Ephemeris functions

Collaboration diagram for Ephemeris functions:

Functions
int32_t	jpllib (double utc, rmatrix *rm, rmatrix *drm)
	Librations from JPL Ephemeris. More...
int32_t	jpllib (double utc, rmatrix &rm, rmatrix &drm)
int32_t	jplnut (double utc, double nuts[])
	Nutations from JPL Ephemeris. More...
int32_t	jplpos (long from, long to, double utc, cartpos *pos)
	Position from JPL Ephemeris. More...
int32_t	jplpos (long from, long to, double utc, cartpos &pos)
int32_t	jplopen ()

Detailed Description

Function Documentation

int32_t jpllib	(	double	utc,
		rmatrix *	rm,
		rmatrix *	drm
	)

Librations from JPL Ephemeris.

Position and Velocity values for Lunar Libration from the JPL Ephemeris

Parameters

utc	Modified julian day of position
rm	Pointer to the rotation matrix that represents Libration motion from Selenocentric (Principal Axis) to ICRF.
drm	Pointer to the rotation matrix that represents derivative Libration motion

{
    return jpllib(utc, *rm, *drm);
}

int32_t jpllib	(	double	utc,
		rmatrix &	rm,
		rmatrix &	drm
	)

    {
    double pvec[6];
    int32_t iretn;

    iretn = jplopen();
    if (iretn < 0)
    {
        return iretn;
    }

    eph_mutex.lock();
    iretn = jpl_pleph(jplephem,utc + JD_MJD_OFFSET,15,0,pvec,1);
    eph_mutex.unlock();
    if (iretn < 0)
    {
        return iretn;
    }

    rm = rm_mmult(rm_change_around_z(pvec[0]),rm_mmult(rm_change_around_x(pvec[1]),rm_change_around_z(pvec[2])));
    drm = rm_mmult(rm_change_around_z(pvec[0]+pvec[3]/86400.),rm_mmult(rm_change_around_x(pvec[1]+pvec[4]/86400.),rm_change_around_z(pvec[2]+pvec[5]/86400.)));
    drm = rm_sub(drm,rm);

    return 0;
}

int32_t jplnut	(	double	utc,
		double	nuts[]
	)

Nutations from JPL Ephemeris.

Longitude and obliquity values and rates.

Parameters

utc	Modified julian day of nutations
nuts	Storage for nutations: psi, epsilon, dpsi, depsilon

{
    double pvec[6];

    if (!std::isfinite(utc))
    {
        return JPLEPHEM_ERROR_OUTOFRANGE;
    }

    int32_t iretn = jplopen();
    if (iretn < 0)
    {
        return iretn;
    }

    eph_mutex.lock();
    iretn = jpl_pleph(jplephem,utc + JD_MJD_OFFSET,static_cast<int>(JPL_NUTATIONS),0,pvec,1);
    eph_mutex.unlock();
    if (iretn < 0)
    {
        return iretn;
    }

    nuts[0] = pvec[0];
    nuts[1] = pvec[1];
    nuts[2] = pvec[2] / 86400.;
    nuts[3] = pvec[3] / 86400.;

    return 0;
}

int32_t jplpos	(	long	from,
		long	to,
		double	utc,
		cartpos *	pos
	)

Position from JPL Ephemeris.

Position, velocity and acceleration vectors from one solar system object to another in J2000 coordinates.

Parameters

from	Starting object for vectors.
to	Ending object for vectors.
pos	Storage from returned vectors
utc	Modified julian day of position

{
    return jplpos(from, to, utc, *pos);
}

int32_t jplpos	(	long	from,
		long	to,
		double	utc,
		cartpos &	pos
	)

    {
    static double pvec[3][6];

    pos.s = pos.v = pos.a = rv_zero();

    int32_t iretn = jplopen();
    if (iretn < 0)
    {
        return iretn;
    }

    eph_mutex.lock();
    iretn = jpl_pleph(jplephem,utc + JD_MJD_OFFSET - .05/86400., static_cast<int>(to), static_cast<int>(from) ,pvec[0],1);
    eph_mutex.unlock();
    if (iretn < 0)
    {
        return iretn;
    }

    eph_mutex.lock();
    iretn = jpl_pleph(jplephem,utc + JD_MJD_OFFSET, static_cast<int>(to), static_cast<int>(from) ,pvec[1],1);
    eph_mutex.unlock();
    if (iretn < 0)
    {
        return iretn;
    }

    eph_mutex.lock();
    iretn = jpl_pleph(jplephem,utc + JD_MJD_OFFSET + .05/86400., static_cast<int>(to), static_cast<int>(from) ,pvec[2],1);
    eph_mutex.unlock();
    if (iretn < 0)
    {
        return iretn;
    }

    pos.s.col[0] = pvec[1][0] * 1000.;
    pos.s.col[1] = pvec[1][1] * 1000.;
    pos.s.col[2] = pvec[1][2] * 1000.;
    pos.v.col[0] = pvec[1][3] * 1000.;
    pos.v.col[1] = pvec[1][4] * 1000.;
    pos.v.col[2] = pvec[1][5] * 1000.;
    pos.a.col[0] = (pvec[2][3] - pvec[0][3]) * 10000.;
    pos.a.col[1] = (pvec[2][4] - pvec[0][4]) * 10000.;
    pos.a.col[2] = (pvec[2][5] - pvec[0][5]) * 10000.;
    pos.utc = utc;

    return 0;
}

int32_t jplopen

(

)

{
    if (jplephem == nullptr)
    {
        string fname;
        int32_t iretn = get_cosmosresources(fname);
        if (iretn < 0)
        {
            return iretn;
        }
        fname +=  "/general/lnx1900.405";
        jplephem = jpl_init_ephemeris(fname.c_str(),nullptr,nullptr);
        if (jplephem == nullptr)
        {
            return -errno;
        }
    }
    return 0;
}