Module scales 

Astronomical time scales.

Provides implementations of the eight primary time scales used in astronomical calculations: UTC, TAI, TT, UT1, GPS, TDB, TCB, and TCG.

Time Scale Overview

Scale	Description	TAI Relationship
TAI	International Atomic Time	Reference
UTC	Coordinated Universal Time	TAI - leap seconds
TT	Terrestrial Time	TAI + 32.184s
UT1	Earth rotation time	Requires EOP data
GPS	GPS satellite time	TAI - 19s
TCG	Geocentric Coordinate Time	Linear scale from TT
TDB	Barycentric Dynamical Time	TT + periodic terms
TCB	Barycentric Coordinate Time	Linear scale from TDB

Usage

Each time scale is a newtype wrapping a Julian Date. Create instances via from_julian_date or *_from_calendar helper functions:

use celestial_time::{JulianDate, TAI, TT, UTC};
use celestial_time::scales::{tai_from_calendar, tt_from_calendar};

// From Julian Date
let tai = TAI::from_julian_date(JulianDate::new(2451545.0, 0.0));

// From calendar components
let tt = tt_from_calendar(2000, 1, 1, 12, 0, 0.0);

Conversions

Convert between scales using traits from the conversions submodule:

use celestial_time::{JulianDate, GPS, TAI, TT};
use celestial_time::scales::conversions::{ToTAI, ToTT, ToGPS};

let tai = TAI::from_julian_date(JulianDate::new(2451545.0, 0.0));
let tt = tai.to_tt().unwrap();
let gps = tai.to_gps().unwrap();

Some conversions chain through intermediate scales internally. For example, GPS to TT converts GPS -> TAI -> TT.

Precision

All time scales use split Julian Date storage (jd1, jd2) to preserve nanosecond precision. When adding offsets, the offset is applied to the smaller-magnitude component.

Re-exports

pub use gps::gps_from_calendar;

pub use gps::GPS;

pub use tai::tai_from_calendar;

pub use tai::TAI;

pub use tcb::tcb_from_calendar;

pub use tcb::TCB;

pub use tcg::tcg_from_calendar;

pub use tcg::TCG;

pub use tdb::tdb_from_calendar;

pub use tdb::TDB;

pub use tt::tt_from_calendar;

pub use tt::TT;

pub use ut1::ut1_from_calendar;

pub use ut1::UT1;

pub use utc::utc_from_calendar;

pub use utc::UTC;

pub use conversions::ToTAI;

pub use conversions::ToTCB;

pub use conversions::ToTCG;

pub use conversions::ToTCGFromTCB;

pub use conversions::ToTDB;

pub use conversions::ToTT;

pub use conversions::ToTTFromTDB;

Modules

common

conversions

Time scale conversions between astronomical time systems.

gps

GPS Time scale.

tai

International Atomic Time (TAI) scale.

tcb

Barycentric Coordinate Time (TCB) representation.

tcg

Geocentric Coordinate Time (TCG) time scale.

tdb

Barycentric Dynamical Time (TDB) scale.

tt

Terrestrial Time (TT) time scale.

ut1

Universal Time UT1 time scale.

utc

Coordinated Universal Time (UTC) representation.