The Observatory

The Observatory (HM12LP)

Location: Gaithersburg, MD 20877 Montgomery County
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Country: United States of America
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N 39° 8.202', W 77° 11.915'

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Latitude Observatory Park

U.S. Coast and Geodetic Survey Assistant, Edwin Smith or Rockville, Maryland, was assigned to oversee construction and operations at the Gaithersburg Observatory. Original plans for the Ukiah and Gaithersburg Observatories, prepared by the Central Bureau in Germany, specified that the buildings be constructed of iron. When Mr. smith learned that replicas of the Japanese and Italian Stations could not be built with the projected budget, he revised the plans,substituting wood for the specified iron.

The construction of the Gaithersburg Latitude Observatory was completed in August 1899 and it recieved its Zenith Telescope (ZT) in September of that same year. The facility offically opened on October 18, 1899.

The Gaithersburg Observatory was constructed with a double wall of Georgia and Virginia pine to minimize the difference between the interior and exterior temperatures; a difference that might affect the heat-sensitive Zenith Telescope. The roof was designed in two parts that move east and west on iron wheels operated manually by a rope pulley system within the building. The six-foot, six-inch full opening was always used at Gaithersburg to accommodate the large Zenith Telescope. This type of telescope points at the zenith, or the direction pointing straight above a particular location. Zenith Telescopes are fitted with extremely sensitive spirit bubble levels to facilitate the accurate angle measurements required in the determination of astronomic latitude. The motion-sensitive ZT is mounted on a pier sunk into the ground to negate any vibrations transmitted from surrounding sources like traffic or trains.

The small size of the building and the esoteric character of the work that took place within speak modestly of the international importance of this landmark. The research conducted here provided all the data used in polar motion studies for decades, and fostered international cooperation that transcended the differences between nations during times of war and international strain.

From its construction in 1899 until the obsolence of human observers forced its closing in 1982, the Gaithersburg Latitude Observatory played an integral role in the study of Earth's scientific behavior. Following its closure, the observatory remained unused and began to deteriorate. Fortunately, it was about this same time that the City of Gaithersburg fomralized its historic perservation policies with the adoption of the Historic Preservation Ordinance and designated the observatory as its first officially designated historic site.

The National Oceanographic and Atmospheric Administraion (NOAA) conveyed the abandoned observatory tothe City for historic monument purposes in May 1987, after which the City granted an easment tot he Maryland Historical Trust. Funds were secured for the observatory's restoration and on December 20, 1989, it was deginated a National Historic Landmark. The Gaithersburg International Latitude Obseratory, its Meridian Mark Pier, and five monuments are listed on the National Register of Historic Places.
HM NumberHM12LP
Year Placed2011
Placed ByThe City of Gaithersburg
Marker ConditionNo reports yet
Date Added Monday, September 29th, 2014 at 11:53pm PDT -07:00
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Locationbig map
UTM (WGS84 Datum)18S E 309978 N 4334248
Decimal Degrees39.13670000, -77.19858333
Degrees and Decimal MinutesN 39° 8.202', W 77° 11.915'
Degrees, Minutes and Seconds39° 8' 12.12" N, 77° 11' 54.90" W
Driving DirectionsGoogle Maps
Area Code(s)301, 240, 202
Closest Postal AddressAt or near 2 James St, Gaithersburg MD 20877, US
Alternative Maps Google Maps, MapQuest, Bing Maps, Yahoo Maps, MSR Maps, OpenCycleMap, MyTopo Maps, OpenStreetMap

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