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Module tcb

celestial_time::scales

Module tcb 

Source
Expand description

Barycentric Coordinate Time (TCB) representation.

TCB is the coordinate time for the barycentric reference frame, as defined by the IAU. It ticks faster than TDB by approximately 1.55e-8 due to gravitational time dilation (Earth sits in the Sun’s gravitational well).

§Relationship to TDB

TCB and TDB are related by a linear transformation plus periodic terms:

TCB - TDB = L_B * (JD_TCB - T_0) * 86400

Where:

  • L_B = 1.550519768e-8 (IAU 2006 Resolution B3)
  • T_0 = 2443144.5003725 (TCB-TDB epoch, 1977 Jan 1.0 TAI)

§Usage

use celestial_time::{JulianDate, TCB};

// Create from Julian Date
let tcb = TCB::from_julian_date(JulianDate::j2000());

// Create from calendar
use celestial_time::scales::tcb::tcb_from_calendar;
let tcb = tcb_from_calendar(2000, 1, 1, 12, 0, 0.0);

// Parse from ISO 8601
let tcb: TCB = "2000-01-01T12:00:00".parse().unwrap();

§When to Use TCB

TCB is the natural time coordinate for barycentric calculations (solar system dynamics, pulsar timing, VLBI). For most terrestrial applications, TDB is more practical since it stays close to TT.

Structs§

TCB
Barycentric Coordinate Time.

Functions§

tcb_from_calendar
Creates TCB from calendar components.