IERS Reference Meridian
The IERS Reference Meridian (IRM), also called the International Reference Meridian, is the
It is the reference meridian of the
Location
The most important reason for the 5.3 seconds of longitude offset between the IERS Reference Meridian and the Airy transit circle is that the observations with the transit circle were based on the local vertical, while the IERS Reference is a geodetic longitude, that is, the plane of the meridian contains the center of mass of the Earth.[1]
The International Hydrographic Organization adopted an early version of the IRM in 1983 for all nautical charts.[3] It was adopted for air navigation by the International Civil Aviation Organization on 3 March 1989.[4] Tectonic plates slowly move over the surface of Earth, so most countries have adopted for their maps an IRM version fixed relative to their own tectonic plate as it existed at the beginning of a specific year. Examples include the North American Datum 1983 (NAD83), the European Terrestrial Reference Frame 1989 (ETRF89), and the Geocentric Datum of Australia 1994 (GDA94). Versions fixed to a tectonic plate differ from the global version by at most a few centimetres.
The IERS system is not quite fixed to any point attached to the Earth. For example, all points on the European portion of the Eurasian plate, including the Royal Observatory, are moving northeast at about 2.5 cm per year relative to it. The IRM is the weighted average (in the
List of places
Starting at the North Pole and heading south to the South Pole, the IERS Reference Meridian passes through eight countries:
See also
- 1st meridian east
- 1st meridian west
- 180th meridian
- Coordinated Universal Time
- Prime meridian
- Prime meridian (Greenwich)
References
Notes
- datumis 51°28'40.1247"N.
Citations
- ^ .
- ^ IRM on grounds of Royal Observatory from Google Earth Accessed 30 March 2012
- ^ "A manual on the technical aspects of the United Nations Convention on the Law of the Sea – 1982" (PDF). Archived from the original (PDF) on 2008-09-10. Retrieved 2012-03-28. (4.89 MB) Section 2.4.4.
- ^ WGS 84 Implementation Manual Archived 2008-10-03 at the Wayback Machine page i, 1998
- ^ McCarthy, Dennis D.; Petit, Gérard, eds. (2004), "Conventional Terrestrial Reference System and Frame", IERS Conventions (2003) (Technical report), IERS Technical Note, 32, retrieved 2021-07-23
- ^ ITU Radiocommunication Assembly (2002). "Standard-frequency and time-signal emissions" (PDF). International Telecommunication Union. Retrieved 5 February 2022.