fred Hebard
    Date: 2005 Jul 14, 22:35 -0400

    On Jul 14, 2005, at 8:29 PM, Peter Fogg wrote:
    
    > Along the way, I found a formula for the calculation of the Sun's
    > declination:
    >
    > Dec = 23.45 sin (360/365.25)
    > Its such a simple formula even I can understand it. Its the maximum
    > declination of the sun expressed as a proportion of its change.
    >
    > Here's another version:
    >
    > Dec/23.45 = sin(0.985*t)
    >
    > 0.985 is a truncated version of (360/365.25)
    > and t = the number of days from the vernal equinox
    > or
    > t = (inv sin(Dec/23.45))/(360/365.25)
    >
    > These formulae come from:
    > www.geomancy/org./sunfinder
    
    It's more accurate to use the length of the season as one quarter of a
    circle, but even then there are errors.  The reason for this is that
    summer is longer than winter, about 93 days versus 87.
    
    
    

       
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