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The United States Naval Observatory Flagstaff Station (NOFS), is an astronomical observatory near Flagstaff, Arizona, USA. It is the national dark-sky observing facility for the U.S. Department of Defense, under the United States Naval Observatory (USNO).〔() 〕 NOFS and USNO combine as the Celestial Reference Frame〔() 〕 manager for the U.S. Secretary of Defense.〔() 〕〔(【引用サイトリンク】title=U.S. Naval Observatory roles and missions in the application of astrometric principles toward Space Situational Awareness )〕 The Director of NOFS (an Echelon Five Naval command and installation) is also identified as Commander, Task Force Element 80.7.3.1 under the CNMOC operational infrastructure.〔Naval Radio Message originated from COMNAVMETOCCOM STENNIS SPACE CENTER MS, with date-Time Group R 201600Z OCT 14〕 ==General information== The USNO and NOFS are commands within the CNMOC claimancy, the latter which serves the U.S. Navy on meteorological and oceanographic matters in addition to overseeing astronomical ones. The Flagstaff Station〔(Tour and Visiting Information for USNO Flagstaff Station – Naval Oceanography Portal ). Usno.navy.mil. Retrieved 18 October 2011.〕 is a command which was established by USNO (due to a century of eventually untenable light encroachment in Washington, D.C.) at a site five miles west of Flagstaff, Arizona in 1955, and has positions for primarily operational scientists (astronomers and astrophysicists), optical and mechanical engineers, and support staff. It is currently manned with a core of civil service personnel, supported by defense and astronomical contractors. Its principal mission is to provide the military and others extremely accurate, ground-based astrometry〔() 〕 (defined as the positions of celestial and artificial space objects), Celestial mechanics (dynamical motions of celestial objects) and photometry (defined as brightness variations, often in terms of 'color') – in the form of extremely rigorous million-to-billion-star catalogs for a wide diversity of U.S. global (and spaceborne) position and navigation interests.〔(USNO Flagstaff Station Mission Statement ). Nofs.navy.mil. Retrieved 18 October 2011.〕 NOFS specializes in extremely faint-magnitude, extremely accurate observations which cannot normally be obtained from space telescopes, and remains the most respected astrometric〔 observatory in the world. NOFS remains the senior U.S. Navy facility/unit in the state of Arizona. NOFS science supports every aspect of protection-oriented operations to some level, providing national support and beyond. Work at NOFS covers the gamut of astrometry and astrophysics〔(Naval Observatory Flagstaff Az – Storming Media ). Stormingmedia.us. Retrieved 18 October 2011.〕〔(USNO Preprint Library ). Ad.usno.navy.mil (5 October 2011). Retrieved 18 October 2011.〕 in order to facilitate its production of very accurate/precise astronomical catalogs,〔() 〕 such as USNO-B,〔 〕 NOMAD,〔() 〕 UBAD (USNO Bright-Star Astrometric Database), UNAC (USNO NPOI Astrometric Catalog), ITAU (Infrared Two-Micron Astrometric Update), USNO-Zoetic, and others delivered by NOFS. Astrometry for such catalogs (producing a "celestial reference frame"〔() 〕 (CRF), such as the ICRF〔(ICRS Narrative ). Aa.usno.navy.mil. Retrieved 18 October 2011.〕 is), requires handling terabytes of diverse data on a billion or more celestial objects, all the while accurately characterizing the centroids of the point spread functions (PSFs) of ''each object'' in that vast database, including pinning down positions of innumerable, diverse types of objects. Such diversity severely complicates how to dynamically determine where many of the large collections of celestial objects really 'are'. Complete catalogs require much study of binary/multiple, flare, oblate, starspot-laden stars, and astrometrically extended objects, in addition to the classically 'simple', spheroidally shaped single stars. Many of these types of "problem stars" (and their oddly shaped cousins) proliferate much of the night sky, so must have some accounting, in large major catalogs. Characterizing the astrophysical diversity, so as to know the objects' positions, helps to determine how up to a billion positions can be made accurate to perhaps to a few, critical milliarcseconds, to provide an accurate faint—or bright – "background", upon which users may reference their own critical work. Ultimately catalogs will have requirements for microarcsecond levels of accuracy (a microarcsecond is an angle smaller than the thickness of hair on a six foot man seen from Earth to be standing on the Moon). As well, users may need a large collection of just the brighter magnitude stars, or the much fainter ones (much more difficult to assess), or both. Users may also require a catalog suited to blue or red optical, near or far (or thermal) infrared,〔() 〕 or millimeter/microwave/radio portions of the electromagnetic spectrum. This matches the user's need for a background similar to their observational interests. In astrometry, the PSFs of the stars' centroids vary significantly from one bandpass to another, so must be atoned for in catalog development. Faint star densities are almost exponentially more numerous in a given patch of sky, so faint catalogs will require much more effort to produce for the user. Also, owing to the celestial dynamics (and relativistic effects〔() 〕) of the huge number of such moving objects across their own treks through space, the time expanse required to pin down each set of celestial locations and motions for a perhaps billion-star catalog, can be quite long. Multiple observations of each object may themselves take weeks, months or years, by themselves. This, multiplied by the large number of cataloged objects that must then be reduced for use, and which must be analyzed after observation for a very careful statistical understanding of all catalog errors, forces the rigorous production of most extremely precise and faint astrometric catalogs to take many years, sometimes decades, to complete. Because stars move, both due to their own wanderings (proper motions) throughout space, and due to the observer's Earth orientation movements (such as precession, nutation, parallax, geophysical and tidal variations),〔() 〕 a catalog's accuracy slowly but progressively degrades in increased error over time, beginning the moment after the sky is imaged for cataloging. The degrading motions 'confuse' observations with motions which astrometrists are usually not able to completely constrain despite extensive scientific modeling and deliberation. So eventually a whole new catalog must be produced when a user's needs for given accuracies force a new, updated catalog, for some later epoch. One remedy to break such a daunting cycle is to maintain an ongoing input and updating process, which makes the ''common operational picture'' (COP) produced by such a dynamic catalog, a more efficient and timely means to delver such large quantities of changing data to the variety of users. NOFS has a key program (awaiting funding) called the ''Dynamic Astrometric Database (DyAD)'' which will operate under the near real-time ("''on-the-fly''") paradigm. While principally responsible for the Navy/DoD faint-star astrometric reference frame (and components of its bright-star counterpart), NOFS scientists also externally develop an improved understanding of celestial goings-on, by participating on many science teams and in relevant collaborations. Institutions NOFS works with include DARPA, NASA, NRL, MIT (such as Lincoln Laboratory), Draper Laboratory, NRAO, Smithsonian, GEODSS, Los Alamos National Laboratory (LANL), AMOS, USNA, Air Force Space Command, Lowell Observatory, NOAO, AAS, IAU, and many other academic and DoD institutions. Staff Astronomers observe both on local telescopes and at other observatories around the globe—using both terrestrial, interferometric and spaceborne instrumentation. The NOFS staff is organized into five divisions: (1) Optical/Infrared Astrometry, Remote Sensing & Analysis, (2) Engineering & Site Operations, (3) Digital Catalogs & Astrometric Methods, (4) Navy Precision Optical Interferometer(NPOI), and the (5) Computers and Information Assurance Divisions. Additional management staff members serve executive, fiscal, administrative, and facilities functions. NOFS also serves as the contingency facility ("back-up") for its Washington counterpart's Earth Orientation Parameters and Astronomical Applications production centers.〔() 〕〔() 〕 . NOFS is the U.S. Navy's ''National Dark Sky Site'', and is responsible for the bulk of the 'astrometric component' of the U.S. DoD and national Position-Navigation-Time (PNT) mission.〔(National Executive Committee for Space-Based Positioning, Navigation, and Timing ). Pnt.gov (11 October 2011). Retrieved 18 October 2011.〕 The United States Naval Observatory, Flagstaff Station celebrated its ''50th anniversary'' of the move there from Washington, D.C. in late 2005.〔(Naval Observatory Flagstaff Station Celebrates First Half Century | SpaceRef – Your Space Reference ). SpaceRef (30 September 2005). Retrieved 18 October 2011.〕 Each autumn, NOFS opens its doors annually to the public, during the Flagstaff Festival of Science.〔(Flagstaff Festival of Science 2011 ). Scifest.org. Retrieved 18 October 2011.〕 In 2009, visitor attendance topped 710.〔(– Ever wonder who makes your GPS work? ). Azdailysun.com (27 September 2009). Retrieved 18 October 2011.〕 Dr. John Hall, Director of the Naval Observatory's Equatorial Division from 1947, founded NOFS. Dr. Art Hoag became its first director in 1955 (until 1965); both later were to also become directors of nearby Lowell Observatory.〔()〕 Subsequent directors at NOFS include (in order): 2nd – Dr. Gerald Kron (1965–1973); 3rd – Dr. Harold Ables (1974–1995); 4th – Dr. Conard Dahn (1996–2003); 5th – Dr. Jeff Pier (2003–2008); and 6th – Dr. Paul Shankland (2008–present).〔(【引用サイトリンク】title=Paul Shankland, Ph.D., Director )〕〔(Sky and Ocean Joined – Cambridge University Press ). Cambridge.org. Retrieved 18 October 2011.〕 NOFS remains active in supporting regional ''dark skies'',〔(Christian B. Luginbuhl's Homepage ). Nofs.navy.mil (11 April 2011). Retrieved 18 October 2011.〕〔http://azdailysun.com/news/local/govt-and-politics/news-analysis-dark-skies-helps-seal---vote-in/article_19a371de-7e76-11e3-a0a5-001a4bcf887a.html〕 both to support its national protection mission,〔〔(The USNO's Mission – Naval Oceanography Portal ). Usno.navy.mil. Retrieved 18 October 2011.〕 and to promote and protect a national resource legacy for generations of humans to come.〔(Flagstaff Dark Skies Coalition ). Flagstaffdarkskies.org (7 September 2011). Retrieved 18 October 2011.〕〔(Flag marks 50 years of dark skies ). Azdailysun.com (14 April 2008). Retrieved 18 October 2011.〕〔(IDAHome ). Darksky.org. Retrieved 18 October 2011.〕 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「United States Naval Observatory Flagstaff Station」の詳細全文を読む スポンサード リンク
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