__NOTOC__ The International Latitude Service was created by the International Geodetic Association in 1899 to study variations in

latitude In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at t ...

caused by

polar motion Polar motion of the Earth is the motion of the Earth's rotation, Earth's rotational axis relative to its Earth's crust, crust. This is measured with respect to a reference frame in which the solid Earth is fixed (a so-called ''Earth-centered, Ea ...

precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In o ...

, or "wobble" of the Earth's axis. In 1891, at the meeting of the Permanent Commission of the International Geodetic Association in Florence, Wilhelm Foerster referred to the discovery by Seth Carlo Chandler of the

predicted by

Leonhard Euler Leonhard Euler ( ; ; ; 15 April 170718 September 1783) was a Swiss polymath who was active as a mathematician, physicist, astronomer, logician, geographer, and engineer. He founded the studies of graph theory and topology and made influential ...

in 1765 and his impact on the determination

s. He proposed that the International Geodetic Association implement a systematic study of this important phenomenon. In 1895, the creation of the International Latitude Service was decided by the International Geodesic Association. Its central office was based in Potsdam and headed by Friedrich Robert Helmert. Regular observations began in 1899. After 1916, the operations of the International Latitudes Service continued under the aegis of the Reduced Geodetic Association among Neutral States presided by Raoul Gautier director of Geneva Observatory. The original ''International Latitude Observatories'' were a system of six

observatories An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysics, oceanography and volcanology are examples of disciplines for which observatories have been constructed. Th ...

located near the parallel of 39° 08' north latitude. The alignment of all six stations along the parallel helped the observatories to perform uniform data analysis. The original six observatories were located in: *

Gaithersburg, Maryland Gaithersburg ( ) is a city in Montgomery County, Maryland, United States. At the time of the 2020 United States census, Gaithersburg had a population of 69,657, making it the third-largest incorporated city and the ninth-most populous communit ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Cincinnati, Ohio Cincinnati ( ; colloquially nicknamed Cincy) is a city in Hamilton County, Ohio, United States, and its county seat. Settled in 1788, the city is located on the northern side of the confluence of the Licking River (Kentucky), Licking and Ohio Ri ...

, United States *

Ukiah, California Ukiah ( ; Pomo: ''Yokáya'', meaning "deep valley" or "south valley") is the county seat and largest city of Mendocino County, California, Mendocino County, in the North Coast (California), North Coast region of California. Ukiah had a populati ...

, United StatesHogle, Gene ''NAC Green Book of Pacific Coast Touring'' (1931) National Automobile Club p.43 * Mizusawa, Iwate, Japan * Charjui, Turkmenistan * Carloforte, Italy Twelve groups of stars were studied in the program, each group containing six pairs of stars. Each night, each station observed two of the star groups along a preset schedule and later compared the data against the measurements taken by the sister stations. Economic difficulties and war caused the closings of some of the original stations, though a newer station was created in Uzbekistan after

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. The data collected by the observatories over the years still has use to scientists, and has been applied to studies of polar motion, the physical properties of the Earth, climatology and satellite tracking and

navigation Navigation is a field of study that focuses on the process of monitoring and controlling the motion, movement of a craft or vehicle from one place to another.Bowditch, 2003:799. The field of navigation includes four general categories: land navig ...

. The final six observatories were located, in order of Longitude (E to W), in: *Gaithersburg, Maryland, USA, Gaithersburg Latitude Observatory: *Cincinnati, Ohio, USA: *Ukiah, California, USA: *Mizusawa, Japan, National Institutes of Natural Sciences National Astronomical Observatory of Japan, Mizusawa VERA Observatory: *Kitab, in

Uzbekistan , image_flag = Flag of Uzbekistan.svg , image_coat = Emblem of Uzbekistan.svg , symbol_type = Emblem of Uzbekistan, Emblem , national_anthem = "State Anthem of Uzbekistan, State Anthem of the Republ ...

: *Carloforte, Italy: The ILS was renamed International Polar Motion Service (IPMS) in 1962. It was replaced when the International Earth Rotation Service (IERS) was established in 1987.

References

External links

National Park Service
- ''The history of the Gaithersburg Observatory in Maryland, and the overall project''. {{Authority control Astronomical observatories Astronomical observatories in Italy Astronomical observatories in Japan Astronomical observatories in California Astronomical observatories in Uzbekistan Buildings and structures in Cincinnati Buildings and structures in Mendocino County, California Astronomical observatories in Ohio Astronomical observatories in Maryland Buildings and structures in Gaithersburg, Maryland International geodesy organizations

See also

References

Further reading

External links