solar.c 2.05 KB
 Jeroen Vreeken committed Oct 08, 2012 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 ``````/* * Unit Solar * Author: Dr TS Kelso * Original Version: 1990 Jul 29 * Current Revision: 1999 Nov 27 * Version: 1.30 * Copyright: 1990-1999, All Rights Reserved * * Ported to C by: Neoklis Kyriazis April 1 2001 */ #include "sgp4sdp4.h" /* Calculates solar position vector */ void Calculate_Solar_Position(double _time, vector_t *solar_vector) { double mjd,year,T,M,L,e,C,O,Lsa,nu,R,eps; mjd = _time - 2415020.0; year = 1900 + mjd/365.25; T = (mjd + Delta_ET(year)/secday)/36525.0; M = Radians(Modulus(358.47583 + Modulus(35999.04975*T,360.0) - (0.000150 + 0.0000033*T)*Sqr(T),360.0)); L = Radians(Modulus(279.69668 + Modulus(36000.76892*T,360.0) + 0.0003025*Sqr(T),360.0)); e = 0.01675104 - (0.0000418 + 0.000000126*T)*T; C = Radians((1.919460 - (0.004789 + 0.000014*T)*T)*sin(M) + (0.020094 - 0.000100*T)*sin(2*M) + 0.000293*sin(3*M)); O = Radians(Modulus(259.18 - 1934.142*T,360.0)); Lsa = Modulus(L + C - Radians(0.00569 - 0.00479*sin(O)),twopi); nu = Modulus(M + C,twopi); R = 1.0000002*(1 - Sqr(e))/(1 + e*cos(nu)); eps = Radians(23.452294 - (0.0130125 + (0.00000164 - 0.000000503*T)*T)*T + 0.00256*cos(O)); R = AU*R; solar_vector->x = R*cos(Lsa); solar_vector->y = R*sin(Lsa)*cos(eps); solar_vector->z = R*sin(Lsa)*sin(eps); solar_vector->w = R; } /*Procedure Calculate_Solar_Position*/ /*------------------------------------------------------------------*/ /* Calculates stellite's eclipse status and depth */ int Sat_Eclipsed(vector_t *pos, vector_t *sol, double *depth) { double sd_sun, sd_earth, delta; vector_t Rho, earth; /* Determine partial eclipse */ sd_earth = ArcSin(xkmper/pos->w); Vec_Sub(sol,pos,&Rho); sd_sun = ArcSin(__sr__/Rho.w); Scalar_Multiply(-1,pos,&earth); delta = Angle(sol,&earth); *depth = sd_earth - sd_sun - delta; if( sd_earth < sd_sun ) return( 0 ); else if( *depth >= 0 ) return( 1 ); else return( 0 ); } /*Function Sat_Eclipsed*/ /*------------------------------------------------------------------*/``````