Diff: sgp4sdp4/solar.c

Revision:

0:0a841b89d614

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sgp4sdp4/solar.c	Mon Oct 11 10:34:55 2010 +0000
@@ -0,0 +1,69 @@
+/*
+ * 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 = SGPAU*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*/
+
+/*------------------------------------------------------------------*/