United States Naval Observatory
Overview
The United States Naval Observatory (USNO) is one of the oldest scientific agencies in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, with a primary mission to produce Positioning, Navigation, and Timing (PNT) for the U.S. Navy and the U.S. Department of Defense. Located in Northwest Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

, it is one of the pre-1900 astronomical observatories located in an urban area; at the time of its construction, it was far from the light pollution
Light pollution
Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...

 thrown off by the (then-smaller) city center.
Encyclopedia
The United States Naval Observatory (USNO) is one of the oldest scientific agencies in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, with a primary mission to produce Positioning, Navigation, and Timing (PNT) for the U.S. Navy and the U.S. Department of Defense. Located in Northwest Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

, it is one of the pre-1900 astronomical observatories located in an urban area; at the time of its construction, it was far from the light pollution
Light pollution
Light pollution, also known as photopollution or luminous pollution, is excessive or obtrusive artificial light.The International Dark-Sky Association defines light pollution as:...

 thrown off by the (then-smaller) city center. Today, the observatory's primary observational work
Astrometry
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our Galaxy, the Milky...

 is done at the U.S. Navy's higher elevation United States Naval Observatory, Flagstaff Station (NOFS)
United States Naval Observatory Flagstaff Station
The United States Naval Observatory Flagstaff Station , is a scientific astronomical observatory operated as a Navy Echelon V command and the national dark-sky observing Facility/observatory subordinate to the United States Naval Observatory . USNO and NOFS are commands within the CNMOC claimancy,...

 near Flagstaff, Arizona
Flagstaff, Arizona
Flagstaff is a city located in northern Arizona, in the southwestern United States. In 2010, the city's population was 65,870. The population of the Metropolitan Statistical Area was at 134,421 in 2010. It is the county seat of Coconino County...

. USNO also has an "Alternate Master Clock" site in Colorado Springs, CO which, with the "Master Clock
Master clock
A master clock is a precision clock that provides timing signals to synchronize slave clocks as part of a clock network. The master clock in such installations is controlled by an accurate quartz crystal oscillator, usually referenced to an external frequency standard such as MSF, which is part of...

", provides precise time
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...

 to the GPS satellite
GPS satellite
A GPS satellite is a satellite used by the NAVSTAR Global Positioning System . The first satellite in the system, Navstar 1, was launched February 22, 1978. The GPS satellite constellation is operated by the 50th Space Wing of the United States Air Force....

 constellation run by the U.S. Air Force; and it performs radio VLBI-based positions of quasars with numerous global collaborators, in order to produce Earth Orientation parameters
International Earth Rotation and Reference Systems Service
The International Earth Rotation and Reference Systems Service , formerly the International Earth Rotation Service, is the body responsible for maintaining global time and reference frame standards, notably through its Earth Orientation Parameter and International Celestial Reference System ...

. Aside from its scientific mission, since 1974, the Observatory is the official residence of the Vice President of the United States
Vice President of the United States
The Vice President of the United States is the holder of a public office created by the United States Constitution. The Vice President, together with the President of the United States, is indirectly elected by the people, through the Electoral College, to a four-year term...

.

History

Established by the order of the Secretary of the Navy John Branch
John Branch
John Branch, Jr. served as U.S. Senator, Secretary of the Navy, the 19th Governor of the state of North Carolina, and was the sixth and last territorial governor of Florida....

 on 6 December 1830 as the Depot of Charts and Instruments, the Observatory rose from humble beginnings. Placed under the command of Lieutenant Louis M. Goldsborough
Louis M. Goldsborough
Louis Malesherbes Goldsborough was a rear admiral in the United States Navy during the Civil War. He held several sea commands during the Civil War, including the North Atlantic Blockading Squadron...

, with an annual budget of $330, its primary function was the restoration, repair, and rating of navigational instruments. It was made into a national observatory in 1842 via a federal law and a Congressional appropriation of $25,000. Lieutenant James Melville Gilliss
James Melville Gilliss
James Melville Gilliss was an astronomer, United States Navy officer and founder of the United States Naval Observatory.-History:...

 was put in charge of "obtaining the instruments needed and books."

The observatory's primary mission was to care for the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

's marine chronometer
Marine chronometer
A marine chronometer is a clock that is precise and accurate enough to be used as a portable time standard; it can therefore be used to determine longitude by means of celestial navigation...

s, charts, and other navigational equipment. It calibrated ships' chronometers by timing the transit
Astronomical transit
The term transit or astronomical transit has three meanings in astronomy:* A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point...

 of star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...

s across the meridian
Meridian (astronomy)
This article is about the astronomical concept. For other uses of the word, see Meridian.In the sky, a meridian is an imaginary great circle on the celestial sphere. It passes through the north point on the horizon, through the celestial pole, up to the zenith, through the south point on the...

. Initially located downtown
Old Naval Observatory
Old Naval Observatory is a site in Washington, D.C..The observatory operated from 1844 to 1893 when it was closed in favor of a new U.S. Naval Observatory facility on Massachusetts Avenue. The building and grounds were retained by the U.S. Navy, which first used it to house the Naval Museum of...

 at 38.89510°N 77.05145°W in Foggy Bottom
Foggy Bottom
Foggy Bottom is one of the oldest late 18th and 19th-century neighborhoods in Washington, D.C. The area is thought to have received the name because its riverside location made it susceptible to concentrations of fog and industrial smoke, an atmospheric trait that did not prevent the neighborhood...

 (near the Lincoln Memorial
Lincoln Memorial
The Lincoln Memorial is an American memorial built to honor the 16th President of the United States, Abraham Lincoln. It is located on the National Mall in Washington, D.C. The architect was Henry Bacon, the sculptor of the main statue was Daniel Chester French, and the painter of the interior...

), the observatory moved in 1893 to its present location on a 2000-foot circle of land atop Observatory Hill overlooking Massachusetts Avenue.

The first superintendent was Navy Commander Matthew Fontaine Maury
Matthew Fontaine Maury
Matthew Fontaine Maury , United States Navy was an American astronomer, historian, oceanographer, meteorologist, cartographer, author, geologist, and educator....

. Maury had the world's first vulcanized
Vulcanization
Vulcanization or vulcanisation is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent "curatives." These additives modify the polymer by forming crosslinks between individual polymer chains. Vulcanized material is...

 time ball
Time ball
A time ball is a large painted wooden or metal ball that drops at a predetermined time, principally to enable sailors to check their marine chronometers from their boats offshore...

, created to his specifications by Charles Goodyear
Charles Goodyear
Charles Goodyear was an American inventor who developed a process to vulcanize rubber in 1839 -- a method that he perfected while living and working in Springfield, Massachusetts in 1844, and for which he received patent number 3633 from the United States Patent Office on June 15, 1844Although...

 for the U.S. Observatory. It was the first time ball in the United States, being placed into service in 1845, and the 12th in the world. Maury kept accurate time by the stars and planets. The time ball was dropped every day except Sunday precisely at the astronomically defined moment of Mean Solar Noon, enabling all ships and civilians to know the exact time. By the end of the American Civil War, the Observatory's clocks were linked via telegraph to ring the alarm bells in all of the Washington, D.C. firehouses three times a day, and by the early 1870s the Observatory's daily noon time signal was being distributed nationwide via the Western Union
Western Union
The Western Union Company is a financial services and communications company based in the United States. Its North American headquarters is in Englewood, Colorado. Up until 2006, Western Union was the best-known U.S...

 Telegraph Company. Time was also "sold" to the railroads and was used in conjunction with railroad chronometers to schedule American rail transport. Early in the 20th century, the Arlington Time Signal broadcast this service to wireless
Wireless
Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications...

 receivers.

The names "National Observatory" and "Naval Observatory" were both used for 10 years, until a ruling was passed to use only the term "Naval Observatory".

In 1849 the Nautical Almanac Office (NAO) was established in Cambridge, Massachusetts
Cambridge, Massachusetts
Cambridge is a city in Middlesex County, Massachusetts, United States, in the Greater Boston area. It was named in honor of the University of Cambridge in England, an important center of the Puritan theology embraced by the town's founders. Cambridge is home to two of the world's most prominent...

 as a separate organisation. It was moved to Washington, D. C. in 1866, colocating with the U. S. Naval Observatory in 1893. On September 20, 1894, the NAO became a "branch" of USNO, however it remained autonomous for several years after this.

President John Quincy Adams
John Quincy Adams
John Quincy Adams was the sixth President of the United States . He served as an American diplomat, Senator, and Congressional representative. He was a member of the Federalist, Democratic-Republican, National Republican, and later Anti-Masonic and Whig parties. Adams was the son of former...

, who in 1825 signed the bill for the creation of a national observatory just before leaving presidential office, had intended for it to be called the National Observatory. He spent many nights at the observatory with Maury, watching and charting the stars, which had always been one of Adams' avocations.

In November 1913 the Paris Observatory
Paris Observatory
The Paris Observatory is the foremost astronomical observatory of France, and one of the largest astronomical centres in the world...

, using the Eiffel Tower
Eiffel Tower
The Eiffel Tower is a puddle iron lattice tower located on the Champ de Mars in Paris. Built in 1889, it has become both a global icon of France and one of the most recognizable structures in the world...

 as an antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

, exchanged sustained wireless (radio) signals with the United States Naval Observatory, using an antenna in Arlington, Virginia to determine the exact difference of longitude between the two institutions.
In 1934, the last large telescope to be installed at USNO saw "first light". This 40-inch aperture instrument was also the second (and final) telescope made by famed optician, George Ritchey. The Ritchey-Chrétien telescope
Ritchey-Chrétien telescope
A Ritchey–Chrétien telescope is a specialized Cassegrain telescope designed to eliminate coma, thus providing a large field of view compared to a more conventional configuration. An RCT has a hyperbolic primary and a hyperbolic secondary mirror. It was invented in the early 1910s by American...

 design has since become the defacto optical design for nearly all major telescopes, including the famed Keck telescopes
Keck telescopes
The W. M. Keck Observatory is a two-telescope astronomical observatory at an elevation of near the summit of Mauna Kea in Hawai'i. The primary mirrors of each of the two telescopes are in diameter, making them the second largest optical telescopes in the world, slightly behind the Gran Telescopio...

 and the spaceborne Hubble Telescope. Unfortunately, light pollution forced USNO to think of other more viable locations to continue work, and so began a search. The final dark sky site chosen was Flagstaff, Arizona
Flagstaff, Arizona
Flagstaff is a city located in northern Arizona, in the southwestern United States. In 2010, the city's population was 65,870. The population of the Metropolitan Statistical Area was at 134,421 in 2010. It is the county seat of Coconino County...

, and so the 40-inch telescope was moved to that location, beginning operations at the new Navy command, now called the Naval Observatory Flagstaff Station
United States Naval Observatory Flagstaff Station
The United States Naval Observatory Flagstaff Station , is a scientific astronomical observatory operated as a Navy Echelon V command and the national dark-sky observing Facility/observatory subordinate to the United States Naval Observatory . USNO and NOFS are commands within the CNMOC claimancy,...

 (NOFS). Those operations commenced in 1955, and within a decade, the Navy's largest telescope, the 61-inch "Kaj Strand Astrometric Reflector" was built, seeing light at NOFS in 1964.

The modern United States Naval Observatory continues to be a major authority in the areas of precise time and time interval
Precise Time and Time Interval (PTTI)
Precise Time and Time Interval is a Department of Defense Military Standard which details a mechanism and waveform for distributing highly accurate timing information....

, Earth orientation
Earth Orientation Parameters
The Earth's rotation is not even. Any motion in/on the Earth causes a slowdown or speedup of the rotation, or a change of rotation axis. Most of them can be ignored, but movements of very large mass, like sea current or tide can produce discernible changes and cause error to very precise...

, astrometry
Astrometry
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our Galaxy, the Milky...

 and celestial observation. In collaboration with many national and international scientific establishments, it determines the timing and astronomical data required for accurate navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...

, astrometry
Astrometry
Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our Galaxy, the Milky...

, and fundamental astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and calculation methods
Naval Observatory Vector Astrometry Subroutines
The Naval Observatory Vector Astrometry Software is a software library for astrometry-related numerical computations. It is developed by the Astronomical Applications Department, United States Naval Observatory...

—and distributes this information (such as astronomical catalogs) in the Astronomical Almanac
Astronomical Almanac
The Astronomical Almanac is an almanac published by the United States Naval Observatory and Her Majesty's Nautical Almanac Office, containing solar system ephemeris and catalogs of selected stellar and extragalactic objects....

, the Nautical Almanac
Nautical Almanac
Nautical Almanac can refer to:* Nautical almanac - a publication describing the positions and movements of celestial bodies* American Ephemeris and Nautical Almanac - first published in 1852* U.S...

, and on-line.

Perhaps it is best known to the general public for its highly accurate ensemble of atomic clock
Atomic clock
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element...

s and its year 2000 Timeball replacement. The site also houses the largest astronomy library in the United States (and the largest astrophysical periodicals collection in the world). The library includes a large collection of rare, often famous, physics and astronomy books from across the past millennium.

USNO continues to maintain its dark-sky
Dark-sky movement
The dark-sky movement is a campaign by people who want to reduce light pollution so people can see the stars, to reduce the effects of unnatural lighting on the environment, and to cut down on energy usage....

 observatory, NOFS
United States Naval Observatory Flagstaff Station
The United States Naval Observatory Flagstaff Station , is a scientific astronomical observatory operated as a Navy Echelon V command and the national dark-sky observing Facility/observatory subordinate to the United States Naval Observatory . USNO and NOFS are commands within the CNMOC claimancy,...

, near Flagstaff
Flagstaff, Arizona
Flagstaff is a city located in northern Arizona, in the southwestern United States. In 2010, the city's population was 65,870. The population of the Metropolitan Statistical Area was at 134,421 in 2010. It is the county seat of Coconino County...

, Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

, which also now oversees the Navy Prototype Optical Interferometer
Navy Prototype Optical Interferometer
The Navy Prototype Optical Interferometer , is an astronomical interferometer operated by the United States Naval Observatory Flagstaff Station, in collaboration with the Naval Research Laboratory and The Lowell Observatory...

. NOFS opens to the public one weekend annually, in the autumn. The Alternate Master Clock, mentioned above, also continues to operate at Schriever AFB in Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

.

Departments

In 1990, the Orbital Mechanics Department and Astronomical Applications Department were established, and Nautical Almanac Office became a division of the Astronomical Applications Department. The Orbital Mechanics Department operated under P.K. Seidelmann until 1994 when the department was abolished, and its functions were moved to a group within the Astronomical Applications Department.

Official Residence of the Vice President of the United States

Since 1974, and separated from auspices of the Naval Observatory, Number One Observatory Circle
Number One Observatory Circle
Number One Observatory Circle is the official residence of the Vice President of the United States.Located on the northeast grounds of the United States Naval Observatory in Washington, DC, the house was built in 1893 for its superintendent. The Chief of Naval Operations liked the house so much...

, a house situated in the grounds of the observatory (formerly the residence of its superintendent, and later the home of the Chief of Naval Operations
Chief of Naval Operations
The Chief of Naval Operations is a statutory office held by a four-star admiral in the United States Navy, and is the most senior uniformed officer assigned to serve in the Department of the Navy. The office is a military adviser and deputy to the Secretary of the Navy...

), has been the official residence of the Vice President of the United States
Vice President of the United States
The Vice President of the United States is the holder of a public office created by the United States Constitution. The Vice President, together with the President of the United States, is indirectly elected by the people, through the Electoral College, to a four-year term...

.

According to a May 15, 2009 blog posting by Newsweek's
Newsweek
Newsweek is an American weekly news magazine published in New York City. It is distributed throughout the United States and internationally. It is the second-largest news weekly magazine in the U.S., having trailed Time in circulation and advertising revenue for most of its existence...

Eleanor Clift
Eleanor Clift
Eleanor Clift is a political reporter, television pundit and author. She is currently a contributing editor for Newsweek magazine. Her column, "Capitol Letter" is posted each week on the Newsweek and MSNBC websites...

, Vice President Joe Biden
Joe Biden
Joseph Robinette "Joe" Biden, Jr. is the 47th and current Vice President of the United States, serving under President Barack Obama...

 recently revealed the existence of what Clift described as a bunker-like room in the residence. The bunker is the secure, undisclosed location where former Vice President Dick Cheney
Dick Cheney
Richard Bruce "Dick" Cheney served as the 46th Vice President of the United States , under George W. Bush....

 remained under protection in secret after the 9/11 attacks: according to Clift's report, entitled "Shining Light on Cheney's Hideaway"
Biden said a young naval officer giving him a tour of the residence showed him the hideaway, which is behind a massive steel door secured by an elaborate lock with a narrow connecting hallway lined with shelves filled with communications equipment.
Biden's press office subsequently issued a statement denying the bunker report, suggesting that Biden had instead been describing "an upstairs workspace".

Time service

The U.S. Naval Observatory operates two Master Clock facilities. The primary facility, in Washington, D.C. maintains 57 HP
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...

/Agilent/Symmetricom 5071A-001 high performance cesium atomic clocks and 24 hydrogen maser
Hydrogen maser
A Hydrogen maser, also known as hydrogen frequency standard, is a specific type of maser that uses the intrinsic properties of the hydrogen atom to serve as a precision frequency reference....

s. The alternate master clock, at Schriever Air Force Base
Schriever Air Force Base
Schriever Air Force Base is a base of the United States Air Force located approximately 10 miles east of Peterson AFB near Colorado Springs in El Paso County, Colorado, United States.-Overview:...

, maintains 12 cesium clocks and 3 masers. The observatory also operates two rubidium
Rubidium
Rubidium is a chemical element with the symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metallic element of the alkali metal group. Its atomic mass is 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other elements in group 1, such as very rapid...

 atomic fountain
Atomic fountain
An atomic fountain is a cloud of atoms that are tossed upwards by lasers in the Earth's gravitational field. If visible, it would resemble the water in a fountain. While weightless in the toss, the atoms are measured to set the frequency of an atomic clock....

 clocks, which have a stability reaching 7×10−16. The observatory intends to build several more of this type for use at its two facilities.

The U.S. Naval Observatory provides public time service via 26 NTP
Network Time Protocol
The Network Time Protocol is a protocol and software implementation for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. Originally designed by David L...

 servers on the public Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

, and via telephone voice announcements:
  • +1 202 762-1401 (Washington, D.C.)
  • +1 202 762-1069
  • +1 719 567-6742 (Colorado Springs)


The voice of actor Fred Covington (1928–1993) has been announcing the USNO time since 1978.

The voice announcements provide local and universal time
Universal Time
Universal Time is a time scale based on the rotation of the Earth. It is a modern continuation of Greenwich Mean Time , i.e., the mean solar time on the Prime Meridian at Greenwich, and GMT is sometimes used loosely as a synonym for UTC...

 every 15 seconds over a background of once-per-second ticks, with the ticks lengthened to prominent beep twice per 15 seconds after the preceding voice announcement.

The voice announcements always begin with the local time. When calling Washington, silence (only second ticks) may be heard for a few seconds before the next scheduled local time announcement. When calling Colorado, the local time announcement begins at the next 5 second interval, which means that the seconds portion of the times announced depends on the time of the call, and that there is a 1 in 3 chance, as shown in the table, of there being no beep at the top of each minute, which is what most watches and clocks require to synchronize.
USNO telephone time service example, beginning 23:33:00 UTC
Seconds Washington Colorado (1 of 3 possibilities)
:00–:04 Universal time 23 hours, 33 minutes, 5 seconds. Mountain Daylight Time 17 hours, 33 minutes, 5 seconds.
:05–:09 U.S. Naval Observatory Master Clock. At the tone,
Eastern Daylight Time 19 hours, 33 minutes, 15 seconds
Universal time 23 hours, 33 minutes, 10 seconds.
:10–:14 U.S. Naval Observatory Master Clock. At the tone,
Mountain Daylight Time 17 hours, 33 minutes, 20 seconds.
:15–:19 Universal time 23 hours, 33 minutes, 20 seconds.
:20–:24 U.S. Naval Observatory Master Clock. At the tone,
Eastern Daylight Time 19 hours, 33 minutes, 30 seconds.
Universal time 23 hours, 33 minutes, 25 seconds.
:25–:29 U.S. Naval Observatory Master Clock. At the tone,
Mountain Daylight Time 17 hours, 33 minutes, 35 seconds.
:30–:34 Universal time 23 hours, 33 minutes, 35 seconds.
:35–:39 U.S. Naval Observatory Master Clock. At the tone,
Eastern Daylight Time 19 hours, 33 minutes, 45 seconds.
Universal time 23 hours, 33 minutes, 40 seconds.
:40–:44 U.S. Naval Observatory Master Clock. At the tone,
Mountain Daylight Time 17 hours, 33 minutes, 50 seconds.
:45–:49 Universal time 23 hours, 33 minutes, 50 seconds.
:50–:54 U.S. Naval Observatory Master Clock. At the tone,
Eastern Daylight Time 19 hours, 34 minutes, exactly.
Universal time 23 hours, 33 minutes, 55 seconds.
:55–:59 U.S. Naval Observatory Master Clock. At the tone,


The USNO also operates a modem time service, and provides time to the Global Positioning System.

Publications

  • Astronomical Observations made at the U.S. Naval Observatory (USNOA) (v.1-6: 1846-1867)
  • Astronomical and Meteorological Observations made at the U.S. Naval Observatory (USNOM) (v.1-22: 1862-1880)
  • Observations made at the U.S. Naval Observatory (USNOO) (v.1-7: 1887-1893)
  • Publications of the U.S. Naval Observatory, Second Series (PUSNO) (v.1-16: 1900-1949)
  • U.S. Naval Observatory Circulars
  • The Astronomical Almanac
  • The Nautical Almanac
    The Nautical Almanac
    The Nautical Almanac has been the familiar name for a series of official British almanacs published under various titles since the first issue of The Nautical Almanac and Astronomical Ephemeris, for 1767: this was the first nautical almanac ever to contain data dedicated to the convenient...

  • The Air Almanac
  • Astronomical Phenomena

See also

  • List of observatories
  • Navy Prototype Optical Interferometer
    Navy Prototype Optical Interferometer
    The Navy Prototype Optical Interferometer , is an astronomical interferometer operated by the United States Naval Observatory Flagstaff Station, in collaboration with the Naval Research Laboratory and The Lowell Observatory...

  • Rear Admiral Samuel P. Carter
    Samuel P. Carter
    Samuel Perry "Powhatan" Carter was a United States naval officer who served in the Union Army as a brevet major general during the American Civil War and became a rear admiral in the postbellum United States Navy. He was the first and thusfar only United States officer to have been commissioned...

  • United States Naval Observatory Flagstaff Station
    United States Naval Observatory Flagstaff Station
    The United States Naval Observatory Flagstaff Station , is a scientific astronomical observatory operated as a Navy Echelon V command and the national dark-sky observing Facility/observatory subordinate to the United States Naval Observatory . USNO and NOFS are commands within the CNMOC claimancy,...


Further reading

  • Sky and Ocean Joined – The U.S. Naval Observatory 1830-2000 by Steven J. Dick (2003) ISBN 0-521-81599-1

External links





The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK