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The Gaithersburg Latitude Observatory, in Gaithersburg, Maryland is one of the system of six International Latitude Observatories and (as of 2007) the only National Historic Landmark in Gaithersburg, Maryland.〔(PDF list ) of National Historic Landmarks in Maryland, at the National Park Service website〕 The building is in the National Register of Historic Places.〔(Montgomery County listings ) at (National Register of Historic Places )〕 The GLO was constructed by Edwin Smith, chief of the Instrument Division of the U.S. Coast and Geodetic Survey.〔(National Park Service page about the Observatory )〕 The Gaithersburg Latitude Observatory was one of six observatories — and one of the four original observatories built by 1899〔Publications of the Astronomical Society of the Pacific, (Volume XI, Number 66 ), 1899, pp 231–239〕 — tracking the degree of "wobble" occurring on the earth’s north-south axis and resultant variation of latitude. The Observatory — along with observatories in Cincinnati, Ohio; Ukiah, California; Mizusawa, Japan; Charjui in Russian Turkestan; and Carloforte, Sardina, Italy — performed in concert to carry out a coordinated program of star observation designed to investigate and calculate the degree of earth “wobble” or latitude variation.〔 On the grounds of the Gaithersburg Latitude Observatory stands a plaque that reads: :“This small framed structure played a key role in the scientific investigation of the Earth’s rotation. In 1898, the International Geodetic Association established a network of observatories to measure the wobble of the planet on its axis by plotting the locations of specific stars. This hilltop in Gaithersburg was chosen together with sites in California, Italy, Japan, and the Soviet Union. All five lay along the same latitude (39° 8’ N). The American Stations were supervised by the U.S. Coast and Geodetic Survey. The observatory’s roof was designed to part in the middle on two sets of tracks to expose the reflecting telescope inside to the night sky. Its slatted exterior walls stabilize the inside air to limit the effects of the temperatures on the accuracy of the telescope. The building’s white paint minimizes heat retention that creates air turbulence around the telescope at night, distorting the stars. Knowledge gained from the observations recorded here nightly until 1982 assisted scientists in the study of the Earth’s geophysical make-up and aided spacecraft orbiting the planet and navigating the universe.” A second portion of the observatory was constructed to house the Photographic Zenith Tube. The observers used the Photographic Zenith Tube to capture picture data using the Zenith telescope as a guide of alignment and star track.〔(Geodesy: Latitude Observations with Photographic Zenith Tube at Gaithersburg MD ), Special Publication 27, by Frank E. Ross, PhD. US Coast and Geodetic Survey, US Department of Commerce, 1915; (this page ) contains a photograph of the building with the second portion intact.〕 However, nothing now remains of this addition to the Gaithersburg Latitude Observatory. ==History== The Gaithersburg observatory was established as part of the International Polar Motion Service in 1899. The Gaithersburg observatory was built by Edwin Smith, chief of the Instrument Division of the U.S. Coast and Geodetic Survey, who had conducted similar measurements as a volunteer in 1891-92 from his home in Rockville, Maryland. During its operation twelve groups of stars were studied in the program, each group containing six pairs of stars. Each night, the station observed two of the star groups along a preset schedule and later compared the data against the measurements taken by the five sister stations. The station operated on this schedule until 1915, when it was temporarily closed as a result of economy measures. Operations resumed in 1932 and continued until 1982 when advances in computer technology and satellite observations rendered it obsolete, although data collected by the observatory 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. . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gaithersburg Latitude Observatory」の詳細全文を読む スポンサード リンク
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