orbit_time.cpp

#include "orbit_time.h"

double Ot::convert_GDs_to_MJD(orbit_date input_time) {
	int a{ (14 - input_time.mounts) / 12 };
	int y{ input_time.years + 4800 - a };
	int m{ input_time.mounts + 12 * a - 3 };

	return (input_time.days + (153 * m + 2) / 5 + 365 * y + y / 4 - y / 100 + y / 400 - 32045 +
		double(input_time.hours - 12) / double(24) + double(input_time.min) / double(1440) + double(input_time.sec) / double(86400));
}

double Ot::getCurrent_TDB(double time_zone) {
	double TT{ getCurrent_TT(time_zone) };
	double d{ (TT - 51544.5) / 36525.0 };
	double g{ 0.017453 * (357.258 + 35999.05 * d) };
	return (TT + (0.001658 * sin(g + 0.0167 * sin(g)) / 86400));
}

double Ot::GMST(double deltaUT)
{
	assert(deltaUT <= 0.9);
	double ts = getCurrent_MJD() + deltaUT / double(86400);
	double Tu = (int(ts) - 51544.5) / 36525;
	double S0 = 1.753368559233266 + (628.3319706888409+(6.770714*pow(10,-6) - 4.51*pow(10,-10)*Tu) * Tu) * Tu;
	double r = 6.300388098984891 + (3.707456 * pow(10, -10) - 3.707 * pow(10, -14) * Tu) * Tu;
	return (S0 + r*(ts - int(ts)));
}

double Ot::GTST(double inputGMST)
{
	m_matrix.settime(getCurrent_MJD());
	return (inputGMST + m_matrix.getΔψ()*cos(m_matrix.getε()));
}

double Ot::convert_TT_to_TDB(double input_time) {
	double d{ (input_time - 51544.5) / 36525.0 };
	double g{ 0.017453 * (357.258 + 35999.05 * d) };
	return (input_time + (0.001658 * sin(g + 0.0167 * sin(g)) / 86400));
}