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