independent time argument of JPL ephemerides (Standish, A&A, 336, 381, 1998) that is, for practical purposes, the same as Barycentric Dynamical Time (TDB). TDB is related to Barycentric Coordinate Time (TCB) by
TDB = TCB - L_B × (JD_TCB - T₀) × 86400 + TDB₀, where T₀ = 2443144.5003725, and
L_B = 1.550519768 × 10^-8 and TDB₀ = -6.55 × 10^-5 s
are defining constants. [IAU 2006 Resolution B3]

Source: IERS Technical Note 36: Glossary (PDF, 244KB, Not barrier-free file.) of the IERS Conventions (2010)

see Barycentric Coordinate Time

see Geocentric Coordinate Time

time scale for apparent geocentric ephemerides defined by a 1979 IAU resolution and in 1991 was replaced by Terrestrial Time (TT).

Source: IERS Technical Note 36: Glossary (PDF, 244KB, Not barrier-free file.) of the IERS Conventions (2010)

Original Source: IAU 2006 NFA Glossary

Acronym: TEO

The TEO is defined symmetrically with the CEO on the true terrestrial equator perpendicular to the CIP on the Earth.

Related terms:

• Celestial Ephemeris Origin
• Celestial Intermediate Pole

origin of longitude in the Intermediate Terrestrial Reference System. It is the non-rotating origin in the ITRS that is recommended by the IAU 2000 Resolution B1.8, where it was designated Terrestrial Ephemeris Origin. The name Terrestrial Intermediate Origin was adopted by IAU 2006 Resolution B2. The TIO was originally set at the ITRF origin of longitude and throughout 1900-2100 stays within 0.1 mas of the ITRF zero meridian.

Source: IERS Technical Note 36: Glossary (PDF, 244KB, Not barrier-free file.) of the IERS Conventions (2010)

Original Source: IAU 2006 NFA Glossary

a geocentric reference system defined by the intermediate equator of the CIP and the TIO (IAU 2006 Resolution B2). It is related to the ITRS by polar motion and s′ (see TIO locator). It is related to the Celestial Intermediate Reference System by a rotation of ERA around the CIP, which defines the common z-axis of the two systems. Since the acronym for this system is close to another acronym (namely ITRS), it is suggested that wherever possible the complete name be used.

Source: IERS Technical Note 36: Glossary (PDF, 244KB, Not barrier-free file.) of the IERS Conventions (2010)

Original Source: IAU 2006 NFA Glossary

Realization of the Terrestrial Reference System (TRS), through the realization of its origin, orientation axes and scale, and their time evolution.

Source: IERS Technical Note 36: Glossary (PDF, 244KB, Not barrier-free file.) of the IERS Conventions (2010)

A Terrestrial Reference System (TRS) is a spatial reference system corotating with the Earth in its diurnal motion in space.

Source: IERS Technical Note 36: Glossary (PDF, 244KB, Not barrier-free file.) of the IERS Conventions (2010)

Acronym: TT

TT is the coordinate time at the surface of the Earth.

TT is conventionally realized by TT = TAI + 32.184 s (although in fact TAI and TT are independent time scales, and different implementations of TT may differ by a few tens of microseconds.)

Related terms:

• Barycentric Coordinate Time
• Geocentric Coordinate Time