public static function Sat_Eclipsed(Predict_Vector $pos, Predict_Vector $sol, &$depth)
{
$Rho = new Predict_Vector();
$earth = new Predict_Vector();
/* Determine partial eclipse */
$sd_earth = Predict_Math::ArcSin(Predict::xkmper / $pos->w);
Predict_Math::Vec_Sub($sol, $pos, $Rho);
$sd_sun = Predict_Math::ArcSin(Predict::__sr__ / $Rho->w);
Predict_Math::Scalar_Multiply(-1, $pos, $earth);
$delta = Predict_Math::Angle($sol, $earth);
$depth = $sd_earth - $sd_sun - $delta;
if ($sd_earth < $sd_sun) {
return 0;
} else {
if ($depth >= 0) {
return 1;
} else {
return 0;
}
}
}
public static function Calculate_Obs($_time, Predict_Vector $pos, Predict_Vector $vel, Predict_Geodetic $geodetic, Predict_ObsSet $obs_set)
{
$obs_pos = new Predict_Vector();
$obs_vel = new Predict_Vector();
$range = new Predict_Vector();
$rgvel = new Predict_Vector();
self::Calculate_User_PosVel($_time, $geodetic, $obs_pos, $obs_vel);
$range->x = $pos->x - $obs_pos->x;
$range->y = $pos->y - $obs_pos->y;
$range->z = $pos->z - $obs_pos->z;
$rgvel->x = $vel->x - $obs_vel->x;
$rgvel->y = $vel->y - $obs_vel->y;
$rgvel->z = $vel->z - $obs_vel->z;
$range->w = sqrt($range->x * $range->x + $range->y * $range->y + $range->z * $range->z);
$sin_lat = sin($geodetic->lat);
$cos_lat = cos($geodetic->lat);
$sin_theta = sin($geodetic->theta);
$cos_theta = cos($geodetic->theta);
$top_s = $sin_lat * $cos_theta * $range->x + $sin_lat * $sin_theta * $range->y - $cos_lat * $range->z;
$top_e = -$sin_theta * $range->x + $cos_theta * $range->y;
$top_z = $cos_lat * $cos_theta * $range->x + $cos_lat * $sin_theta * $range->y + $sin_lat * $range->z;
$azim = atan(-$top_e / $top_s);
/*Azimuth*/
if ($top_s > 0) {
$azim = $azim + Predict::pi;
}
if ($azim < 0) {
$azim = $azim + Predict::twopi;
}
$el = Predict_Math::ArcSin($top_z / $range->w);
$obs_set->az = $azim;
/* Azimuth (radians) */
$obs_set->el = $el;
/* Elevation (radians)*/
$obs_set->range = $range->w;
/* Range (kilometers) */
/* Range Rate (kilometers/second)*/
$obs_set->range_rate = Predict_Math::Dot($range, $rgvel) / $range->w;
/* Corrections for atmospheric refraction */
/* Reference: Astronomical Algorithms by Jean Meeus, pp. 101-104 */
/* Correction is meaningless when apparent elevation is below horizon */
// obs_set->el = obs_set->el + Radians((1.02/tan(Radians(Degrees(el)+
// 10.3/(Degrees(el)+5.11))))/60);
if ($obs_set->el < 0) {
$obs_set->el = $el;
/*Reset to true elevation*/
}
}
