United States Naval Observatory The United States Naval Observatory ( USNO ) is one of the oldest scientific agencies in the United States , 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 . , 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 thrown off by the ( then - smaller ) city center . Today , the observatory ' s primary observational work is done at the U . S . Navy ' s higher elevation United States Naval Observatory Flagstaff Station ( NOFS ) near Flagstaff , Arizona . USNO also has an " Alternate Master Clock " site in Colorado Springs , Colorado which , with the " Master Clock " , provides precise time to the GPS satellite 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 . Aside from its scientific mission , since 1974 , the Observatory is the official residence of the Vice President of the United States . History . Established by the order of the 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 , 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 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 chronometer s , charts , and other navigational equipment . It calibrate d ships ' chronometers by timing the transit of stars across the meridian . Initially located downtown at in Foggy Bottom ( near the Lincoln Memorial ) , 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 . 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 , 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 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 receivers . The names " National Observatory " and " Naval Observatory " were both used for 10 years , until a ruling was passed to officially use the latter . The precedent to have been ascribed the title ' national observatory ' can in part be attributed to the efforts of John Quincy Adams during that period , who made protracted efforts to bring astronomy to a national level at that time . In 1849 the Nautical Almanac Office ( NAO ) 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 . 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 . He spent many nights at the observatory with Maury , watching and charting the stars , which had always been one of Adams ' avocations . 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 heavily on photographic methods , the naval observers returned 350 photographic plate s in 1874 , and 1 , 380 measurable plates in 1882 . The results of the surveys conducted simultaneously from several locations around the world ( for each of the two transits ) 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 , with a probable error of 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 ( 66 cm ) refractor ( a telescope with a lens ) , then located at Foggy Bottom . In 1893 it was moved to the present location , into the 21st century . In November 1913 the Paris Observatory , using the Eiffel Tower as an antenna , 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 design has since become the defacto optical design for nearly all major telescopes , including the famed Keck telescopes 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 , 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 ( 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 , Earth orientation , astrometry and celestial observation . In collaboration with many national and international scientific establishments , it determines the timing and astronomical data required for accurate navigation , astrometry , and fundamental astronomy and calculation methods — and distributes this information ( such as astronomical catalogs ) in the Astronomical Almanac , the Nautical Almanac , and on - line . Perhaps it is best known to the general public for its highly accurate ensemble of atomic clock 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 observatory , NOFS , near Flagstaff , Arizona , which also now oversees the Navy Precision Optical Interferometer . 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 . 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 . In 2010 , USNO ' s astronomical ' department ' known as the Naval Observatory Flagstaff Station was officially made autonomous as an Echelon Five command separate from USNO , but reporting to it . In the 7000 - plus foot alpine woodlands adjacent to Flagstaff , Arizona , USNO performs its national , Celestial Reference Frame ( CRF ) mission under dark skies unique to that region . Official Residence of the Vice President of the United States . Since 1974 , and separated from auspices of the Naval Observatory , Number One Observatory Circle , a house situated in the grounds of the observatory , which was formerly the residence of its superintendent , and later the home of the Chief of Naval Operations , has been the official residence of the Vice President of the United States . According to a May 15 , 2009 blog posting by " Newsweek ' s " Eleanor Clift , Vice President Joe Biden 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 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 / Agilent / Symmetricom 5071A - 001 high performance cesium atomic clocks and 24 hydrogen maser s . The alternate master clock , at Schriever Air Force Base , maintains 12 cesium clocks and 3 masers . The observatory also operates two rubidium atomic fountain clocks , which have a stability reaching 7×10 . 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 servers on the public Internet , and via telephone voice announcements : The voice of actor Fred Covington ( 1928 – 1993 ) has been announcing the USNO time since 1978 . The voice announcements provide local and universal time 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 . The USNO also operates a modem time service , and provides time to the Global Positioning System . External links . Category : United States Naval Observatory