/// <summary>
/// Calculates the aberration effect for a celestial body (star or planet) for given instant.
/// </summary>
/// <param name="ecl">Ecliptical coordinates of the body (not corrected).</param>
/// <param name="ae">Aberration elements needed for calculation of aberration correction.</param>
/// <returns>Returns aberration correction values for ecliptical coordinates.</returns>
/// <remarks>
/// AA(II), formula 23.2
/// </remarks>
public static CrdsEcliptical AberrationEffect(CrdsEcliptical ecl, AberrationElements ae)
{
double thetaLambda = Angle.ToRadians(ae.lambda - ecl.Lambda);
double piLambda = Angle.ToRadians(ae.pi - ecl.Lambda);
double beta = Angle.ToRadians(ecl.Beta);
double dLambda = (-k * Math.Cos(thetaLambda) + ae.e * k * Math.Cos(piLambda)) / Math.Cos(beta);
double dBeta = -k *Math.Sin(beta) * (Math.Sin(thetaLambda) - ae.e * Math.Sin(piLambda));
return(new CrdsEcliptical(dLambda / 3600, dBeta / 3600));
}
/// <summary>
/// Calculates the aberration effect for a celestial body (star or planet) for given instant.
/// </summary>
/// <param name="eq">Equatorial coordinates of the body (not corrected).</param>
/// <param name="ae">Aberration elements needed for calculation of aberration correction.</param>
/// <returns>Returns aberration correction values for equatorial coordinates.</returns>
/// <remarks>AA(II), formula 23.3</remarks>
public static CrdsEquatorial AberrationEffect(CrdsEquatorial eq, AberrationElements ae, double epsilon)
{
double a = Angle.ToRadians(eq.Alpha);
double d = Angle.ToRadians(eq.Delta);
double theta = Angle.ToRadians(ae.lambda);
double pi = Angle.ToRadians(ae.pi);
epsilon = Angle.ToRadians(epsilon);
double da = -k * (Math.Cos(a) * Math.Cos(theta) * Math.Cos(epsilon) + Math.Sin(a) * Math.Sin(theta)) / Math.Cos(d)
+ epsilon * k * (Math.Cos(a) * Math.Cos(pi) * Math.Cos(epsilon) + Math.Sin(a) * Math.Sin(pi)) / Math.Cos(d);
double m = Math.Tan(epsilon) * Math.Cos(d) - Math.Sin(a) * Math.Sin(d);
double dd = -k * (Math.Cos(theta) * Math.Cos(epsilon) * m
+ Math.Cos(a) * Math.Sin(d) * Math.Sin(theta))
+ epsilon * k * (Math.Cos(pi) * Math.Cos(epsilon) * m + Math.Cos(a) * Math.Sin(d) * Math.Sin(pi));
return(new CrdsEquatorial(da / 3600, dd / 3600));
}
