constants.hpp File Reference

Named astronomical and time-system constants from tempoch. More...

#include "ffi_core.hpp"

Include dependency graph for constants.hpp:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Namespaces
namespace	tempoch
namespace	tempoch::constants

Functions
double	tempoch::constants::j2000_jd_tt () noexcept
	J2000.0 epoch as a Julian Date in TT (2 451 545.0).
double	tempoch::constants::unix_epoch_jd () noexcept
	Unix epoch as Julian Date on the UTC axis (1970-01-01 midnight UTC).
double	tempoch::constants::unix_epoch_mjd () noexcept
	Unix epoch as Modified Julian Day on the UTC axis (40 587.0).
double	tempoch::constants::julian_year_days () noexcept
	Length of a Julian year in days (365.25 days).
double	tempoch::constants::utc_defined_from_mjd () noexcept
	UTC MJD from which the UTC time scale is defined (1961-01-01, MJD 37300).
double	tempoch::constants::gps_epoch_jd_utc () noexcept
	GPS epoch as a Julian Date in UTC (1980-01-06T00:00:00 UTC, JD 2 444 244.5).
double	tempoch::constants::gps_epoch_jd_tai () noexcept
	GPS epoch as a Julian Date in TAI.
double	tempoch::constants::gps_epoch_tai_minus_utc_seconds () noexcept
	TAI − UTC offset at the GPS epoch in seconds (19 s).
double	tempoch::constants::delta_t_prediction_horizon_mjd () noexcept
	MJD beyond which ΔT predictions are no longer reliable (UTC).
double	tempoch::constants::eop_start_mjd () noexcept
	First MJD covered by the compiled EOP data (UTC).
double	tempoch::constants::eop_end_mjd () noexcept
	Last MJD covered by the compiled EOP data (UTC).
double	tempoch::constants::eop_observed_end_mjd () noexcept
	Last MJD for which compiled EOP data is observed (rather than predicted, UTC).
double	tempoch::constants::modern_delta_t_observed_end_mjd () noexcept
	Last MJD for which modern ΔT observed values are available (UTC).
double	tempoch::constants::tt_minus_tai_seconds () noexcept
	Constant TT − TAI offset in seconds (32.184 s).
double	tempoch::constants::nanos_per_second () noexcept
	Number of nanoseconds in one SI second (1e9).
double	tempoch::constants::iau_time_epoch_t0_jd () noexcept
	IAU time-scale epoch T0 as a Julian Date on the TT axis (1977-01-01 TAI).
double	tempoch::constants::tdb_tt_model_high_accuracy_start_jd () noexcept
	First JD(TT) of the high-accuracy TDB−TT model validity window.
double	tempoch::constants::tdb_tt_model_high_accuracy_end_jd () noexcept
	Last JD(TT) of the high-accuracy TDB−TT model validity window.
double	tempoch::delta_t_seconds (double jd_ut1) noexcept
double	tempoch::delta_t_seconds_extrapolated (double jd_ut1) noexcept

Detailed Description

Named astronomical and time-system constants from tempoch.

Each constant is a thin constexpr or inline wrapper that delegates to the corresponding tempoch-ffi function. Where the FFI function accesses data tables built at compile-time (e.g. EOP start/end MJDs), the wrapper intentionally remains a function rather than a constexpr to avoid ABI coupling.

Definition in file constants.hpp.