/// <summary> /// Calculates instants of rising, transit and setting for non-stationary celestial body for the desired date. /// Non-stationary in this particular case means that body has fastly changing celestial coordinates during the day. /// </summary> /// <param name="eq">Array of three equatorial coordinates of the celestial body correspoding to local midnight, local noon, and local midnight of the following day after the desired date respectively.</param> /// <param name="location">Geographical location of the observation point.</param> /// <param name="theta0">Apparent sidereal time at Greenwich for local midnight of the desired date.</param> /// <param name="pi">Horizontal equatorial parallax of the body.</param> /// <param name="sd">Visible semidiameter of the body, expressed in degrees.</param> /// <returns>Instants of rising, transit and setting for the celestial body for the desired date.</returns> public static RTS RiseTransitSet(CrdsEquatorial[] eq, CrdsGeographical location, double theta0, double pi = 0, double sd = 0) { if (eq.Length != 3) { throw new ArgumentException("Number of equatorial coordinates in the array should be equal to 3."); } double[] alpha = new double[3]; double[] delta = new double[3]; for (int i = 0; i < 3; i++) { alpha[i] = eq[i].Alpha; delta[i] = eq[i].Delta; } Angle.Align(alpha); Angle.Align(delta); List <CrdsHorizontal> hor = new List <CrdsHorizontal>(); for (int i = 0; i <= 24; i++) { double n = i / 24.0; CrdsEquatorial eq0 = InterpolateEq(alpha, delta, n); var sidTime = InterpolateSiderialTime(theta0, n); hor.Add(eq0.ToTopocentric(location, sidTime, pi).ToHorizontal(location, sidTime)); } var result = new RTS(); for (int i = 0; i < 24; i++) { double n = (i + 0.5) / 24.0; CrdsEquatorial eq0 = InterpolateEq(alpha, delta, n); var sidTime = InterpolateSiderialTime(theta0, n); var hor0 = eq0.ToTopocentric(location, sidTime, pi).ToHorizontal(location, sidTime); if (double.IsNaN(result.Transit) && hor0.Altitude > 0) { double r = SolveParabola(Math.Sin(Angle.ToRadians(hor[i].Azimuth)), Math.Sin(Angle.ToRadians(hor0.Azimuth)), Math.Sin(Angle.ToRadians(hor[i + 1].Azimuth))); if (!double.IsNaN(r)) { double t = (i + r) / 24.0; eq0 = InterpolateEq(alpha, delta, t); sidTime = InterpolateSiderialTime(theta0, t); result.Transit = t; result.TransitAltitude = eq0.ToTopocentric(location, sidTime, pi).ToHorizontal(location, sidTime).Altitude; } } if (double.IsNaN(result.Rise) || double.IsNaN(result.Set)) { double r = SolveParabola(hor[i].Altitude + sd, hor0.Altitude + sd, hor[i + 1].Altitude + sd); if (!double.IsNaN(r)) { double t = (i + r) / 24.0; eq0 = InterpolateEq(alpha, delta, t); sidTime = InterpolateSiderialTime(theta0, t); if (double.IsNaN(result.Rise) && hor[i].Altitude + sd < 0 && hor[i + 1].Altitude + sd > 0) { result.Rise = t; result.RiseAzimuth = eq0.ToTopocentric(location, sidTime, pi).ToHorizontal(location, sidTime).Azimuth; } if (double.IsNaN(result.Set) && hor[i].Altitude + sd > 0 && hor[i + 1].Altitude + sd < 0) { result.Set = t; result.SetAzimuth = eq0.ToTopocentric(location, sidTime, pi).ToHorizontal(location, sidTime).Azimuth; } if (!double.IsNaN(result.Transit) && !double.IsNaN(result.Rise) && !double.IsNaN(result.Set)) { break; } } } } return(result); }
// TODO: docs, tests public static double LongitudeDifference(double eclipticalLongitudeSun, double eclipticalLongitudeBody) { double[] longitudes = new[] { eclipticalLongitudeBody, eclipticalLongitudeSun }; Angle.Align(longitudes); return(longitudes[0] - longitudes[1]); }