The United States Naval Observatory is one of the oldest scientific agencies in the United States, with a primary mission to produce Positioning and Timing for the United States Navy and the United States Department of Defense. Located in Northwest Washington, D. C. at the Northwestern end of Embassy Row, it is one of the pre-1900 astronomical observatories located in an urban area. Former USNO director Gernot M. R. Winkler initiated the "Master Clock" service that the USNO still operates, which provides precise time to the GPS satellite constellation run by the United States Air Force; the USNO performs radio VLBI-based positions of quasars with numerous global collaborators, in order to produce Earth Orientation parameters. Aside from its scientific mission, a house located within the Naval Observatory complex serves as the official residence of the Vice President of the United States. President John Quincy Adams, 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.

The names "National Observatory" and "Naval Observatory" were both used for 10 years, until a ruling was passed to use the latter. Adams had made protracted efforts to bring astronomy to a national level at that time, he spent many nights at the observatory and charting the stars, which had always been one of Adams' avocations. Established by the order of the United States Secretary of the Navy John Branch 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, with an annual budget of $330, its primary function was the restoration 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 was put in charge of "obtaining the instruments needed and books." Lt. Gilliss visited the principal observatories of Europe with the mission to purchase telescopes and scientific devices and books.

The observatory's primary mission was to care for the United States Navy's marine chronometers and other navigational equipment. It calibrated ships' chronometers by timing the transit of stars across the meridian. Opened in 1844 in Foggy Bottom north of the present site of the Lincoln Memorial and west of the White House, the observatory moved in 1893 to its present location on a 2000-foot circle of land atop Observatory Hill overlooking Massachusetts Avenue; these facilities were listed on the National Register of Historic Places in 2017. The first superintendent was Navy Commander Matthew Fontaine Maury. Maury had the world's first vulcanized time ball, created to his specifications by Charles Goodyear for the U. S. Observatory, it was the first time ball in the United States, being placed into service in 1845, the 12th in the world. Maury kept accurate time by the planets; the time ball was dropped every day except Sunday 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, by the early 1870s the Observatory's daily noon-time signal was being distributed nationwide via the Western Union Telegraph Company. Time was "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 receivers. In 1849 the Nautical Almanac Office was established in Cambridge, Massachusetts as a separate organization, 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. An early scientific duty assigned to the Observatory was the U. S. contribution to the definition of the Astronomical Unit, or the AU, which defines a standard mean distance between the Sun and the Earth, conducted under the auspices of the Congressionally funded U.

S. Transit of Venus Commission; the astronomical measurements taken of the transit of Venus by a number of countries since 1639 resulted in a progressively more accurate definition of the AU. Relying on photographic methods, the naval observers returned 350 photographic plates in 1874, 1,380 measurable plates in 1882; the results of the surveys conducted from several locations around the world produced a final value of the solar parallax, after adjustments, of 8.809", with a probable error of 0.0059", yielding a U. S. defined Earth-Sun distance of 92,797,000 miles, with a probable error of 59,700 miles. This calculated distance was a significant improvement over several previous estimates; the telescope used for the discovery of the Moons of Mars was the 26-inch refractor located at Foggy Bottom. In 1893 it was moved to the present location. In November 1913 the Paris Observatory, using the Eiffel Tower as an antenna, exchanged sustained wireless 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 the second telescope made by famed optician

The Dictionary of Art Historians is an online encyclopedia of topics relating to art historians, art critics and their dictionaries. The mission of the project is to provide free, English-language information on published art historians; the DAH was started in 1986 as a notecard project indexing art historians by the editors Lee R. Sorensen and Monique Daniels. In 2002 the project was migrated to the internet, in 2010 it was adopted by the art history department of Duke University. In 2017, the DAH was adopted by the Wired! Lab at Duke University and a new version of the site was launched in 2018; the project enjoys collaboration with the Journal of Art Historiography, which started in 2010. Starting as a database of art historians mentioned in major art historiographies, the site has grown through the comments and contributions of various authors specializing in national fields of art history. Official website

It Should've Happened a Long Time Ago is an album by Paul Motian on the ECM label. It was released in 1985 and features performances by Motian with Bill Frisell and Joe Lovano and is the first album to feature the trio following three albums where they formed the basis of a quintet; the Allmusic review by Thom Jurek awarded the album 4½ stars, stating: "This is one of the finest recordings that came from ECM in the'80s. Paul Bley led another, which featured Frisell -- as well as John Surman; this set is made of the kind of music that made Manfred Eicher's ECM such a force to be reckoned with. It placed three musicians in a context, comfortable enough to make them want to sing to one another." "It Should've Happened a Long Time Ago" - 6:06 "Fiasco" - 7:49 "Conception Vessel" - 4:31 "Introduction" - 3:05 "India" - 7:26 "In the Year of the Dragon" - 5:56 "Two Women from Padua" - 5:13All compositions by Paul Motian Paul Motian - drums Bill Frisell - guitar Joe Lovano - tenor saxophone