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Mean Local Time of the Ascending Node
by David Eagle
Determines the relationship between mean local time of the ascending node and RAAN.
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| funarg (t)
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function [el, elprim, f, d, omega] = funarg (t)
% this function computes fundamental arguments (mean elements)
% of the sun and moon. see seidelmann (1982) celestial
% mechanics 27, 79-106 (1980 iau theory of nutation).
% t = tdb time in julian centuries since j2000.0 (in)
% el = mean anomaly of the moon in radians
% at date tjd (out)
% elprim = mean anomaly of the sun in radians
% at date tjd (out)
% f = mean longitude of the moon minus mean longitude
% of the moon's ascending node in radians
% at date tjd (out)
% d = mean elongation of the moon from the sun in
% radians at date tjd (out)
% omega = mean longitude of the moon's ascending node
% in radians at date tjd (out)
% Orbital Mechanics with Matlab
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
seccon = 206264.8062470964;
rev = 1296000;
% compute fundamental arguments in arcseconds
arg(1) = ((+0.064 * t + 31.310) * t + 715922.633) * t ...
+ 485866.733 + mod(1325.0 * t, 1.0) * rev;
arg(1) = mod(arg(1), rev);
arg(2) = ((-0.012 * t - 0.577) * t + 1292581.224) * t ...
+ 1287099.8040 + mod(99.0 * t, 1.0) * rev;
arg(2) = mod(arg(2), rev);
arg(3) = ((+0.011 * t - 13.257) * t + 295263.137) * t ...
+ 335778.877 + mod(1342.0 * t, 1.0) * rev;
arg(3) = mod(arg(3), rev);
arg(4) = ((+0.019 * t - 6.891) * t + 1105601.328) * t ...
+ 1072261.307 + mod(1236.0 * t, 1.0) * rev;
arg(4) = mod(arg(4), rev);
arg(5) = ((0.008 * t + 7.455) * t - 482890.539) * t ...
+ 450160.280 - mod(5.0 * t, 1.0) * rev;
arg(5) = mod(arg(5), rev);
% convert arguments to radians
for i = 1:1:5
arg(i) = mod(arg(i), rev);
if (arg(i) < 0.0)
arg(i) = arg(i) + rev;
end
arg(i) = arg(i) / seccon;
end
el = arg(1);
elprim = arg(2);
f = arg(3);
d = arg(4);
omega = arg(5);
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