/// <summary>
/// Converts galactical coodinates to equatorial, for equinox B1950.0.
/// </summary>
/// <param name="gal">Galactical coodinates.</param>
/// <returns>Equatorial coodinates, for equinox B1950.0.</returns>
public static CrdsEquatorial ToEquatorial(this CrdsGalactical gal)
{
CrdsEquatorial eq = new CrdsEquatorial();
double l_l0 = Angle.ToRadians(gal.l - 123.0);
double delta0 = Angle.ToRadians(27.4);
double b = Angle.ToRadians(gal.b);
double Y = Math.Sin(l_l0);
double X = Math.Cos(l_l0) * Math.Sin(delta0) - Math.Tan(b) * Math.Cos(delta0);
double sinDelta = Math.Sin(b) * Math.Sin(delta0) + Math.Cos(b) * Math.Cos(delta0) * Math.Cos(l_l0);
eq.Alpha = Angle.To360(Angle.ToDegrees(Math.Atan2(Y, X)) + 12.25);
eq.Delta = Angle.ToDegrees(Math.Asin(sinDelta));
return(eq);
}
/// <summary>
/// Converts equatorial coordinates (for equinox B1950.0) to galactical coordinates.
/// </summary>
/// <param name="eq">Equatorial coordinates for equinox B1950.0</param>
/// <returns>Galactical coordinates.</returns>
public static CrdsGalactical ToGalactical(this CrdsEquatorial eq)
{
CrdsGalactical gal = new CrdsGalactical();
double alpha0_alpha = Angle.ToRadians(192.25 - eq.Alpha);
double delta = Angle.ToRadians(eq.Delta);
double delta0 = Angle.ToRadians(27.4);
double Y = Math.Sin(alpha0_alpha);
double X = Math.Cos(alpha0_alpha) * Math.Sin(delta0) - Math.Tan(delta) * Math.Cos(delta0);
double sinb = Math.Sin(delta) * Math.Sin(delta0) + Math.Cos(delta) * Math.Cos(delta0) * Math.Cos(alpha0_alpha);
gal.l = Angle.To360(303 - Angle.ToDegrees(Math.Atan2(Y, X)));
gal.b = Angle.ToDegrees(Math.Asin(sinb));
return(gal);
}
