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SuperNOVAS v1.5
The NOVAS C library, made better
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Various functions for calculating the equator and equinox of date, and related quatities. More...
Functions | |
double | accum_prec (double t) |
Returns the general precession in longitude (Simon et al. | |
short | cel_pole (double jd_tt, enum novas_pole_offset_type type, double dpole1, double dpole2) |
int | e_tilt (double jd_tdb, enum novas_accuracy accuracy, double *restrict mobl, double *restrict tobl, double *restrict ee, double *restrict dpsi, double *restrict deps) |
(primarily for internal use) Computes quantities related to the orientation of the Earth's rotation axis at the specified Julian date. | |
int | fund_args (double t, novas_delaunay_args *restrict a) |
Compute the fundamental (a.k.a. | |
double | ira_equinox (double jd_tdb, enum novas_equinox_type equinox, enum novas_accuracy accuracy) |
Compute the intermediate right ascension of the equinox at the input Julian date, using an analytical expression for the accumulated precession in right ascension. | |
double | mean_obliq (double jd_tdb) |
Computes the mean obliquity of the ecliptic. | |
int | nutation (double jd_tdb, enum novas_nutation_direction direction, enum novas_accuracy accuracy, const double *in, double *out) |
Nutates equatorial rectangular coordinates from mean equator and equinox of epoch to true equator and equinox of epoch. | |
short | precession (double jd_tdb_in, const double *in, double jd_tdb_out, double *out) |
Precesses equatorial rectangular coordinates from one epoch to another using the IAU2006 (P03) precession model of Capitaine et al. | |
Various functions for calculating the equator and equinox of date, and related quatities.
short cel_pole | ( | double | jd_tt, |
enum novas_pole_offset_type | type, | ||
double | dpole1, | ||
double | dpole2 ) |
novas_app_to_hor()
/ novas_hor_to_app()
or else wobble()
.Specifies the unmodeled celestial pole offsets for high-precision applications to be applied to the True of Date (TOD) equator, in the old, pre IAU 2006 methodology. Nonetheless, these offsets should be specified relative to the IAU2006 precession / nutation model to provide a correction to the modeled (precessed and nutated) position of Earth's pole, such those derived from observations and published by IERS.
The call sets the global variables PSI_COR
and EPS_COR
, for subsequent calls to e_tilt()
. As such, it should be called to specify pole offsets prior to legacy NOVAS C equinox-specific calls. The global values of PSI_COR
and EPS_COR
specified via this function will be effective until explicitly changed again.
NOTES:
novas_app_to_hor(),
novas_hor_to_app(), or wobble()
). novas_make_frame()
, the offsets will be applied for the TIRS / ITRS conversion only, and not to the TOD equator per se. REFERENCES:
jd_tt | [day] Terrestrial Time (TT) based Julian date. Used only if 'type' is POLE_OFFSETS_X_Y (2), to transform dx and dy to the equivalent Δδψ and Δδε values. |
type | POLE_OFFSETS_DPSI_DEPS (1) if the offsets are Δδψ, Δδε relative to the IAU 20006 precession/nutation model; or POLE_OFFSETS_X_Y (2) if they are dx, dy offsets relative to the IAU 2000 / 2006 precession-nutation model. |
dpole1 | [mas] Value of celestial pole offset in first coordinate, (Δδψ for or dx) in milliarcseconds, relative to the IAU2006 precession/nutation model. |
dpole2 | [mas] Value of celestial pole offset in second coordinate, (Δδε or dy) in milliarcseconds, relative to the IAU2006 precession/nutation model. |
References POLE_OFFSETS_DPSI_DEPS, and POLE_OFFSETS_X_Y.