United States Naval Observatory Flagstaff Station
Encyclopedia
The United States Naval Observatory Flagstaff Station (or NOFS), 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). USNO (itself an Echelon IV command) 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 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 35 scientists (astronomers
and astrophysicists
), optical and mechanical engineers, and support staff. It is currently manned at 20 personnel. 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) and photometry
(defined as brightness
variations
, often in terms of 'color'
) – in the form of million-to-billion-star catalogs for a wide diversity of U.S. global (and spaceborne
) position and navigation
interests. 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 in order to facilitate its production of very accurate/precise astronomical catalog
s, such as USNO-B, NOMAD, and others delivered by NOFS. Astrometry for such catalogs (producing a "celestial reference frame" (CRF), such as the ICRF
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 function
s (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 milli-arcseconds
, to provide an accurate faint—or bright – "background", upon which users may reference their own critical work. 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 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 internal faint-star astrometric reference frame, 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, 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 and spaceborne instrumentation.
The NOFS staff is organized into four divisions: Optical/Infrared
, Engineering & Site Operations
, Digital Catalogs
, and Navy Optical Interferometer(NOI)
Divisions. Additional management staff members serve executive, IT (computer LAN/systems), fiscal, administrative, and facilities functions.
_______________________________________
NOFS is the U.S. Navy's highest-elevation facility, and is 'land-locked', adjacent to Northern Arizona's San Francisco Peaks, on the alpine Colorado Plateau
and geographically above the Mogollon Rim
. The U.S. Navy selected the Flagstaff location to conduct the DoD's astrometric mission, owing to good seeing and dark skies
there. Flagstaff and Coconino County
minimize northern Arizona light pollution
through legislation of progressive code
– which regulates local lighting
. Indeed, despite a half-century-young history, NOFS has a rich heritage which is derived from its parent organization, USNO, the oldest scientific institution in the U.S. At an elevation of approximately 7700 feet, NOFS is home to a number of astronomical instruments (some also described in the worldwide list of optical telescopes):
NOFS operates the Navy Optical Interferometer
(recently the "P" was dropped, to "NOI"), in collaboration with Lowell Observatory
and the Naval Research Laboratory at Anderson Mesa
, 15 miles south-east of Flagstaff. It is a successful example of the venerable Michelson Interferometer
design. The majority of interferometric operations
are funded and managed by NOFS. Lowell Observatory and NRL join in to guide scientific efforts through the NOI Operational Advisory Panel (OAP). NOI is one of the few major instruments globally which can conduct optical interferometry
. See an illustration of its layout, at bottom. NOI has been used to study absolute astrometric positions of stars, binary stars, Be Stars
, Oblate stars
, Rapidly rotating star
, those with starspot
s, and the imaging of stellar disks
(the first in history) and flare stars. In 2007–2008, NOI obtained closure phases of satellites orbiting in geostationary orbit
. In 2009 efforts began to finalize acceptance of four additional 1.8-meter telescopes into the NOI array, which formerly were slated to be a part of the Keck Observatory interferometric array. Under Secretary of the Navy
acceptance occurred in November 2010.
The 1.3 m (51-inch) large-field R-C telescope was initially produced by DFM Engineering
and then corrected and automated by NOFS staff. Corning Glass Works and Kodak made the primary mirror. The hyperbolic secondary has an advanced, computer-controlled collimation (alignment) system in order to permit very precise positions of stars and satellites (milli-arcsecond
astrometry) across its wide field of view. This system analyzes optical aberrations of the optical path, modeled by taking slope fits
of the wavefront
deviations revealed using a Hartmann mask
. The telescope also now sports a state-of-the art, cryogenic wide-field mosaic CCD camera. It will also permit employment of the new "Microcam", an orthogonal transfer array (OTA), with Pan-STARRS
heritage. Other advanced camera systems are also deployed for use on this telescope, such as the LANL-produced RULLI single photon counter, nCam. Using the telescope's special software controls, the telescope can track both stars and man-made satellites orbiting the Earth, while the camera images both. The 1.3m dome itself is compact, owing to the fast overall optics
at f/4. It is located near by and southwest of, the very large 61-inch dome. In addition to astrometric studies (such as for Space Situational Awareness, SDSS
and SST), research on this telescope includes the study of blue
and K-Giant
stars, celestial mechanics
and dynamics of multiple star systems, characterizations of artificial satellites, and the astrometry and transit photometry of exoplanets. Astrometrically, exoplanets also confuse centroid of a parent star's PSF—and there are many exoplanets—so the impact of their not-bland dynamics must be understood.
Congressionally appropriated in 1961, the 61-inch Kaj Strand Telescope (or 1.55-m Kaj Strand Astrometric Reflector, KSAR) remains largest telescope operated by the U.S. Navy since it saw first light in 1964. This status will change when the NOI four 1.8-meter telescopes see their own first light in the near future. KSAR rides in the arms of an equatorial fork mount. The telescope is used in both the visible spectrum
, and in the near infrared (NIR), the latter using a sub-30-Kelvin
, helium-refrigerated, InSb (Indium antimonide) camera, "Astrocam". In 1978, the 1.55-m telescope was used to discover the moon of dwarf planet
Pluto
, named Charon
(Pluto itself was discovered in 1930, across town at Lowell Observatory
). The Charon discovery led to mass calculations which ultimately revealed how tiny Pluto was, and eventually caused the IAU
to reclassify Pluto as a dwarf (not a principle) planet. The 1.55-meter telescope was also used to observe and track NASA's Deep Impact Spacecraft, as it navigated to a successful inter-planetary impact with the celebrated Comet 9p/Tempel, in 2005. This telescope is particularly well-suited to perform stellar parallax
studies, narrow-field astrometry supporting space navigation, and has also played a key role in discovering one of the coolest-ever known Brown Dwarf
objects, in 2002. The 61" dome is centrally located on NOFS grounds, with support and office buildings attached to the dome structures. The large vacuum coating chamber
facility is also located in this complex. The chamber can provide very accurate coatings and overcoatings of 100 (+/-2) Angstrom
thickness (approximately 56 aluminium atoms thick), for small-to-multi-ton optics up to 72-inches (1.82 meters) in diameter, in a vacuum exceeding 7 x 10^6 Torr, using a vertical-optic, 1500-ampere discharge system. A Dielectric coating
capability has also been demonstrated. Large optics and telescope components can be moved about NOFS using its suite of cranes, lifts, cargo elevators and specialized carts. The main complex also contains a controlled-environment, optical and electronics lab for laser, adaptive optics, optics development, collimation, mechanical, and micro-electronic control systems needed for NOFS and NOI.
The KSAR Telescope's 60-foot diameter steel dome is quite large for the telescope's aperture, owing to its telescope's long f/9.8 focal ratio (favorable for very accurate optical collimation, or alignment, needed for astrometric observation). It uses a very wide 2-shutter, vertical slit. Development studies have taken place to successfully show that planned life-cycle replacement of this venerable instrument can be efficiently done within the original dome, for a future telescope with an aperture of up to 3.6-meters, by using fast, modern-day optics.. However, the 61-inch telescope remains unique in its ability to operationally conduct both very high-accuracy relative astrometry to the micro-arcsecond level, and close-separation, PSF photometry
. Several key programs take advantage of this capability to this day.
The 40-inch (1-meter) "Ritchey Telescope" is also an equatorially-driven, fork-mounted telescope. The Ritchey is the original Station telescope which was moved from USNO in Washington in 1955. It is also the first R-C telescope ever made from that famous optical prescription, and was coincidentally the last telescope built by George Ritchey himself. The telescope is still in operation after a half century of astronomy at NOFS. It performs key quasar
-based reference frame
operations, transit detections of exoplanets, Vilnius photometry
, M-Dwarf star
analysis, dynamical system analysis
, reference support to orbiting space object information
, horizontal parallax guide support to NOI
, and it performs photometric operations
support to astrometric studies (along with its newer siblings). The 40-inch also can carry a number of liquid Nitrogen
-cooled cameras, a coronagraph
, and a nine-stellar magnitude neutral density spot focal plane array camera, through which star positions are cross-checked before use in fundamental NOI reference frame astrometry. This telescope is also used to test internally-developed optical adaptive optics
(AO) systems, using tip-tilt
and deformable mirror
optics. The Shack-Hartmann
AO system allows for corrections of the wavefront
's aberrations caused by scintillation (degraded seeing
), to higher Zernike polynomials
. AO systems at NOFS will migrate to the 1.55m and 1.8m telescopes for future incorporation there.
The 40-inch dome is located at the summit and highest point of the modest mountain upon which NOFS is located. It is adjacent to a comprehensive instrumentation shop, which includes sophisticated, CAD-driven
CNC fabrication machinery, and a broad array of design and support tooling.
.
A modern-day example of a fully robotic
transit telescope is the small 0.2m (8 in) Flagstaff Astrometric Scanning Transit Telescope (FASTT) located at the observatory. FASTT provides extremely precise positions of solar system objects for incorporation into the USNO Astronomical Almanac
and Nautical Almanac
. These ephemerides are also used by NASA
in the deep space navigation of its planetary and extra-orbital spacecraft. This telescope is responsible for NASA JPL's successful 2005 navigation-to-landing of the Huygens Lander
on Titan
, a major moon
orbiting Saturn
. FASTT is located 150 yards southwest of the primary complex. Attached to its large "hut" is the building housing NOFS' electronics and electrical engineering laboratories and clean rooms, where most of the advanced camera electronics, cryogenics and telescope control drives are developed and made.
Soon NOFS will add the USNO Robotic Astrometric Telescope (URAT) to its suite of intrumentation. URAT was devised in Washington, DC, from previous instrumentation (the NOFS Twin Astrograph), used the astrograph to produce the catalog, UCAC. URAT will deploy to NOFS by the end of 2011, and three years later to CTIO, for southern hemisphere coverage
(so as to complete four pi-steradians
sky coverage). The URAT system employs a very large, liquid-nitrogen-cooled, CCD chip (10K by 10K), to allow wide-field operations with its 111 megapixel camera (at a pixel size of 9 by 9 microns). URAT's dome is adjacent to the NOFS 40" Ritchey dome.
NOFS telescopes are completely run (usually in a fully automated manner) through the use of a 'commonized', Python
-code-based telescope control system (TCS), which allows astronomers to remotely control and prioritize all telescope operations throughout the observatory's IA-compliant
high-speed computer network LAN
. Owing to the its susceptibility to lightning strikes atop the mountain, all telescopes and IT
systems are also carefully lightning-protected, fully electrically isolated, grounded to an underground earthing network, and protected with lighting arrestors
. All domes are of metal design and grounded, in order to provide Faraday cage
-type lightning protection for the sensitive instrumentation within. While essential to protect from the severe effects caused by lightning, the Faraday caging only partially protects electronics from man-made EMI/RFI
that causes CCD read noise
. Dome/Slit 'focusing' of EMI requires distancing EMI sources from the observatory, as has been done at NOFS. As well, a locally designed, automated weather station can robotically close telescope domes
using its TCS interface, if it detects inclement weather (or even the damaging smoke from possible wildfire
), and protect NOFS telescopes.
_______________________________________
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.
The United States Naval Observatory, Flagstaff Station celebrated its 50th anniversary of the move there from Washington, D.C. in late 2005. Each autumn, NOFS opens its doors annually to the public, during the Flagstaff Festival of Science. In 2009, visitor attendance topped 710.
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).
NOFS remains active in supporting regional dark skies, both to support its national protection mission, and to promote and protect a national resource legacy for generations of humans to come.
Observatory
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geology, oceanography and volcanology are examples of disciplines for which observatories have been constructed...
/observatory subordinate to the United States Naval Observatory
United States Naval Observatory
The United States Naval Observatory is one of the oldest scientific agencies in the United States, with a primary mission to produce Positioning, Navigation, and Timing for the U.S. Navy and the U.S. Department of Defense...
(USNO). USNO (itself an Echelon IV command) and NOFS are commands within the CNMOC
Commander, Naval Meteorology and Oceanography Command
The Naval Meteorology and Oceanography Command serves as the operational arm of the Naval Oceanography Program. Headquartered at the Stennis Space Center in Mississippi, COMNAVMETOCCOM is a third echelon command reporting to United States Fleet Forces Command...
claimancy, the latter which serves the U.S. Navy on meteorological and oceanographic matters in addition to overseeing astronomical
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
ones. The Flagstaff Station 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
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...
in 1955, and has positions
United States civil service
In the United States, the civil service was established in 1872. The Federal Civil Service is defined as "all appointive positions in the executive, judicial, and legislative branches of the Government of the United States, except positions in the uniformed services." . In the early 19th century,...
for 35 scientists (astronomers
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
and astrophysicists
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...
), optical and mechanical engineers, and support staff. It is currently manned at 20 personnel. Its principal mission is to provide the military and others extremely accurate, ground-based 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...
(defined as the positions of celestial
Star position
Star position in the sky is defined by a pair of angles. These two angles - which refer to the celestial equator - are called declination and right ascension ....
and artificial space objects) and photometry
Photometry (astronomy)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation...
(defined as brightness
Surface brightness
The overall brightness of an extended astronomical object such as a galaxy, star cluster, or nebula, can be measured by its total magnitude, integrated magnitude or integrated visual magnitude; a related concept is surface brightness, which specifies the brightness of a standard-sized piece of an...
variations
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
, often in terms of 'color'
Wien's displacement law
Wien's displacement law states that the wavelength distribution of thermal radiation from a black body at any temperature has essentially the same shape as the distribution at any other temperature, except that each wavelength is displaced on the graph...
) – in the form of million-to-billion-star catalogs for a wide diversity of U.S. global (and spaceborne
Space Communications and Navigation Program
The Space Communications and Navigation program places the three prime NASA space communications networks, Space Network , Near Earth Network , and the Deep Space Network , under one Management and Systems Engineering umbrella. It was established in 2006...
) position and navigation
Celestial navigation
Celestial navigation, also known as astronavigation, is a position fixing technique that has evolved over several thousand years to help sailors cross oceans without having to rely on estimated calculations, or dead reckoning, to know their position...
interests. 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 in order to facilitate its production of very accurate/precise astronomical catalog
Astronomical catalog
An astronomical catalog or catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery...
s, such as USNO-B, NOMAD, and others delivered by NOFS. Astrometry for such catalogs (producing a "celestial reference frame" (CRF), such as the ICRF
International Celestial Reference Frame
The International Celestial Reference Frame is a quasi-inertial reference frame centered at the barycenter of the Solar System, defined by the measured positions of 212 extragalactic sources . Although relativity implies that there is no true inertial frame, the extragalactic sources used to...
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 function
Point spread function
The point spread function describes the response of an imaging system to a point source or point object. A more general term for the PSF is a system's impulse response, the PSF being the impulse response of a focused optical system. The PSF in many contexts can be thought of as the extended blob...
s (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
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
/multiple
Multiple star
A multiple star consists of three or more stars which appear from the Earth to be close to one another in the sky. This may result from the stars being physically close and gravitationally bound to each other, in which case it is physical, or this closeness may be merely apparent, in which case...
, flare
Flare star
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to magnetic reconnection in the atmospheres of the stars. The brightness increase is...
, oblate
Gravity darkening
Gravity darkening, also referred to as Gravity Brightening, is an astronomical phenomenon where a star rotates so rapidly that it has a detectably oblate spheroid shape, such as in Regulus in the Leo constellation....
, starspot
Starspot
Starspots are equivalent to sunspots but located on other stars. Spots the size of sunspots are very hard to detect since they are too small to cause fluctuations in brightness...
-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 milli-arcseconds
Minute of arc
A minute of arc, arcminute, or minute of angle , is a unit of angular measurement equal to one sixtieth of one degree. In turn, a second of arc or arcsecond is one sixtieth of one minute of arc....
, to provide an accurate faint—or bright – "background", upon which users may reference their own critical work. 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
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
. 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 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
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...
movements (such as precession
Precession
Precession is a change in the orientation of the rotation axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle is constant...
, nutation
Nutation
Nutation is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behavior of a mechanism...
, parallax
Stellar parallax
Stellar parallax is the effect of parallax on distant stars in astronomy. It is parallax on an interstellar scale, and it can be used to determine the distance of Earth to another star directly with accurate astrometry...
, geophysical and tidal
Earth tide
Earth tide is the sub-meter motion of the Earth of about 12 hours or longer caused by Moon and Sun gravitation, also called body tide which is the largest contribution globally. The largest body tide contribution is from the semidiurnal constituents, but there are also significant diurnal...
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
Epoch (astronomy)
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as celestial coordinates, or elliptical orbital elements of a celestial body, where these are subject to perturbations and vary with time...
. One remedy to break such a daunting cycle is to maintain an ongoing input and updating process, which makes the common operational picture
Common Operational Picture
A common operational picture is a single identical display of relevant information shared by more than one Command...
(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 internal faint-star astrometric reference frame, 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
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
, NRL
United States Naval Research Laboratory
The United States Naval Research Laboratory is the corporate research laboratory for the United States Navy and the United States Marine Corps and conducts a program of scientific research and development. NRL opened in 1923 at the instigation of Thomas Edison...
, MIT, NRAO, Smithsonian, GEODSS, Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
(LANL), AMOS
Air Force Maui Optical and Supercomputing observatory
The Air Force Maui Optical and Supercomputing observatory is an Air Force Research Laboratory operating location on Maui with a twofold mission. First, it conducts the research and development mission on the Maui Space Surveillance System at the Maui Space Surveillance Complex...
, USNA
USNA
USNA may refer to:* United States Naval Academy* United States of North America. A fictional country including the modern USA as well as Canada in the 1985 computer game A Mind Forever Voyaging...
, Air Force Space Command
Air Force Space Command
Air Force Space Command is a major command of the United States Department of the Air Force, with its headquarters at Peterson Air Force Base, Colorado. AFSPC supports U.S. military operations worldwide through the use of many different types of satellite, launch and cyber operations....
, Lowell Observatory
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965....
, NOAO, AAS
American Astronomical Society
The American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...
, IAU
IAU
IAU may refer to:*International Astronomical Union*International American University*International American University College of Medicine*International Association of Universities*International Association of Ultrarunners...
, and many other academic and DoD
United States Department of Defense
The United States Department of Defense is the U.S...
institutions. Staff Astronomers observe both on local telescopes and at other observatories around the globe—using both terrestrial and spaceborne instrumentation.
The NOFS staff is organized into four divisions: Optical/Infrared
Infrared astronomy
Infrared astronomy is the branch of astronomy and astrophysics that studies astronomical objects visible in infrared radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers...
, Engineering & Site Operations
Optical engineering
Optical engineering is the field of study that focuses on applications of optics. Optical engineers design components of optical instruments such as lenses, microscopes, telescopes, and other equipment that utilizes the properties of light. Other devices include optical sensors and measurement...
, Digital Catalogs
Star catalogue
A star catalogue, or star catalog, is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some...
, and Navy Optical Interferometer(NOI)
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...
Divisions. Additional management staff members serve executive, IT (computer LAN/systems), fiscal, administrative, and facilities functions.
_______________________________________
NOFS is the U.S. Navy's highest-elevation facility, and is 'land-locked', adjacent to Northern Arizona's San Francisco Peaks, on the alpine Colorado Plateau
Colorado Plateau
The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...
and geographically above the Mogollon Rim
Mogollon Rim
The Mogollon Rim is a topographical and geological feature running across the U.S. state of Arizona. It extends approximately from northern Yavapai County eastward to near the border with New Mexico.-Description:...
. The U.S. Navy selected the Flagstaff location to conduct the DoD's astrometric mission, owing to good seeing and dark skies
Bortle Dark-Sky Scale
The Bortle Dark-Sky Scale is a nine-level numeric scale that measures the night sky's and stars' brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution and skyglow. John E...
there. Flagstaff and Coconino County
Coconino County, Arizona
-2010:Whereas according to the 2010 U.S. Census Bureau:*61.7% White*1.2% Black*27.3% Native American*1.4% Asian*0.1% Native Hawaiian or Pacific Islander*3.1% Two or more races*5.2% Other races*13.5% Hispanic or Latino -2000:...
minimize northern Arizona 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:...
through legislation of progressive code
Building code
A building code, or building control, is a set of rules that specify the minimum acceptable level of safety for constructed objects such as buildings and nonbuilding structures. The main purpose of building codes are to protect public health, safety and general welfare as they relate to the...
– which regulates local lighting
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:...
. Indeed, despite a half-century-young history, NOFS has a rich heritage which is derived from its parent organization, USNO, the oldest scientific institution in the U.S. At an elevation of approximately 7700 feet, NOFS is home to a number of astronomical instruments (some also described in the worldwide list of optical telescopes):
NOFS operates the Navy 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...
(recently the "P" was dropped, to "NOI"), in collaboration with Lowell Observatory
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965....
and the Naval Research Laboratory at Anderson Mesa
Anderson Mesa
Lowell Observatory, Anderson Mesa Station, USA, was established in 1959 as a dark-sky observing site for Lowell Observatory. Anderson Mesa is now home to several large reflecting telescopes that are used for observing programs such as LONEOS...
, 15 miles south-east of Flagstaff. It is a successful example of the venerable Michelson Interferometer
Michelson interferometer
The Michelson interferometer is the most common configuration for optical interferometry and was invented by Albert Abraham Michelson. An interference pattern is produced by splitting a beam of light into two paths, bouncing the beams back and recombining them...
design. The majority of interferometric operations
Astronomical optical interferometry
One of the first astronomical interferometers was built on the Mount Wilson Observatory's reflector telescope in 1920 in order to measure the diameters of stars. The red giant star Betelgeuse was among the first to have its diameter determined in this way...
are funded and managed by NOFS. Lowell Observatory and NRL join in to guide scientific efforts through the NOI Operational Advisory Panel (OAP). NOI is one of the few major instruments globally which can conduct optical interferometry
Astronomical optical interferometry
One of the first astronomical interferometers was built on the Mount Wilson Observatory's reflector telescope in 1920 in order to measure the diameters of stars. The red giant star Betelgeuse was among the first to have its diameter determined in this way...
. See an illustration of its layout, at bottom. NOI has been used to study absolute astrometric positions of stars, binary stars, Be Stars
Be star
A Be star is a B-type star with prominent emission lines of hydrogen in its spectrum. The designation is combined by the spectral class, B, and the lowercase e denoting emission in the spectral classification system. Line emission from other atomic ions might be present as well, but is typically...
, Oblate stars
Gravity darkening
Gravity darkening, also referred to as Gravity Brightening, is an astronomical phenomenon where a star rotates so rapidly that it has a detectably oblate spheroid shape, such as in Regulus in the Leo constellation....
, Rapidly rotating star
Stellar rotation
Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface....
, those with starspot
Starspot
Starspots are equivalent to sunspots but located on other stars. Spots the size of sunspots are very hard to detect since they are too small to cause fluctuations in brightness...
s, and the imaging of stellar disks
Limb darkening
Limb darkening refers to the diminishing of intensity in the image of a star as one moves from the center of the image to the edge or "limb" of the image...
(the first in history) and flare stars. In 2007–2008, NOI obtained closure phases of satellites orbiting in geostationary orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...
. In 2009 efforts began to finalize acceptance of four additional 1.8-meter telescopes into the NOI array, which formerly were slated to be a part of the Keck Observatory interferometric array. Under Secretary of the Navy
Under Secretary of the Navy
The Under Secretary of the Navy is the second-highest ranking civilian official in the United States Department of the Navy. The Under Secretary, called the "Under" in Pentagon slang, reports to the Secretary of the Navy ....
acceptance occurred in November 2010.
The 1.3 m (51-inch) large-field R-C telescope was initially produced by DFM Engineering
DFM Engineering
DFM Engineering is an American telescope and optics manufacturer. DFM Engineering was founded in 1979 by Dr. Frank Melsheimer. DFM makes medium size Cassegrain telescopes and their associated systems including telescope optics, control systems, and mounts. A range of pre-designed telescopes are...
and then corrected and automated by NOFS staff. Corning Glass Works and Kodak made the primary mirror. The hyperbolic secondary has an advanced, computer-controlled collimation (alignment) system in order to permit very precise positions of stars and satellites (milli-arcsecond
Angular resolution
Angular resolution, or spatial resolution, describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object...
astrometry) across its wide field of view. This system analyzes optical aberrations of the optical path, modeled by taking slope fits
Curve fitting
Curve fitting is the process of constructing a curve, or mathematical function, that has the best fit to a series of data points, possibly subject to constraints. Curve fitting can involve either interpolation, where an exact fit to the data is required, or smoothing, in which a "smooth" function...
of the wavefront
Wavefront
In physics, a wavefront is the locus of points having the same phase. Since infrared, optical, x-ray and gamma-ray frequencies are so high, the temporal component of electromagnetic waves is usually ignored at these wavelengths, and it is only the phase of the spatial oscillation that is described...
deviations revealed using a Hartmann mask
Hartmann mask
Hartmann mask is a tool to help focusing telescopes, mainly used by amateur astronomers.- Theory and practice :...
. The telescope also now sports a state-of-the art, cryogenic wide-field mosaic CCD camera. It will also permit employment of the new "Microcam", an orthogonal transfer array (OTA), with Pan-STARRS
Pan-STARRS
The Panoramic Survey Telescope and Rapid Response System is a planned array of astronomical cameras and telescopes and computing facility that will survey the sky on a continual basis, including accurate astrometry and photometry of detected objects...
heritage. Other advanced camera systems are also deployed for use on this telescope, such as the LANL-produced RULLI single photon counter, nCam. Using the telescope's special software controls, the telescope can track both stars and man-made satellites orbiting the Earth, while the camera images both. The 1.3m dome itself is compact, owing to the fast overall optics
Lens speed
Lens speed refers to the maximum aperture diameter, or minimum f-number, of a photographic lens. A lens with a larger maximum aperture is a fast lens because it delivers more light intensity to the focal plane, allowing a faster shutter speed...
at f/4. It is located near by and southwest of, the very large 61-inch dome. In addition to astrometric studies (such as for Space Situational Awareness, SDSS
Sloan Digital Sky Survey
The Sloan Digital Sky Survey or SDSS is a major multi-filter imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project was named after the Alfred P...
and SST), research on this telescope includes the study of blue
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
and K-Giant
Giant star
A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...
stars, celestial mechanics
Celestial mechanics
Celestial mechanics is the branch of astronomy that deals with the motions of celestial objects. The field applies principles of physics, historically classical mechanics, to astronomical objects such as stars and planets to produce ephemeris data. Orbital mechanics is a subfield which focuses on...
and dynamics of multiple star systems, characterizations of artificial satellites, and the astrometry and transit photometry of exoplanets. Astrometrically, exoplanets also confuse centroid of a parent star's PSF—and there are many exoplanets—so the impact of their not-bland dynamics must be understood.
Congressionally appropriated in 1961, the 61-inch Kaj Strand Telescope (or 1.55-m Kaj Strand Astrometric Reflector, KSAR) remains largest telescope operated by the U.S. Navy since it saw first light in 1964. This status will change when the NOI four 1.8-meter telescopes see their own first light in the near future. KSAR rides in the arms of an equatorial fork mount. The telescope is used in both the visible spectrum
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
, and in the near infrared (NIR), the latter using a sub-30-Kelvin
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
, helium-refrigerated, InSb (Indium antimonide) camera, "Astrocam". In 1978, the 1.55-m telescope was used to discover the moon of dwarf planet
Dwarf planet
A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite...
Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...
, named Charon
Charon (moon)
Charon is the largest satellite of the dwarf planet Pluto. It was discovered in 1978 at the United States Naval Observatory Flagstaff Station. Following the 2005 discovery of two other natural satellites of Pluto , Charon may also be referred to as Pluto I...
(Pluto itself was discovered in 1930, across town at Lowell Observatory
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965....
). The Charon discovery led to mass calculations which ultimately revealed how tiny Pluto was, and eventually caused the IAU
IAU
IAU may refer to:*International Astronomical Union*International American University*International American University College of Medicine*International Association of Universities*International Association of Ultrarunners...
to reclassify Pluto as a dwarf (not a principle) planet. The 1.55-meter telescope was also used to observe and track NASA's Deep Impact Spacecraft, as it navigated to a successful inter-planetary impact with the celebrated Comet 9p/Tempel, in 2005. This telescope is particularly well-suited to perform stellar parallax
Stellar parallax
Stellar parallax is the effect of parallax on distant stars in astronomy. It is parallax on an interstellar scale, and it can be used to determine the distance of Earth to another star directly with accurate astrometry...
studies, narrow-field astrometry supporting space navigation, and has also played a key role in discovering one of the coolest-ever known Brown Dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...
objects, in 2002. The 61" dome is centrally located on NOFS grounds, with support and office buildings attached to the dome structures. The large vacuum coating chamber
Vacuum deposition
Vacuum deposition is a family of processes used to deposit layers atom-by-atom or molecule-by-molecule at sub-atmospheric pressure on a solid surface. The layers may be as thin as one atom to millimeters thick . There may be multiple layers of different materials...
facility is also located in this complex. The chamber can provide very accurate coatings and overcoatings of 100 (+/-2) Angstrom
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
thickness (approximately 56 aluminium atoms thick), for small-to-multi-ton optics up to 72-inches (1.82 meters) in diameter, in a vacuum exceeding 7 x 10^6 Torr, using a vertical-optic, 1500-ampere discharge system. A Dielectric coating
Dielectric mirror
A dielectric mirror is a type of a mirror composed of multiple thin layers of dielectric material, typically deposited on a substrate of glass or some other optical material. By careful choice of the type and thickness of the dielectric layers, one can design an optical coating with specified...
capability has also been demonstrated. Large optics and telescope components can be moved about NOFS using its suite of cranes, lifts, cargo elevators and specialized carts. The main complex also contains a controlled-environment, optical and electronics lab for laser, adaptive optics, optics development, collimation, mechanical, and micro-electronic control systems needed for NOFS and NOI.
The KSAR Telescope's 60-foot diameter steel dome is quite large for the telescope's aperture, owing to its telescope's long f/9.8 focal ratio (favorable for very accurate optical collimation, or alignment, needed for astrometric observation). It uses a very wide 2-shutter, vertical slit. Development studies have taken place to successfully show that planned life-cycle replacement of this venerable instrument can be efficiently done within the original dome, for a future telescope with an aperture of up to 3.6-meters, by using fast, modern-day optics.. However, the 61-inch telescope remains unique in its ability to operationally conduct both very high-accuracy relative astrometry to the micro-arcsecond level, and close-separation, PSF photometry
Photometry (astronomy)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation...
. Several key programs take advantage of this capability to this day.
The 40-inch (1-meter) "Ritchey Telescope" is also an equatorially-driven, fork-mounted telescope. The Ritchey is the original Station telescope which was moved from USNO in Washington in 1955. It is also the first R-C telescope ever made from that famous optical prescription, and was coincidentally the last telescope built by George Ritchey himself. The telescope is still in operation after a half century of astronomy at NOFS. It performs key quasar
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
-based reference frame
International Celestial Reference Frame
The International Celestial Reference Frame is a quasi-inertial reference frame centered at the barycenter of the Solar System, defined by the measured positions of 212 extragalactic sources . Although relativity implies that there is no true inertial frame, the extragalactic sources used to...
operations, transit detections of exoplanets, Vilnius photometry
Vilnius photometric system
The Vilnius photometric system is a medium-band seven-colour photometric system , created in 1963 by Vytautas Straižys and his coworkers. This system was highly optimized for classification of stars from ground based observations...
, M-Dwarf star
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
analysis, dynamical system analysis
Celestial mechanics
Celestial mechanics is the branch of astronomy that deals with the motions of celestial objects. The field applies principles of physics, historically classical mechanics, to astronomical objects such as stars and planets to produce ephemeris data. Orbital mechanics is a subfield which focuses on...
, reference support to orbiting space object information
United States Space Surveillance Network
The United States Space Surveillance Network is a critical part of United States Strategic Command's mission and involves detecting, tracking, cataloging and identifying artificial objects orbiting Earth, i.e. active/inactive satellites, spent rocket bodies, or fragmentation debris...
, horizontal parallax guide support to NOI
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...
, and it performs photometric operations
Photometry (astronomy)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation...
support to astrometric studies (along with its newer siblings). The 40-inch also can carry a number of liquid Nitrogen
Liquid nitrogen
Liquid nitrogen is nitrogen in a liquid state at a very low temperature. It is produced industrially by fractional distillation of liquid air. Liquid nitrogen is a colourless clear liquid with density of 0.807 g/mL at its boiling point and a dielectric constant of 1.4...
-cooled cameras, a coronagraph
Coronagraph
A coronagraph is a telescopic attachment designed to block out the direct light from a star so that nearby objects – which otherwise would be hidden in the star's bright glare – can be resolved...
, and a nine-stellar magnitude neutral density spot focal plane array camera, through which star positions are cross-checked before use in fundamental NOI reference frame astrometry. This telescope is also used to test internally-developed optical adaptive optics
Adaptive optics
Adaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...
(AO) systems, using tip-tilt
Tilt (optics)
In optics, tilt is a deviation in the direction a beam of light propagates. Tilt quantifies the average slope in both the X and Y directions of a wavefront or phase profile across the pupil of an optical system...
and deformable mirror
Deformable mirror
Deformable mirror represents the most convenient tool for wavefront control and correction of optical aberrations. Deformable mirrors are used in combination with wavefront sensors and real-time control systems in adaptive optics...
optics. The Shack-Hartmann
Shack-Hartmann
A Shack–Hartmann wavefront sensor is an optical instrument used to characterize an imaging system. It is a wavefront sensor commonly used in adaptive optics systems. It consists of an array of lenses of the same focal length. Each is focused onto a photon sensor...
AO system allows for corrections of the wavefront
Wavefront
In physics, a wavefront is the locus of points having the same phase. Since infrared, optical, x-ray and gamma-ray frequencies are so high, the temporal component of electromagnetic waves is usually ignored at these wavelengths, and it is only the phase of the spatial oscillation that is described...
's aberrations caused by scintillation (degraded seeing
Astronomical seeing
Astronomical seeing refers to the blurring and twinkling of astronomical objects such as stars caused by turbulent mixing in the Earth's atmosphere varying the optical refractive index...
), to higher Zernike polynomials
Zernike polynomials
In mathematics, the Zernike polynomials are a sequence of polynomials that are orthogonal on the unit disk. Named after Frits Zernike, they play an important role in beam optics.-Definitions:There are even and odd Zernike polynomials...
. AO systems at NOFS will migrate to the 1.55m and 1.8m telescopes for future incorporation there.
The 40-inch dome is located at the summit and highest point of the modest mountain upon which NOFS is located. It is adjacent to a comprehensive instrumentation shop, which includes sophisticated, CAD-driven
Computer-aided design
Computer-aided design , also known as computer-aided design and drafting , is the use of computer technology for the process of design and design-documentation. Computer Aided Drafting describes the process of drafting with a computer...
CNC fabrication machinery, and a broad array of design and support tooling.
.
A modern-day example of a fully robotic
Robotic telescope
A robotic telescope is an astronomical telescope and detector system that makes observations without the intervention of a human. In astronomical disciplines, a telescope qualifies as robotic if it makes those observations without being operated by a human, even if a human has to initiate the...
transit telescope is the small 0.2m (8 in) Flagstaff Astrometric Scanning Transit Telescope (FASTT) located at the observatory. FASTT provides extremely precise positions of solar system objects for incorporation into the USNO 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....
and 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...
. These ephemerides are also used by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
in the deep space navigation of its planetary and extra-orbital spacecraft. This telescope is responsible for NASA JPL's successful 2005 navigation-to-landing of the Huygens Lander
Cassini-Huygens
Cassini–Huygens is a joint NASA/ESA/ASI spacecraft mission studying the planet Saturn and its many natural satellites since 2004. Launched in 1997 after nearly two decades of gestation, it includes a Saturn orbiter and an atmospheric probe/lander for the moon Titan, although it has also returned...
on Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
, a major moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
orbiting Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
. FASTT is located 150 yards southwest of the primary complex. Attached to its large "hut" is the building housing NOFS' electronics and electrical engineering laboratories and clean rooms, where most of the advanced camera electronics, cryogenics and telescope control drives are developed and made.
Soon NOFS will add the USNO Robotic Astrometric Telescope (URAT) to its suite of intrumentation. URAT was devised in Washington, DC, from previous instrumentation (the NOFS Twin Astrograph), used the astrograph to produce the catalog, UCAC. URAT will deploy to NOFS by the end of 2011, and three years later to CTIO, for southern hemisphere coverage
Celestial sphere
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. Projected upward from Earth's equator and poles are the...
(so as to complete four pi-steradians
Solid angle
The solid angle, Ω, is the two-dimensional angle in three-dimensional space that an object subtends at a point. It is a measure of how large that object appears to an observer looking from that point...
sky coverage). The URAT system employs a very large, liquid-nitrogen-cooled, CCD chip (10K by 10K), to allow wide-field operations with its 111 megapixel camera (at a pixel size of 9 by 9 microns). URAT's dome is adjacent to the NOFS 40" Ritchey dome.
NOFS telescopes are completely run (usually in a fully automated manner) through the use of a 'commonized', Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
-code-based telescope control system (TCS), which allows astronomers to remotely control and prioritize all telescope operations throughout the observatory's IA-compliant
Information Assurance
Information assurance is the practice of managing risks related to the use, processing, storage, and transmission of information or data and the systems and processes used for those purposes...
high-speed computer network LAN
Län
Län and lääni refer to the administrative divisions used in Sweden and previously in Finland. The provinces of Finland were abolished on January 1, 2010....
. Owing to the its susceptibility to lightning strikes atop the mountain, all telescopes and IT
Information technology
Information technology is the acquisition, processing, storage and dissemination of vocal, pictorial, textual and numerical information by a microelectronics-based combination of computing and telecommunications...
systems are also carefully lightning-protected, fully electrically isolated, grounded to an underground earthing network, and protected with lighting arrestors
Lightning rod
A lightning rod or lightning conductor is a metal rod or conductor mounted on top of a building and electrically connected to the ground through a wire, to protect the building in the event of lightning...
. All domes are of metal design and grounded, in order to provide Faraday cage
Faraday cage
A Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks out external static and non-static electric fields...
-type lightning protection for the sensitive instrumentation within. While essential to protect from the severe effects caused by lightning, the Faraday caging only partially protects electronics from man-made EMI/RFI
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
that causes CCD read noise
Image noise
Image noise is random variation of brightness or color information in images, and is usually an aspect of electronic noise. It can be produced by the sensor and circuitry of a scanner or digital camera...
. Dome/Slit 'focusing' of EMI requires distancing EMI sources from the observatory, as has been done at NOFS. As well, a locally designed, automated weather station can robotically close telescope domes
Robotic telescope
A robotic telescope is an astronomical telescope and detector system that makes observations without the intervention of a human. In astronomical disciplines, a telescope qualifies as robotic if it makes those observations without being operated by a human, even if a human has to initiate the...
using its TCS interface, if it detects inclement weather (or even the damaging smoke from possible wildfire
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
), and protect NOFS telescopes.
_______________________________________
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)
National Executive Committee for Space-Based Positioning, Navigation and Timing
The National Executive Committee for Space-Based Positioning, Navigation and Timing is a United States Government organisation which advises and coordinates federal departments and agencies on matters concerning the Global Positioning System, space navigation, navigational references, and related...
mission.
The United States Naval Observatory, Flagstaff Station celebrated its 50th anniversary of the move there from Washington, D.C. in late 2005. Each autumn, NOFS opens its doors annually to the public, during the Flagstaff Festival of Science. In 2009, visitor attendance topped 710.
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).
NOFS remains active in supporting regional dark skies, both to support its national protection mission, and to promote and protect a national resource legacy for generations of humans to come.