359 Sentences With "astrometry" | Random Sentence Generator

"Gaia is at the forefront of astrometry, charting the sky at precisions that have never been achieved before," said Giménez.

"The star is named in honor of the great American astronomer Edward Emerson Barnard, who was a pioneer of stellar photography and astrometry," Butler said.

Lindegren's publications include more than 90 refereed papers on astrometry, reference frames, data processing, spectroscopy and instrument design. Besides those in space astrometry, a frequently cited paper deals with solar physics and the role of convection on the line profile,The fundamental definition of radial velocity and another considers in a very general way the atmospheric limitations on small-field astrometry.Atmospheric limitations of narrow-field optical astrometry He is a co-author of the canonical paper on the IAU 2000 `Resolutions for Astrometry, Celestial Mechanics, and Metrology in the Relativistic Framework'.The IAU 2000 Resolutions for Astrometry, Celestial Mechanics, and Metrology in the Relativistic Framework: Explanatory Supplement Crucially, the bulk of his contributions to space astrometry has been in the form of a series of unpublished technical notes for Hipparcos and Gaia, amounting to some 200 documents totalling around 3000 pages.

The Naval Observatory Vector Astrometry Software (NOVAS) is a software library for astrometry-related numerical computations. It is developed by the Astronomical Applications Department, United States Naval Observatory. Currently, NOVAS has three different editions for C, Fortran, and Python, respectively.

Primary work consists of planetary, deep sky, NEO studies, astrometry, photometry and astrophotography. IAU/MPC assignment number pending.

It is the last star in the Hipparcos catalogue, HIP 118322, from the Hipparcos (1989–1993) astrometry satellite.

Its variability was discovered from Hipparcos astrometry and it was entered into the General Catalogue of Variable Stars in 1999.

Most are investigated by detailed complex astronomical theories using celestial mechanics using precise positional observations of celestial objects via astrometry.

Stellar photometry was performed in a manner that would systematically reject galaxies. Astrometry was determined using the AGK3, SAOC or CPC catalog stars depending on plate declination. Although the relative astrometry (required for HST) is about 0.3 arc seconds, there are known systematic errors near the plate edges of 1 to 2 arc seconds.

This technology made astrometry less expensive, opening the field to an amateur audience. In 1989, the European Space Agency's Hipparcos satellite took astrometry into orbit, where it could be less affected by mechanical forces of the Earth and optical distortions from its atmosphere. Operated from 1989 to 1993, Hipparcos measured large and small angles on the sky with much greater precision than any previous optical telescopes.

It is instrumental for keeping time, in that UTC is essentially the atomic time synchronized to Earth's rotation by means of exact astronomical observations. Astrometry is an important step in the cosmic distance ladder because it establishes parallax distance estimates for stars in the Milky Way. Astrometry has also been used to support claims of extrasolar planet detection by measuring the displacement the proposed planets cause in their parent star's apparent position on the sky, due to their mutual orbit around the center of mass of the system. Astrometry is more accurate in space missions that are not affected by the distorting effects of the Earth's atmosphere.

They succeeded and the WRO is now code W22. With this code, students are able to submit astrometry data to the Minor Planet Center with ease.

Nicole Capitaine (born Nicole Taton on March 14, 1948) is an astronomer at the Paris Observatory who is known as an expert on astrometry and related standards.

The main belt asteroid 10969 Perryman has been named in recognition of his contributions to astrometry. In 1999 Perryman was awarded the Academy Medal by the Royal Netherlands Academy of Arts and Sciences. In 2011 he was awarded the Tycho Brahe Prize of the European Astronomical Society for his crucial role in the fostering of high precision, global stellar astrometry from space, in particular the development of the Hipparcos mission.

Only newly developed methods of observation using CCD and the highly precise star positions of the astrometry satellite Hipparcos made further improvement possible in the measurement of distance.

The mass of Hiiaka is estimated to be using precise relative astrometry from Hubble Telescope and Keck Telescope and applying 3-body, point-mass model to the Haumean system.

Today Lund Observatory research activity focuses on observational and theoretical astrophysics. Areas covered include galaxy formation and evolution, exoplanet research, laboratory astrophysics, high- energy astrophysics, star clusters, and astrometry (Hipparcos and Gaia).

HD 47536 b is an extrasolar planet located approximately 400 light-years away. Its inclination and thereby true mass is being calculated via astrometry with Hubble. The astrometricians expect publication by mid-2009.

In the 1960s astronomer Peter van de Kamp claimed that he had discovered a planet orbiting Barnard's Star using astrometry. Two papers from 1973 were most influential in discrediting this claim. The first, by John L.Hershey, identified systematic errors in the telescope that van de Kamp had used. The second paper was authored by Gatewood and Heinrich Eichhorn, who repeated the astrometry measurements made by van de Kamp with improved equipment and failed to detect any sign of Barnard's Star companions.

The algorithms used by NOVAS are based on vector astrometry theories and the IAU resolutions. Instead of using trigonometric formulae from spherical astrometry, NOVAS uses the matrix and vector formulation which is more rigorous. This version implements the resolutions on astronomical reference systems and Earth rotation models passed at the IAU General Assemblies in 1997, 2000, and 2006. According to the Astronomical Applications Department, the algorithms used in NOVAS are identical to those used in the production of the US part of the Astronomical Almanac.

Research employs photometry and astrometry of asteroids and comets using the main telescope of Skalnaté Pleso observatory. Furthermore, fish-eye cameras are used to detect bolides on the sky. The head of the department is Ján Svoreň.

She worked on equipping the SAI Observatory on the Lenin Hills with modern equipment. She is the author of the Russian astronomy textbook "Photographic astrometry". A crater on the planet Venus is named Bugoslavskaya in her honour.

He wrote a paper on `Photoelectric astrometry',Photoelectric astrometry: a comparison of methods for precise image location a subject I had proposed, where he systematically discussed the performance of methods for precise image location from observations. It remains a classical paper. The second paper to mention is about the rigidity of the celestial coordinate system obtained by the one-dimensional observations in a scanning satellite as TYCHO/Option A/Hipparcos. The question was asked in 1976 as mentioned above, but it took years before we had the answer which was affirmative.

TAU spacecraft, a 1980s era study which would have used an interstellar precursor probe to expand the baseline for calculating stellar parallax in support of Astrometry The history of astrometry is linked to the history of star catalogues, which gave astronomers reference points for objects in the sky so they could track their movements. This can be dated back to Hipparchus, who around 190 BC used the catalogue of his predecessors Timocharis and Aristillus to discover Earth's precession. In doing so, he also developed the brightness scale still in use today.Walter, Hans G. (2000).

Benjamin Boss (January 9, 1880 - October 17, 1970) was an American astronomer. He served as the director of both the Dudley Observatory in Schenectady, New York and the Department of Meridian Astrometry of the Carnegie Institution of Washington.

Since 2008, the telescope has been used for Very-long-baseline interferometry for both astronomy and geodesy. It is part of the European VLBI Network, the Global mm VLBI Array, and the International VLBI Service for Geodesy and Astrometry.

This minor planet was named after American astronomer Donald Keith Yeomans, a celestial mechanician at JPL and astrometry-expert of the International Halley Watch. The official naming citation was published by the Minor Planet Center on 18 September 1986 ().

This minor planet was named after the astronomical branch astrometry, that precisely measures the positions and movements of astronomical objects including small Solar System bodies. The official naming citation was published by the Minor Planet Center on 4 August 2001 ().

Henden has also positioned himself as a specialist in photometry by writing one of the classic texts in the subject: Astronomical Photometry (1978: Willman-Bell) Henden has worked extensively with amateurs interested in variable stars and minor planet astrometry mainly through the AAVSO.

Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

However, they have proven useful for making very high precision measurements of simple stellar parameters such as size and position (astrometry) and for imaging the nearest giant stars. For details of individual instruments, see the list of astronomical interferometers at visible and infrared wavelengths.

Wulff-Dieter Heintz (3 June 1930 – 10 June 2006) was a German astronomer who worked the latter part of his career in the United States. He was Professor Emeritus of Astronomy at Swarthmore College. He specialised in the characterisation of binary stars using astrometry.

One which he discovered is named after his parents, Elfriede and Erwin Schwab.Kleinplaneten-Namen, Starkenburg Observatory, 28 June 2010, retrieved 13 August 2010. Schwab has discovered asteroids at Starkenburg, Tzec MaunAsteroid Astrometry and Reporting , Tzec Maun Observatory wiki. as well as at the Taunus Observatory.

Astrographs used in astrometry record images that are then used to "map" the positions of objects over a large area of the sky. These maps are then published in catalogs to be used in further study or to serve as reference points for deep-space imaging.

Kaj Aage Gunnar Strand (27 February 1907 - 31 October 2000) was a Danish astronomer who worked in Denmark and the United States. He was Scientific Director of the U.S. Naval Observatory from 1963 to 1977. He specialized in astrometry, especially work on double stars and stellar distances.

Malena Rice and Gregory Laughlin have proposed that a network of telescopes be built to detect occultations by Jupiter Trojans. The timing of these occultations would provide precise astrometry of these objects enabling their orbits to be monitored for variations due to the tide from Planet Nine.

RAVE data is available from the RAVE web server or from the VizieR catalog. The RAVE 4th Data Release, includes the radial velocities, stellar parameters (temperatures, gravities, metallicities), individual abundances and photometric parallaxes/distances as well as supplementary photometry and astrometry for roughly 500 000 stars.

The Gaia DR1 parallax, derived from the combination of the first year of Gaia measurements with Tycho astrometry, is 0.40 ± 0.22 mas. The Gaia team recommend that a further 0.3 mas systematic error is allowed for (i.e. added to the formal margin of error). Smith et al.

The Origins Space Telescope would perform astrometry and astrophysics in the mid- to far- infrared range using a telescope with an aperture of 9.1 m (concept 1) or 5.9 m (concept 2).Origins Space Telescope. Cooray, Asantha R. and the Origins Space Telescope Study Team. American Astronomical Society, AAS Meeting #229.

This minor planet was named in honour of Vladimir Grigorevich Shaposhnikov (1905–1942), who worked at the Simeiz Observatory and was an expert in astrometry, before he was killed on the Eastern Front during the Second World War. The official was published by the Minor Planet Center on 20 February 1976 ().

Ellen Dorrit Hoffleit (March 12, 1907 - April 9, 2007) was an American senior research astronomer at Yale University. She is most widely known for her work in variable stars, astrometry, spectroscopy, meteors, and the Bright Star Catalog, as well as her mentorship of many young women and generations of astronomers.

The Doridis refractor was extensively used for observations of planets, comets, and the moon, as well as for astrometry and photometry of variable stars. In 2014, thanks to a generous donation from Cosmote, the telescope was fully restored and it is used for the purposes of education and public outreach.

Responsible for command and management of the Naval Oceanography Program, utilizing meteorology and oceanography, GI&S;, and precise time and astrometry, to leverage the environment to enable successful strategic, tactical and operational battle space utilization across the continuum of campaigning and at all levels of war – strategic, operational and tactical.

25000 Astrometria, provisional designation ', is a dark background asteroid from the outer regions of the asteroid belt, approximately 20 kilometers in diameter. It was discovered on 28 July 1998, by American astronomer Paul Comba at his Prescott Observatory in Arizona, United States. The asteroid was named in honor of the astronomical branch astrometry.

Modern spectroscopic analyses find an iron content about a factor of 250 lower than that of the Sun. It is one of the closest metal-poor (Population II) stars to Earth. The star was already known by 1912 when W. S. Adams measured its astrometry using a spectrograph in the Mount Wilson Observatory.

Further study of the system using Hubble Space Telescope astrometry revised the mass of HD 38529 c downwards to 17.7 Jupiter masses and suggested the presence of an additional planet, orbiting in the gap between HD 38529 b and c. The possible third planet was refuted after additional radial velocity measurements were collected.

In addition, investigations in astrometry have also been performed. The scientific work of the Central Institute for Astrophysics suffered strongly from the isolation of the GDR from the western world. It was very difficult to come into contact with western colleagues. After the autumn 1989 fall of the Berlin Wall, new possibilities at once arose.

Sextants for astronomical observations were devices depicting a sixth of a circle, used primarily for measuring the positions of stars. They are of significant historical importance, but have been replaced over time by transit telescopes, astrometry techniques, and satellites such as Hipparcos. There are two types of astronomical sextants, mural instruments and frame-based instruments.

Very long baseline interferometry astrometry of PSR B1257+12, a pulsar with a planetary system In PSR J1719-1438, the planet most likely is the companion, or what's left of it after being almost entirely blasted away by the extreme irradiation from the nearby pulsar. PSR B1620-26 b is most likely a captured planet.

Theta Eridani (θ Eridani, abbreviated Theta Eri, θ Eri) is a binary system in the constellation of Eridanus. Its two components are designated θ¹ Eridani, formally named Acamar (the traditional name of the system), and θ² Eridani. The system's distance from the Sun as measured by the Hipparcos astrometry satellite is approximately 120 light-years.

The light-year is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist and popular science publications. The unit most commonly used in professional astrometry is the parsec (symbol: pc, about 3.26 light-years; the distance at which one astronomical unit subtends an angle of one second of arc).

Mizar, also designated Zeta Ursae Majoris (ζ Ursae Majoris, abbreviated Zeta UMa, ζ UMa), is itself a quadruple system and Alcor, also designated 80 Ursae Majoris (80 UMa), is a binary, the pair together forming a sextuple system. The whole system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite.

This minor planet was named in memory of Paul Bourgeois (1898–1974), director of the discovering observatory at Uccle, professor at the Free University of Brussels, credited discoverer of asteroid 1547 Nele, author of various publications in astrometry, astrophysics, meridian astronomy and stellar statistics. The official was published by the Minor Planet Center on 20 February 1976 ().

Since each star has its own independent motion, all constellations will change slowly over time. After tens to hundreds of thousands of years, familiar outlines will become unrecognizable. Astronomers can predict the past or future constellation outlines by measuring individual stars' common proper motions or cpm by accurate astrometry and their radial velocities by astronomical spectroscopy.

A filar micrometer attached to a telescope A filar micrometer is a specialized eyepiece used in astronomical telescopes for astrometry measurements, in microscopes for specimen measurements, and in alignment and surveying telescopes for measuring angles and distances on nearby objects. The word filar derives . It refers to the fine threads or wires used in the device.

The orbit has been derived from astrometry as well as through spectral observations, although that has been difficult because of the high projected rotational velocity. It is also fairly eccentric, at 0.558. Both stars in the system are red dwarfs. The primary component of the system is only 23.7% as massive as the Sun, so it is fully convective.

On 4 August 2020 astronomers announced the discovery of a Saturn-like planet TVLM 513b around this star with a period of days, a mass of between 0.35−0.42 , a circular orbit (e≃0), a semi-major axis of between 0.28−0.31 AU and an inclination angle of 71−88∘. The companion was detected by the radio astrometry method.

A notable member of this group is VB 10, discovered in 1944. This star was the least massive and dimmest star known at the time of its discovery. Based on a discovery claim made in 2009, VB 10 would have become the first star to have an extrasolar planet detected using astrometry, however this clam was later refuted.

This minor planet was named in honor of American astronomer Brian Skiff, discoverer more than 50 asteroids. He significantly contributed to Lowell's asteroid astrometry program, including the rediscovery of the 800-meter potentially hazardous object 69230 Hermes, a long-lost asteroid. The official naming citation was published by the Minor Planet Center on 8 April 1982 ().

The database used to construct this catalog was later transferred from Lick Observatory to the United States Naval Observatory, where it became the basis for the Washington Double Star Catalog.The Washington Double Star Catalog , Brian D. Mason, Gary L. Wycoff, and William I. Hartkopf, astrometry department, United States Naval Observatory; accessed on line July 22, 2008.

In 1997, he became the first Timken University Professor at the university. Shapiro's research interests include astrophysics, astrometry, geophysics, gravitation, including the use of gravitational lenses to assess the age of the universe. In 1981, Edward Bowell discovered the 3832 main belt asteroid and it was later named after Shapiro by his former student Steven J. Ostro.

Gotha Observatory (Seeberg Observatory, Sternwarte Gotha or Seeberg- Sternwarte) was a German astronomical observatory located on Seeberg hill near Gotha, Thuringia, Germany. - see page A29. Initially the observatory was dedicated to astrometry, geodetic and meteorological observation and tracking the time. The minor planet 1346 Gotha was named after the city of Gotha in recognition of the observatory.

By measuring the velocities of pulsars, it is possible to put a limit on the asymmetry of supernova explosions. Also, astrometric results are used to determine the distribution of dark matter in the galaxy. Astronomers use astrometric techniques for the tracking of near-Earth objects. Astrometry is responsible for the detection of many record-breaking Solar System objects.

Currently the most precise distance estimate of 2MASS 0937+2931 is trigonometric parallax, published in 2009 by Schilbach et al.: 163.39 ± 1.76 mas, corresponding to a distance 6.12 ± 0.07 pc, or 19.96 ± 0.22 ly. A less precise parallax of this object, measured under U.S. Naval Observatory Infrared Astrometry Program, was published in 2004 by Vrba et al.

Sarah Lee Lippincott (October 26, 1920 – February 28, 2019), also known as Sarah Lee Lippincott Zimmerman, was an American astronomer. She was professor emerita of astronomy at Swarthmore College and director emerita of the college's Sproul Observatory. She was a pioneer in the use of astrometry to determine the character of binary stars and search for extrasolar planets.

Georg Friedrich Julius Arthur von Auwers (September 12, 1838 – January 24, 1915) was a German astronomer. Auwers was born in Göttingen to Gottfried Daniel Auwers and Emma Christiane Sophie (née Borkenstein). He attended the University of Göttingen and worked at the University of Königsberg. He specialized in astrometry, making very precise measurements of stellar positions and motions.

"Introduction and Growth of the WDS", The Washington Double Star Catalog , Brian D. Mason, Gary L. Wycoff, and William I. Hartkopf, Astrometry Department, United States Naval Observatory, accessed on line August 20, 2008.Sixth Catalog of Orbits of Visual Binary Stars , William I. Hartkopf and Brian D. Mason, United States Naval Observatory, accessed on line August 20, 2008.

In astrometry, the moving-cluster method and the closely related convergent point method are means, primarily of historical interest, for determining the distance to star clusters. They were used on several nearby clusters in the first half of the 1900s to determine distance. The moving-cluster method is now largely superseded by other, usually more accurate distance measures.

Sigma Sagittarii (σ Sagittarii, abbreviated Sigma Sgr, σ Sgr), formally named Nunki , is the second-brightest star in the constellation of Sagittarius. It has an apparent magnitude of +2.05, making it readily visible to the naked eye. The distance to this star, determined using parallax measurements from the Hipparcos astrometry satellite, yields an estimated value of from the Sun.

Those shifts are very large in comparison to the measurement precisions that are required for astrometry. Thus, the BCRS defines its center of coordinates as the center of mass of the entire Solar System, its barycenter. This stable point for gravity helps to minimize relativistic effects from any observational frames of reference within the Solar System.

In her letter to professor Sergey Blazhko, head of the Astrometry Department of Moscow State University, dated 19 October 1942, she wrote that her first bomb she promised the Nazis would be in revenge for the bombing of the Faculty of mechanics and mathematics in the winter. She wrote that she was defending the honor of the university.

High Speed Photometer Instrument Handbook v 3.0. STSci. HST's guidance system can also be used as a scientific instrument. Its three Fine Guidance Sensors (FGS) are primarily used to keep the telescope accurately pointed during an observation, but can also be used to carry out extremely accurate astrometry; measurements accurate to within 0.0003 arcseconds have been achieved.

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 United States Naval Observatory no longer obtains significant astrometric observations, but it 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 star 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 clocks and its year 2000 time ball replacement.

Alcor is a binary star system in the constellation of Ursa Major. It is the fainter companion of Mizar, the two stars forming a naked eye double in the handle of the Big Dipper (or Plough) asterism in the constellation of Ursa Major. The two both lie about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite.

Methods used to determine the true mass of a planet include measuring the distance and period of one of its satellites, advanced astrometry techniques that use the motions of other planets in the same star system, combining radial velocity techniques with transit observations (which indicate very low orbital inclinations), and combining radial velocity techniques with stellar parallax measurements (which also determine orbital inclinations).

Reginald Lawson Waterfield (12 April 1900 – 10 June 1986 in Woolston) was a British hematologist known for his work in amateur astronomy. In particular astrometry and the photographing of comets. He served as Director of the British Astronomical Association Mars Section from 1931-1942 and its president from 1954–1956. After World War II he had to use a wheelchair due to polio.

The low inclination of HD 53680 B's orbit reduces the amplitude of the radial velocity variation that it caused on HD 53680 A. In this case, the effect reduced the minimum mass of the companion into the brown dwarf regime as deduced from observations with the CORALIE spectrograph. The spectroscopic orbit produces far stronger constraint compared to the astrometry-only orbit.

However, in 2016, further analysis or radial velocity data confirmed the presence of an outer planet larger and more eccentric than was originally believed. With high eccentricity and a high mass ratio between the two planets, the system is quite unique. The planet c is also a potential target for GAIA astrometry or atmospheric characterization using direct imaging or high-resolution spectroscopy.

The early civilizations in recorded history made methodical observations of the night sky. These include the Babylonians, Greeks, Indians, Egyptians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars. Nowadays, professional astronomy is often said to be the same as astrophysics.

The International VLBI Service for Geodesy and Astrometry (IVS) is an international collaboration whose purpose is to use the observation of astronomical radio sources using (VLBI) to precisely determine earth orientation parameters (EOP) and celestial reference frames (CRF) and terrestrial reference frames (TRF). IVS is a service operating under the International Astronomical Union (IAU) and the International Association of Geodesy (IAG).

The astrometric core solution for the Gaia mission: overview of models, algorithms, and software implementation This Astrometric Global Iterative Solution (AGIS) is now fully operational within the Gaia Data Processing and Analysis Consortium (DPAC). Lindegren was a member of the ESA Gaia Science Advisory Group before mission selection, and the Gaia Science Team since selection in 2000.Gaia People of the ESA's web site for the Gaia scientific community Within the Gaia Data Processing and Analysis Consortium (DPAC), Lindegren leads the scientific implementation of the Astrometric Global Iterative Solution, a core element in the astrometric processing of the Gaia data. Between 2006–2010 he was project coordinator for the Marie Curie Research Training Network ELSA (European Leadership in Space Astrometry), aiming to develop the science of space astrometry and train the next generation of researchers in this area.

It is spinning rapidly with a projected rotational velocity of 220 km/s, which is giving it a pronounced equatorial bulge that is 25% larger than the polar radius. Analysis of Hipparcos and Gaia astrometry suggests that the relatively large margins of error in the calculated parallax may be due to orbital motion caused by an unseen companion. The companion would be an object orbiting at about .

Directed panspermia can be motivated by biotic ethics that value the basic patterns of organic gene/protein life with its unique complexity and unity, and its drive for self-propagation. Directed panspermia is becoming possible due to developments in solar sails, precise astrometry, the discovery of extrasolar planets, extremophiles and microbial genetic engineering. Cosmological projections suggest that life in space can then have a future.

The NOVAS library can be linked by programs that work with positions of celestial bodies. For example, "Pocket Stars", an astronomy software for Smartphone and PDA platforms, used the NOVAS as its astrometry engine. The Python edition allows calling the NOVAS functions from Python. It is mostly feature complete with respect to the C edition, with a few exceptions, and shares the C edition's API.

In 1958 Strand accepted a position as head of the Astrometry and Astrophysics Division at the U.S. Naval Observatory rising to the position of Scientific Director in 1963. He pioneered in the determination of stellar distances using reflecting telescopes, and was primarily responsible for the design and construction of the Strand Astrometric Telescope, dedicated in 1964 at the United States Naval Observatory Flagstaff Station in Arizona.

This minor planet was named in honor of Russian–American astronomer Alexander Vyssotsky (1888–1973), who joined the faculty of the University of Virginia in 1923 and stayed at the McCormick Observatory on Mount Jefferson, Virginia, for 35 years. He was active in the fields of photometry, astrometry and spectral classification. The official was published by the Minor Planet Center on 20 February 1976 ().

Adolph Christian Wilhelm Schur, RAS Associate (15 April 1846 – 1 July 1901) was a German astronomer and professor of astronomy at the University of Göttingen. He held important positions at multiple observatories throughout his career, namely deputy director of the Strasbourg Observatory and director of the Göttingen Observatory. His main work was in astrometry, although he focused on publishing astronomical catalogues in his later life.

Illustration of the use of interferometry in the optical wavelength range to determine precise positions of stars. Courtesy NASA/JPL-Caltech 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 the Solar System and our galaxy, the Milky Way.

On 19 January 2029, will pass from Venus. The close approach distance to Venus in 2029 will determine how close the asteroid will pass to Earth in 2041. Before the November 2011 observations, the uncertainties in the post-2029 trajectory showed that the asteroid would pass somewhere between and of Earth in 2041. Radar astrometry in November 2011 clarified the Earth passage in 2041 and beyond.

It was called 66479 Healy after the founder of the JBO. Healy was also an original contributor to Burnham's Celestial Handbook. The JBO established by Healy operates a 32-inch Ritchey Chretien reflector chiefly for minor planet astrometry and is credited with over 500 discoveries.David Healy - astrophotographer After his chief co-discoverer Jeffrey Medkeff died in 2008, Dave decided to participate in the search for exo-planets.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Tom Gehrels used Palomar's 48-inch Samuel Oschin telescope and shipped the photographic plates to the van Houten's at Leiden Observatory, where astrometry was carried out. The trio are credited with more than 4600 minor planet discoveries.

In this case, the two stars can also be split by differential astrometry. The magnitude 4.18 primary has a mass of and the fainter secondary, . The primary is an F-type main-sequence star radiating 4.3 times the Sun's luminosity, and the magnitude 6.48 secondary is K-type with 0.6 times the luminosity of the Sun. The two orbit each other every with an eccentricity of 0.15.

Despite his involvement in the Barnard's Star affair 23 years earlier, Gatewood himself created a similar controversy. Gatewood predicted the existence of planets around nearby stars and studied these stars intensely attempting to detect planets by astrometry. Gatewood began studying Lalande 21185 soon after completing his thesis in the early 1970s. He failed to detect any planets at that time but was not discouraged.

This was the SM4 mission. An example of astrometry science with the Hubble FGS system is observations of the Low-Mass Binary star system L722-22. Observations were taken of the system in 1990s, and the data helped determine the mass of each of the components of L722-22, which is also known as LHS 1047 and GJ 1005. The FGS are white-light shearing interferometers.

Currently the most precise distance estimate of 2MASS 0415−0935 is published in 2012 by Dupuy & Liu trigonometric parallax, measured under The Hawaii Infrared Parallax Program: 175.2 ± 1.7 milliseconds of arc, corresponding to a distance 5.71 ± 0.05 pc, or 18.62 ± 0.18 ly. A less precise parallax of this object, measured under U.S. Naval Observatory Infrared Astrometry Program, was published in 2004 by Vrba et al.

Epsilon Pegasi (Latinised from ε Pegasi, abbreviated Epsilon Peg, ε Peg), formally named Enif , is the brightest star in the northern constellation of Pegasus. With an average apparent visual magnitude of 2.4, this is a second- magnitude star that is readily visible to the naked eye. The distance to this star can be estimated using parallax measurements from the Hipparcos astrometry satellite, yielding a value of around .

William H. "Bill" Jefferys (born 1940) is an American astronomer. He is a Harlan J. Smith Centennial Professor of Astronomy (Emeritus) of astronomy at The University of Texas at Austin, and an adjunct professor of statistics at the University of Vermont. Jefferys specialized in astrometry, celestial mechanics, and astrophysics, including the kinematics and dynamics of astronomical bodies. He has also worked in the field of Bayesian statistics, particularly with astronomical applications.

VideoFile; April 29, 2019) (blue dots = artificial satellites; pink = International Space Station) Apophis was discovered on June 19, 2004, by Roy A. Tucker, David J. Tholen, and Fabrizio Bernardi at the Kitt Peak National Observatory. On December 21, 2004, Apophis passed from Earth. Precovery observations from March 15, 2004, were identified on December 27, and an improved orbit solution was computed. Radar astrometry in January 2005 further refined its orbit solution.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The survey designation "P-L" stands for "Palomar–Leiden", named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The survey designation "P-L" stands for "Palomar–Leiden", named after Palomar and Leiden observatories, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope –also known as the 48-inch Schmidt Telescope – and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden, where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "P-L" stands for "Palomar–Leiden", named after Palomar and Leiden observatories, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

A significant expansion of the catalog, Guide Star Catalog II, was published in 2008. The Guide Star Catalog II (GSC-II) was compiled by the Catalog and Surveys branch of the Space Telescope Science Institute and the astrometry team of the Astronomical Observatory of Torino (Italy). It has entries for 945,592,683 stars, and has positions, classifications, and magnitudes for 455,851,237 stars. The latest revision of this version (2.3.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The Northolt Branch Observatories (NBO; Observatory codes: Z80, Z48 and Z37) is an astronomical observatory located in London, England. NBO collects follow-up astrometry of Near-Earth asteroids and other small Solar System objects. It focuses on public outreach, sharing images, videos and information about asteroids on social media. The two main belt asteroids 72834 Guywells and 128345 Danielbamberger are named after members of the Northolt Branch Observatories team.

In June 2020, the planet's existence was confirmed using Hubble astrometry data from c. 1995, allowing its inclination and true mass to be determined. Also in June 2020, a possible direct imaging detection of Proxima c was published. The detected source is too bright for a planet of Proxima c's mass and age, implying that the planet may have a ring system with a radius of around 5 .

Chernykh was born in the Russian city of Usman in Voronezh Oblast, in present-day Lipetsk Oblast. He specialized in astrometry and the dynamics of small bodies in the Solar System and worked at the Crimean Astrophysical Observatory from 1963. Chernykh discovered two periodic comets 74P/Smirnova–Chernykh and 101P/Chernykh. He also discovered a very large number of asteroids, including notably 2867 Šteins and the Trojan asteroid 2207 Antenor.

A fundamental aspect of astrometry is error correction. Various factors introduce errors into the measurement of stellar positions, including atmospheric conditions, imperfections in the instruments and errors by the observer or the measuring instruments. Many of these errors can be reduced by various techniques, such as through instrument improvements and compensations to the data. The results are then analyzed using statistical methods to compute data estimates and error ranges.

The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1; obs. code: F51 and Pan-STARRS2 obs. code: F52) located at Haleakala Observatory, Hawaii, US, consists of astronomical cameras, telescopes and a computing facility that is surveying the sky for moving or variable objects on a continual basis, and also producing accurate astrometry and photometry of already-detected objects. In January 2019 the second Pan-STARRS data release was announced.

Some fields, such as astrometry, are purely astronomy rather than also astrophysics. Various departments in which scientists carry out research on this subject may use "astronomy" and "astrophysics", partly depending on whether the department is historically affiliated with a physics department, and many professional astronomers have physics rather than astronomy degrees. Some titles of the leading scientific journals in this field include The Astronomical Journal, The Astrophysical Journal, and Astronomy & Astrophysics.

Hunter was appointed an assistant at the Royal Observatory, Greenwich in 1937, at a time when the observatory was under the directorship of Sir Harold Spencer Jones, the Astronomer Royal. Hunter served as head of the observatory's Department of Astrometry and Astrophysics from 1937 to 1956. In 1937 he married Joan Portnell. He worked on measuring the distances of stars using photography with the Greenwich 26-inch diameter refracting telescope.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation stands for "Palomar–Leiden", named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope – also known as the 48-inch Schmidt Telescope – and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

Under the direction of Peter van de Kamp this observatory made numerous claims of planetary systems and discoveries based on astrometry using the photographic plates made with the refractor telescope. These plates were found to have a systematic error that was misinterpreted as the effect of a planetary system on the parent star. This error was identified as early as 1973 and confirmed by the observatory in the 1980s.

This is a binary star system with an orbital period of 52.1 days and an eccentricity of 0.22. Only the primary star can be directly detected, via Doppler shifts or perturbations around the system's barycenter. Using spectroscopy and astrometry, the nature of the secondary star can be inferred. The primary star is an F-type main-sequence star with a stellar classification of F8V, 4% more massive than the Sun.

The BCRS was designed to support the extremely-high-precision measurements of position and motion required in astrometry. One critical factor in achieving that precision lies in how general relativistic effects are determined and measured. Both systems incorporate standards that enable the consistency and ready comparability of the resulting spacetime coordinates among astrometric measurements taken worldwide. They provide a metric tensor to establish a consistent frame of reference for observations.

The deflection is the difference between the true zenith as determined by astrometry, and the apparent zenith as determined by a plumb-line Observatories were constructed to the north and south of the mountain, plus a bothy to accommodate equipment and the scientists. The ruins of these structures remain on the mountainside. Most of the workforce was housed in rough canvas tents. Maskelyne's astronomical measurements were the first to be conducted.

He was the Hubble Space Telescope Astrometry Science Team leader, and participated in the project that repaired the Hubble Space Telescope after the discovery of its initial optical defect. Jefferys served as chairman of The University of Texas Department of Astronomy from 1994 to 1998. He retired from the University of Texas in 2004 and moved to Vermont in 2005, where he accepted an appointment as adjunct professor of statistics at the University of Vermont.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

With the initial detection of an extrasolar X-ray source, the first question usually asked is "What is the source?" An extensive search is often made in other wavelengths such as visible or radio for possible coincident objects. Many of the verified X-ray locations still do not have readily discernible sources. X-ray astrometry becomes a serious concern that results in ever greater demands for finer angular resolution and spectral radiance.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "T-3" stands for the third Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "T-1" stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory conducted in 1971. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "T-2" stands for the second Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio is credited with the discovery of several thousand asteroid discoveries.

The survey designation "T-3" stands for the third Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory conducted in 1977. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "T-1" stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The survey designation "T-3" stands for the third Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "T-3" stands for the third Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "P-L" stands for "Palomar–Leiden", named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

Hamal , designation Alpha Arietis (α Arietis, abbreviated Alpha Ari, α Ari), is the brightest star in the northern zodiacal constellation of Aries. With an apparent visual magnitude of 2.0, it is the mean 50th brightest star in the night sky. Based upon parallax measurements made with the Hipparcos astrometry satellite, Hamal is about from Earth. It is a giant star that may host an orbiting planet with a mass greater than Jupiter.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "T-3" stands for the third Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The survey designation "T-2" stands for the second Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

It is itself a spectroscopic binary, although little is known about the two components. The combined spectrum is of an F4 main sequence star. It is thought to be physically associated with the supergiant primary and a member of a loose cluster of stars around Zeta Geminorum. A combination of photometry, spectroscopy, and astrometry has identified 26 stars approximately 355 parsecs away, which are likely to be members of the birth cluster of Zeta Geminorum.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

In 2007 Hubble Space Telescope data indicated a distance of about 540 light years, though this value caused difficulties with the theory of dwarf novae; this was checked during 2010–2012 using radio astrometry with VLBI, which yielded a smaller distance of . This value is much more in accord with the old (≈400 light-year) value, and it removes completely the difficulties the larger HST distance made for the theory of dwarf novae.

The first publication of the results of this work started in 1925 (Transactions of the Yale University Observatory, v. 4) and the work concluded in the 1980s. He made major contributions to astrometry. He was elected to the American Philosophical Society (1912), the National Academy of Sciences (1916) and the American Academy of Arts and Sciences and served as president of the American Astronomical Society (1919–1922), and the International Astronomical Union (1932–1935).

The survey designation "T-1" stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The provisional survey designation "P-L" stands for Palomar–Leiden, named after the Palomar and Leiden observatories, which collaborated on the fruitful Palomar–Leiden survey in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope, also known as the 48-inch Schmidt Telescope, and shipped the photographic plates to Cornelis and Ingrid van Houten at Leiden Observatory, where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "T-1" stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "T-3" stands for the third and last Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

The survey designation "T-1" stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "T-2" stands for the second Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

This minor planet was named after Canadian astronomer and author Clifford Cunningham, who is best known for his 1988 published book Introduction to Asteroids and 5-volume history of asteroid studies published by Springer in 2016 and 2017. He received his PhD in the history of astronomy in 2015. His astronomical work includes astrometry and photometry of minor planets. The approved naming citation was published by the Minor Planet Center on 10 April 1990 ().

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "P-L" stands for "Palomar–Leiden", named after Palomar and Leiden observatories, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Tom Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "T-1" stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "T-1" stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

At first the observatory has been used for satellite astrometry (1960s-1970s). Between 1964 and 1974 more than 1000 Soviet satellites were observed and data sent to Mission Control Centre in Moscow for orbit corrections. Later, during the 1970s and 1980s, Photo-electric surveys of more than 200 catalogue double and multiple galaxies (1970s-1980s) were carried out. Holmberg effect was used to confirm or rule out physical and visual systems (binaries and multiplets).

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

Shanghai Astronomical Observatory (SHAO), is an astronomical observatory in Shanghai. It has a long history of astrometry, and also operates the Sheshan 25-m radio telescope as part of the Chinese VLBI array and the EVN. It was formed in 1962 from the merger of the Xujiahui (originally spelt Ziikawei) and Sheshan (Zose) observatories in Shanghai. It was involved with the Chang'e 1 moon mission as the VLBI array is used for position determinations.

In some cases, active space probes on solar orbits have been observed by NEO surveys and erroneously catalogued as asteroids before identification. During its 2007 flyby of Earth on its route to a comet, ESA's space probe Rosetta was detected unidentified and classified as asteroid , with an alert issued due to its close approach. The designation was similarly removed from asteroid catalogues when the observed object was identified with Gaia, ESA's space observatory for astrometry.

The components of multiple stars can be specified by appending the suffixes A, B, C, etc., to the system's designation. Suffixes such as AB may be used to denote the pair consisting of A and B. The sequence of letters B, C, etc. may be assigned in order of separation from the component A.Format, The Washington Double Star Catalog , Brian D. Mason, Gary L. Wycoff, and William I. Hartkopf, Astrometry Department, United States Naval Observatory.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "P-L" stands for "Palomar–Leiden", named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "P-L" stands for "Palomar–Leiden", named after the Palomar and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "T-2" stands for the second Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory during the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

Consequently, a definitive mass and density estimate for Huya cannot be derived from the satellite's orbit. Based on archival Hubble images of Huya taken in 2002, the satellite's angular separation distance from Huya is approximately 60 to 80 arcseconds, corresponding to an approximate distance of . Astrometry of the satellite's changing position around Huya from two Hubble images taken one day apart in 2002 indicates a rough orbital period estimate of about 3.2 days.

A magnetometer and data logger are installed at The Cottage to collect data for Dr. Yuki Obana of the Osaka Electro-Communication University. The data is used for solar wind research. Society members are very active in occultation observation using the C14 telescope housed in the Beverly-Begg Observatory with a Watec astronomical video camera and IOTA-VTI video timing system. A SBIG ST8300M camera is used for Astrometry and Photometry in several observation programs.

This allows a larger useful field of view, and the remaining astigmatism is symmetrical around the distorted objects, allowing astrometry across the wide field of view. However, the astigmatism can be reduced by including a third curved optical element. When this element is a mirror, the result is a three-mirror anastigmat. In practice, the design may also include any number of flat fold mirrors, used to bend the optical path into more convenient configurations.

As a part of the Comenius University, the observatory provides research opportunity for students, and the staff offers guidance for the Master and PhD theses. The research is mainly aimed at the interplanetary matter. Until January 2014, 175 numbered and 34 unnumbered asteroids were discovered at the observatory including two Near Earth Objects 2005 GB34 and 2008 UW5. The observing time is mostly assigned for the photometry of asteroids and comets and astrometry.

The survey designation "T-2" stands for the second Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroid discoveries.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "T-1" stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Cornelis and Ingrid van Houten at Leiden Observatory where astrometry was carried out. The trio of astronomers are credited with the discovery of 4,620 minor planets.

The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

An updated reference frame ICRF2 was created in 2009. The update was a joint collaboration of the International Astronomical Union, the International Earth Rotation and Reference Systems Service, and the International VLBI Service for Geodesy and Astrometry. ICRF2 is defined by the position of 295 compact radio sources (97 of which also define ICRF1). Alignment of ICRF2 with ICRF1-Ext2, the second extension of ICRF1, was made with 138 sources common to both reference frames.

The following is a list of 456 extrasolar planets that were only detected by radial velocity method –– 31 confirmed and 323 candidates, sorted by orbital periods. Since none of these planets are transiting or directly observed, they do not have measured radii and generally their masses are only minimum. The true masses can be determined when astrometry calculates the inclination of the orbit. There are 160 members of the multi-planet systems –– 21 confirmed and 139 candidates.

The Observatory employs 45 researchers along with 60 engineers and technicians to accomplish staff the several major departments and several labs of the observatory. These are combined with 80 other people who perform administrative duties, workshops, garage, and a staff of guards. The departments and labs are designed to focus on scientific and technical aspects of observatory sciences. The departments are as follows: Plasma astrophysics, Extragalactic radio astronomy, Pulsar physics, Space radio spectroscopy, and Pulsar astrometry.

Classical astrometry concerns only motions in the plane of the sky and ignores the star's radial velocity, i.e. its space motion along the line-of-sight. Whilst critical for an understanding of stellar kinematics, and hence population dynamics, its effect is generally imperceptible to astrometric measurements (in the plane of the sky), and therefore it is generally ignored in large-scale astrometric surveys. In practice, it can be measured as a Doppler shift of the spectral lines.

These are combined with 80 other people who perform administrative duties, workshops, garage, and a staff of guards. The departments and labs are designed to focus on scientific and technical aspects of observatory sciences. The departments are as follows: Plasma astrophysics, Extragalactic radio astronomy, Pulsar physics, Space radio spectroscopy, and Pulsar astrometry. The laboratories are as follows: Radio astronomy equipment, Automation radio astronomy research, Computer engineering and information technology, and Radio telescopes of the meter wavelength range.

The survey designation "T-3" stands for the third Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Cornelis and Ingrid van Houten-Groeneveld at Leiden Observatory where astrometry was carried out. The trio of astronomers are credited with the discovery of several thousand minor planets.

Lennart Lindegren is a member of the staff at Lund Observatory, Sweden, where he obtained his PhD in 1980, and became a full professor of astronomy in 2000.Official webpage of Lennart Lindegren at Lund Observatory website. Space astrometry and its various applications has been his main focus in astronomy since 1976. His career has been marked by his continuous involvement in, leadership of, and profound contributions to, ESA's Hipparcos and Gaia missions over their entire duration.

The survey designation "T-3" stands for the last of three Palomar–Leiden Trojan surveys, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

The survey designation "T-3" stands for the third and last Palomar–Leiden Trojan survey, which was named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

François Mignard (born 1949) is a French astronomer and the director of the CERGA Observatory () of the Observatoire de la Côte d'Azur in southern France. He is an expert in space astrometry and Solar System dynamics, and played major roles in the European Space Agency's Hipparcos and Gaia missions. Mignard is an active member in several commissions of the International Astronomical Union and chairman of its working group that amends the standards for the International Celestial Reference System.

The Anglo-Australian Near-Earth Asteroid Survey (AANEAS) operated from 1990-96, becoming one of the most prolific programs of its type in the world. Apart from leading to the discovery of 38 near-Earth asteroids, 9 comets, 63 supernovae, several other astronomical phenomena and the delivery of a substantial proportion of all NEA astrometry obtained worldwide (e.g., 30% in 1994-95), AANEAS also led to many other scientific advances which were reported in the refereed literature.

The Panoramic Survey Telescope and Rapid Response System (Pan- STARRS) is a pair of telescopes plus a computing facility that surveys the sky on a continual basis, providing accurate astrometry and photometry of detected objects. By detecting any differences from previous observations of the same areas of the sky, it has discovered over 5,700 new asteroids, comets, variable stars and other celestial objects. Currently, the PS1 telescope is in operation and the PS2 is in its commissioning phase.

Lippincott was born in 1920 and attended college at the University of Pennsylvania College for Women in the 1940s, where she played on the women's basketball team. After graduation from the University of Pennsylvania, Lippincott attended Swarthmore College, where she worked closely with Peter van de Kamp on many astrometry projects between 1945 and his retirement in 1972. She wrote his obituary when he died in 1995. She became observatory director after Peter van de Kamp retired in 1972.

He was born at Maillen. Debehogne worked at the Royal Observatory of Belgium () in Uccle, and specialized in astrometry of comets and minor planets. He is credited by the Minor Planet Center with the discovery of over 700 numbered minor planets, including the Trojan asteroids (6090) 1989 DJ and 65210 Stichius (the latter with Eric Walter Elst) and hundreds of asteroids of the main-belt. He died on 9 December 2007, at the age of 78 in Uccle.

Visible in the same field and as prominent as the red supergiants in infrared images is the carbon star MZ Cephei, which is much closer to us than NGC 7419. It is a slow irregular variable star with a range of 14.7 - 15.4. The visually brightest star in the core region of the cluster is a yellow giant, placed at around 500 parsecs by Gaia astrometry. The even brighter nearby star HD 216721 is also a foreground object.

Gamma Eridani (γ Eridani, abbreviated Gamma Eri, γ Eri), formally named Zaurak , is a variable star in the constellation of Eridanus. It is visible to the naked eye with an apparent visual magnitude that varies around 2.9, and lies at a distance of about 203 light years from the Sun, as determined by the Hipparcos astrometry satellite. This is an evolved red giant star that is currently on the asymptotic giant branch of the Hertzsprung–Russell diagram.

She did major works in the field of photographic astrometry and studies of the Sun . She determined (1936–1937) the proper motions of stars in the eastern branch of the dark nebulae of Perseus, Taurus and the Orion Nebula . She studied observations of double stars using a 38 cm astrograph . She was one of the leaders of the expedition which monitored the solar corona at various points of the USSR during the total solar eclipse on June 19, 1936.

Today, there are six telescopes at the observatory. The Double Refractor aside, there is also the 16 cm Schröder Refractor, which was used for the Cordoba Durchmusterung (the southern extension of the Bonner Durchmusterung). 1 metre telescope The observatory was an outstation of the Argelander Institute for Astronomy of the University of Bonn. Many students have obtained their diploma or doctorate, and important scientific work in astrometry and photometry of stars of the Milky Way was carried out.

Edward Fomalont (born May 14, 1940) is an American scientist working at the National Radio Astronomy Observatory. He specializes in radio galaxies, X-ray binary systems, astrometry, and general relativity. He has published more than 330 papers in peer-reviewed journals and proceedings of scientific conferences. In 1975, Fomalont and Richard Sramek made a first radio- interferometric occultation experiment to test the theory of general relativity by measuring the bending of microwave radiation in the gravitational field of the Sun.

This minor planet was named in honor of its discoverer, the American astronomer Edward L. G. Bowell (born 1943), based on a proposal by MPC's longtime director Brian G. Marsden. Astronomer at the Lowell Observatory and a prolific discoverer of minor planets himself, Bowell has made significant contributions on the observatory's UBV photometry and astrometry programs for minor planets, including the prediction of occultation events. The official naming citation was published by the Minor Planet Center on 1 January 1981 ().

Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model. Most of the topics in astrophysics, astrochemistry, astrometry, and other fields that are branches of astronomy studied by theoreticians involve X-rays and X-ray sources.

Already by the end of 1976, Lindegren had produced a set of definitive technical notes and simulations showing how to obtain a `rigid sphere' with all astrometric parameters from a scanning satellite. Innovation, efficiency, completeness, clarity, and mathematical rigour have been the hallmarks of his many and varied fundamental contributions to space astrometry since that time. From 1990 Lennart Lindegren led the Consortium NDAC (Northern Data Analysis Consortium) sharing with FAST (led by Jean Kovalevsky) the data processing of Hipparcos.

The discovery was made in a survey of faint Trojans, one night after the discovery of 1870 Glaukos. The trio of Dutch and Dutch–American astronomers also collaborated on the productive Palomar–Leiden survey in the 1960s, using the same procedure as for this (smaller) survey: Tom Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Cornelis and Ingrid van Houten at Leiden Observatory where astrometry was carried out.

61, No. 363, p.274; Bibliographic Code: 1949PASP...61..274 Blanco later served as the Director of the Astrometry and Astrophysics Division of the United States Naval Observatory. The U.S. Naval Observatory (USNO) provides a wide range of astronomical data and products, and serves as the official source of time for the U.S. Department of Defense and the standard of time for the entire United States.Naval Oceanography Portal He also served in Java, Indonesia for UNESCO in the position of astronomer.

This minor planet was named after Latvian cosmic geodesist Jānis Balodis, head of the Astronomical Observatory at University of Latvia. Balodis research includes astrometry, observations of artificial satellites using laser, as well as computational methods for astrometric interpretations of photographic plates. The Crimean minor planet service has used his algorithms for a long time. (The honored astronomer should not to be confused with Soviet army General Jānis Balodis.) The official naming citation was published by the Minor Planet Center on 12 September 1992 ().

The Zooniverse project Catalina Outer Solar System Survey is a citizen science project and it is listed as a NASA citizen science project. In this project, the volunteers search for trans-Neptunian objects (TNOs) in pre-processed images of the Catalina Sky Survey. Computers can detect the motion of TNOs, but humans have to check if this motion is real. Upon agreement with the volunteers, they will be cited as "measurers" in the submission of the astrometry to the Minor Planet Center.

The unusual measurements were not readily identifiable as being due to orbital motion, and it was referred to as having a stochastic solution to its astrometry. Later analysis derived an orbit, although nothing is known about the companion except its approximate mass and motion about the visible star. The pair orbit each other with a period of 452 days and an eccentricity of 0.2. The primary, component A, is a metal-lined Am star with a stellar classification of A1mA3-A9.

Much to the annoyance of Valentiner, now appointed Professor of the University of Karlsruhe, no new observatory was built. He decided to apply for a position at Königstuhl near Heidelberg. After the establishment of the "Grand Duchy Mountain Observatory" (today's Heidelberg-Königstuhl State Observatory) in the year 1898 Valentiner was placed over the Department of Astrometry, which stood in competition with the Astrophysics Department under Max Wolf. When Valentiner retired in 1909 the two departments were merged under the direction of Wolf.

This minor planet was named after the astronomer couple Bart Bok (1906–1983) and Priscilla Fairfield Bok (1896–1975), in recognition for their contribution to astrometry of small Solar System bodies. Both astronomers studied the structure of the southern Milky Way and fostered astronomy in the Southern Hemisphere. Bok was the first numbered discovery made with the Stewart Observatory's 90-inch Bok Telescope. The body's name was proposed by the discovering astronomer and by Alan C. Gilmore from New Zealand.

It varies slightly in apparent magnitude, ranging from 6.44 to 6.49 over a 10.3 day period. While smaller than the Sun, it is relatively large for a flare star. Most flare stars are red M-type dwarfs. In 2019 a team of researchers analyzing the astrometry, radial velocity measurements, and images of Fomalhaut B suggested the existence of a planet orbiting the star with a mass of Jupiter Masses, and an poorly defined orbital period of up to 80 years.

The Hubble Space Telescope has three fine guidance sensors (FGSs). Two are used to point and lock the telescope onto the target, and the third can be used for position measurements - also known as astrometry. Because the FGSs are so accurate, they can be used to measure stellar distances and also to investigate binary star systems. After locking on to a bad guide star, Hubble's tracking system captured this image: the prominent red streaks are actually stars in globular cluster NGC 288.

Van de Kamp taught Roman in a solo lecture course on astrometry, introducing her to learning about professional astronomy by encouraging her use of the astronomy library. She graduated in February 1946, and van de Kamp suggested that she continue astronomy in graduate studies at the University of Chicago, which was then rebuilding its astronomy department post-World War II. Years later, Roman continued to be involved with her alma mater, serving on the Swarthmore Board of Managers from 1980 to 1988.

The large- field Ritchey–Chrétien telescope was 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 (milliarcsecond 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.

Mizar is a second-magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris (Latinised as Zeta Ursae Majoris). It forms a well-known naked eye double star with the fainter star Alcor, and is itself a quadruple star system. The whole system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group.

Retrieved 2015-01-13 Raab's most important observations include precise astrometry of the comet Shoemaker–Levy 9, which he observed together with Erich Meyer and Erwin Obermair in 1993. These observations have significantly contributed to the subsequent prediction of the impact of this comet on the planet Jupiter.IAUC 5800: Periodic Comet Shoemaker-Levy 9 (1993e). Retrieved 2015-01-13. On 10 August 1997, he discovered the asteroid 13682 Pressberger together with Erich Meyer at the private observatory Meyer/Obermair in Davidschlag (municipality Kirchschlag bei Linz, Austria).

While the discovery date aligns with the second Palomar–Leiden Trojan survey, Kalchas did not receive a prefixed survey designation, which was assigned for the discoveries made by the fruitful collaboration between the Palomar and Leiden observatories in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

While the discovery date aligns with the second Palomar–Leiden Trojan survey, Euneus has not received a prefixed survey designation, which was assigned to the discoveries made by the fruitful collaboration between the Palomar and Leiden observatories in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

Despite being discovered during the second Palomar–Leiden Trojan survey in 1973, Euryalos has not received a provisional survey designation prefixed with "T-2". The survey was a fruitful collaboration between the Palomar and Leiden observatories during the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

Despite being discovered during the second Palomar–Leiden Trojan survey in 1973, Amphilochos has not received a provisional survey designation prefixed with "T-2". The survey was a fruitful collaboration between the Palomar and Leiden observatories during the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

This minor planet was named after the Australian Perth Observatory for its many contributions to astronomy including the Perth 70 meridian catalogue, the co- discovery of the rings of Uranus, and observational work on Comet Halley both in 1910 and 1986. The observatory was founded near the city of Perth in 1896, and moved to Bickley in 1965. The observatory is known for its astrometry and photometry on small Solar System bodies. The official naming citation was published by the Minor Planet Center on 17 August 1989 ().

While the discovery date aligns with the second Palomar–Leiden Trojan survey, Prylis has not received a prefixed survey designation, which was assigned to the discoveries made by the fruitful collaboration between the Palomar and Leiden observatories in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

Despite being discovered during the second Palomar–Leiden Trojan survey in 1973, Nauplius has not received a provisional survey designation prefixed with "T-2". The survey was a fruitful collaboration between the Palomar and Leiden observatories during the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

While the discovery date aligns with the second Palomar–Leiden Trojan survey, Menestheus has not received a prefixed survey designation, which was assigned for the discoveries made by the fruitful collaboration between the Palomar and Leiden observatories in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

HD 108541, also known by its Bayer designation u Centauri is a star located in the constellation Centaurus, It is also known as HR 4748. The apparent magnitude of the star is about 5.4, meaning it is only visible to the naked eye under excellent viewing conditions. Its distance is about 440 light-years (140 parsecs), based on its parallax measured by the Hipparcos astrometry satellite. The spectral type of HD 108541 is B8/9V, meaning it is a late B-type main sequence star.

The Palomar Testbed Interferometer (PTI)Colavita, M. M., et al. (1999), The Palomar Testbed Interferometer, ApJ, 510, 505 was a near-IR, long-baseline stellar interferometer located at Palomar Observatory in north San Diego County. It was developed to demonstrate the utility of ground-based differential astrometry in the search for planets around nearby stars, and to develop key technologies for the Keck Interferometer and space-based missions. PTI is no longer an operating facility, but previously collected data can be accessed through the PTI archive.

While the discovery date aligns with the second Palomar–Leiden Trojan survey, Eurybates has not received a prefixed survey designation, which was assigned for the discoveries made by the fruitful collaboration between the Palomar and Leiden observatories in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

While the discovery date aligns with the second Palomar–Leiden Trojan survey, Theotes has not received a prefixed survey designation, which was assigned to the discoveries made by the fruitful collaboration between the Palomar and Leiden observatories in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with the discovery of several thousand asteroids.

Hipparcos satellite astrometry also suggested that Arcturus is a binary star, with the companion about twenty times dimmer than the primary and orbiting close enough to be at the very limits of humans' current ability to make it out. Recent results remain inconclusive, but do support the marginal Hipparcos detection of a binary companion., and see references therein. In 1993, radial velocity measurements of Aldebaran, Arcturus and Pollux showed that Arcturus exhibited a long-period radial velocity oscillation, which could be interpreted as a substellar companion.

When the Caribbean bolide report came in from the GOES-16 weather satellite it was possible to link the ATLAS astrometry to it. Three additional precovery observations by Pan-STARRS 2 were then located and extended the observation arc to 2.3 hours. Using all seven observations, Scout then obtained a significantly better orbit determination with an impact rating of "elevated". The updated orbit shows that the asteroid was about 1.3 LD (500,000 km) from Earth when ATLAS-MLO observed it, 12 hours before impact.

The signal could come from those variations instead of the planet orbiting the star or suggests that rotational modulation of the visibility of stellar surface activity is the source of the observed radial velocity variations.See, Finally, in 2003 the planet was confirmed; the planet is thought to be causing fluctuations in the system's magnetic field, causing visible activity. Preliminary astrometry in 2001 set its inclination at 179.5°; but it is now thought to be inclined according to the star's ecliptic, edge-on to Earth.

Kepler mission – new exoplanet candidates – as of June 19, 2017. Once suitable candidates have been found from Kepler data, it is necessary to rule out false positives with follow-up tests. Usually, Kepler candidates are imaged individually with more- advanced ground-based telescopes in order to resolve any background objects which could contaminate the brightness signature of the transit signal. Another method to rule out planet candidates is astrometry for which Kepler can collect good data even though doing so was not a design goal.

Epsilon Bootis (Izar) as seen in a small telescope Epsilon Boötis consists of a pair of stars with an angular separation of at a position angle of . The brighter component (A) has an apparent visual magnitude of 2.37, making it readily visible to the naked eye at night. The fainter component (B) is at magnitude 5.12, which by itself would also be visible to the naked eye. Parallax measurements from the Hipparcos astrometry satellite put the system at a distance of about from the Earth.

Radial velocities for Hipparcos Catalogue stars, to the extent that they are presently known from independent ground-based surveys, can be found from the astronomical database of the Centre de données astronomiques de Strasbourg. The absence of reliable distances for the majority of stars means that the angular measurements made, astrometrically, in the plane of the sky, cannot generally be converted into true space velocities in the plane of the sky. For this reason, astrometry characterises the transverse motions of stars in angular measure (e.g. arcsec per year) rather than in km/s or equivalent.

Its site is now the headquarters of the South African Astronomical Observatory. In accordance with its mandate, the principal activity of the Observatory was Astrometry and it was over its existence responsible for publishing many catalogues of star positions. In the 20th century it turned in part towards Astrophysics but by the nineteen- fifties the city lights of Cape Town had rendered work on faint objects impossible and a new site in the Karoo semi-desert was sought. An agreement to facilitate this was ratified on 23 September 1970.

While was estimated to be 470 meters in diameter, it was rated −0.40 on the Palermo Scale, placing it higher on the Sentry Risk Table than any other known object at the time. On 14 June 2019, Alessio Del Vigna and colleagues published a new analysis, which incorporates astrometry taken in 2019. Using both JPL's Sentry as well as NEODyS's CLOMON-2 system, the new data allowed a 4-sigma detection of the Yarkovsky effect at . The 2019 observations extended the observation arc from six years to ten years.

Maurizio Buscalioni The first director was the Italian astronomer Maurizio Buscalioni, who brought to the observatory equipment modern for its time. The focus was on weather and astrometry observations that included the first systematic measurements of atmospheric pressure, temperature, humidity and rainfall. He made astrometric observations to determine legal time and as well as the latitude of the Observatory. Buscalioni worked to establish contacts with the best observatories and astronomers of America and Europe. Buscalioni led the observatory for three years, submitting his final report in January 1894.

Blanco was employed by the University of Puerto Rico as an assistant professor of astrometry, until he was recruited in 1948 to assist in polishing, calibrating and maintaining the mirrors of the 200-inch Hale telescope in California. He entered the University of California, Berkeley, where he continued his studies and earned his master's degree and, in 1949, his Doctorate in astronomy.Astronomy In 1949, he returned to Puerto Rico and reassumed his duties at the University of Puerto Rico.Journal: Publications of the Astronomical Society of the Pacific, Vol.

He is depicted opposite Ptolemy in Raphael's painting The School of Athens, although this figure is popularly believed to be Strabo or Zoroaster. The rather cumbersome formal name for the ESA's Hipparcos Space Astrometry Mission was High Precision Parallax Collecting Satellite; it was deliberately named in this way to give an acronym, HiPParCoS, that echoed and commemorated the name of Hipparchus. The lunar crater Hipparchus and the asteroid 4000 Hipparchus are more directly named after him. He was inducted into the International Space Hall of Fame in 2004.

Despite being discovered during the second Palomar–Leiden Trojan survey in 1973, Azabu has not received a provisional survey designation starting with "T-2". This may be related to the swapped naming rights proposed by Tom Gehrels (see below). The survey was a fruitful collaboration between the Palomar and Leiden observatories during the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out.

This catalog of stars is significant not only for the intrinsic features of the stars themselves but also for the stars proximity to Earth. These low mass, low luminosity stars close by are uniquely situated for exo-planetary searches using astrometry or optical methods. The low mass of the star enables observers on Earth to see a large motion of the star for a given planetary mass. The low luminosity of the stars makes a direct optical or infrared telescopic survey for orbiting objects, such as planets, near the star possible.

Statue of an astronomer and the concept of the cosmic distance ladder by the parallax method, made from the azimuth ring and other parts of the Yale–Columbia Refractor (telescope) (c 1925) wrecked by the 2003 Canberra bushfires which burned out the Mount Stromlo Observatory; at Questacon, Canberra, Australian Capital Territory. At the base of the ladder are fundamental distance measurements, in which distances are determined directly, with no physical assumptions about the nature of the object in question. The precise measurement of stellar positions is part of the discipline of astrometry.

While daily administrative duties kept him busy, Nikoloff continued observing on all the Observatory's telescopes at night and on weekends. Nikoloff maintained a good relationship with the University of Western Australia, was a Foundation member and Fellow of the Astronomical Society of Australia, a life member of the Astronomical Association of Western Australia and a member of the IAU's original Commission 8 (Astrometry) and I (Fundamental Astronomy); he also continued the Observatory's public information services and tours. He retired on 4 January 1985 and died on 8 April 2015.

The third effect has to be handled individually. The star positions α, δ are compiled in several star catalogues of different volume and accuracy. Absolute and very precise coordinates of 1000-3000 stars are collected in fundamental catalogues, starting with the FK (Berlin ~1890) up to the modern FK6. Relative coordinates of numerous stars are collected in catalogues like the Bonner Durchmusterung (Germany 1852-1862, 200.000 rough positions), the SAO catalogue (USA 1966, 250.000 astrometric stars) or the Hipparcos and Tycho catalogue (110.000 and 2 million stars by space astrometry).

The open stellar cluster Hyades in Taurus extends over such a large part of the sky, 20 degrees, that the proper motions as derived from astrometry appear to converge with some precision to a perspective point north of Orion. Combining the observed apparent (angular) proper motion in seconds of arc with the also observed true (absolute) receding motion as witnessed by the Doppler redshift of the stellar spectral lines, allows estimation of the distance to the cluster (151 light-years) and its member stars in much the same way as using annual parallax.

Diagram showing how a smaller object (such as an extrasolar planet) orbiting a larger object (such as a star) could produce changes in position and velocity of the latter as they orbit their common center of mass (red cross). barycenter of solar system relative to the Sun. Apart from the fundamental function of providing astronomers with a reference frame to report their observations in, astrometry is also fundamental for fields like celestial mechanics, stellar dynamics and galactic astronomy. In observational astronomy, astrometric techniques help identify stellar objects by their unique motions.

Finally, on the construction of an observatory it was granted that the Karlsruhe instruments should be transferred to Heidelberg. On 20 June 1898, the "Großherzogliche Bergsternwarte" at Königstuhl (the present day Heidelberg Observatory) was ceremonially inaugurated by Frederick I, Grand Duke of Baden. The astronomical institute comprised two competing departments, the Astrophysics Department under Max Wolf, containing the instruments from his private observatory and the new foundation's instruments, and the Astrometry Department under Karl Wilhelm Valentiner, containing the Karlsruhe instruments. Valentiner was director of the Mannheim Observatory and had initiated the move to Karlsruhe.

One of the three fine guidance sensors photographed during Servicing Mission 2 in 1997 A fine guidance sensor (FGS) is an instrument on board a space telescope that provides high-precision pointing information as input to the observatory's attitude control systems. FGSs have been deployed on the Hubble Space Telescope, and will be deployed with a different technical approach on the James Webb Space Telescope. The system on Hubble uses an interferometric instrument In some specialized cases, such as astrometry, FGSs can also be used as scientific instruments.

VLBI is best known for imaging distant cosmic radio sources, spacecraft tracking, and for applications in astrometry. However, since the VLBI technique measures the time differences between the arrival of radio waves at separate antennas, it can also be used "in reverse" to perform earth rotation studies, map movements of tectonic plates very precisely (within millimetres), and perform other types of geodesy. Using VLBI in this manner requires large numbers of time difference measurements from distant sources (such as quasars) observed with a global network of antennas over a period of time.

In May 2009, astronomers from NASA's Jet Propulsion Laboratory, Pasadena, California, announced that they had found evidence of a planet orbiting VB 10, which they designated VB 10b. The Hale telescope at the Palomar Observatory was used to detect evidence of this planet using the astrometry method. The new planet was claimed to have a mass 6 times that of Jupiter and an orbital period of 270 days. However, subsequent studies using Doppler spectroscopy failed to detect the radial velocity variations that would be expected if such a planet was orbiting this small star.

The distance to the North America has long been controversial, because there are few precision methods for determining how far away an HII region lies. Until 2020, most astronomers accepted a value of 2000 light years, though estimates ranged from 1500 to 3000 light years. But in 2020, this nebula's distance was pinned down with unprecedented accuracy, after the Gaia astrometry satellite measured the precise distances to 395 stars lying within the HII region. The data show that the North America and Pelican nebulae lie 2,590 light years away (795±25 parsecs).

The BCRS and GCRS were also designed so as to make transformations of their coordinates between themselves and other reference systems possible, though the conversions are not by any means straightforward. There are two software libraries of IAU-sanctioned algorithms for manipulating and transforming among the BCRS and other reference systems: the Standards of Fundamental Astronomy (SOFA) system and the Naval Observatory Vector Astrometry Subroutines (NOVAS). The orientation of the BCRS/ICRS axes also align within 0.02 arcsecond of the Earth's mean equator and equinox for the Fifth Fundamental Catalog (FK5) J2000.0 epoch.

In 2010 this dish was used for several Very Long Baseline Interferometry observationsTzioumis et al, Evolution of the pc- scale structure of PKS 1934-638 revisited: first science with the ASKAP and New Zealand telescopes, The Astronomical Journal 140 (2010) 1506-1510 as part of the Australian Long Baseline Array. It will also from 2011 be part of the International VLBI Service for Geodesy and Astrometry. As such, it is also co- located with a LINZ/GeoNet 'PositioNZ' GNSS station to help future inclusion in the definition of the International Terrestrial Reference Frame (ITRF).

The star is named after the American astronomer E. E. Barnard, who in 1916 measured its proper motion as 10.3 arcseconds per year relative to the Sun, the highest known for any star. The star had previously appeared on Harvard University photographic plates in 1888 and 1890. Barnard's Star is among the most studied red dwarfs because of its proximity and favorable location for observation near the celestial equator. Historically, research on Barnard's Star has focused on measuring its stellar characteristics, its astrometry, and also refining the limits of possible extrasolar planets.

Servicing Mission 3B flown by Columbia in March 2002 saw the installation of a new instrument, with the FOC (which, except for the Fine Guidance Sensors when used for astrometry, was the last of the original instruments) being replaced by the Advanced Camera for Surveys (ACS). This meant COSTAR was no longer required, since all new instruments had built-in correction for the main mirror aberration. The mission also revived NICMOS by installing a closed-cycle cooler and replaced the solar arrays for the second time, providing 30 percent more power.

The current NPOI siderostat array remains the world's only long-baseline (437-meter) optical interferometer that can simultaneously co- phase six elements. NPOI is expected to grow significantly in capability with the pending addition of four 1.8-meter aperture IR/Optical telescopes into the current array. The enhanced array will also employ adaptive optics techniques. This layout and increased sparse aperture will permit significant improvements to the science capability, from a tenfold increase in measuring ever-fainter wide-angle astrometry targets, to improved positional determination for numerous binary and flare stars.

The 55 Cancri system is located fairly close to the Solar System: the Gaia astrometry satellite measured the parallax of 55 Cancri A as 79.4274 milliarcseconds, corresponding to a distance of 12.59 parsecs (41.06 light years). 55 Cancri A has an apparent magnitude of 5.95, making it just visible to the naked eye under very dark skies. The red dwarf 55 Cancri B is of the 13th magnitude and only visible through a telescope. The two components are separated by an estimated distance of 1065 AU (one thousand times the distance from the Earth to the Sun).

In addition, in 1951 he published with Otto Heckmann and Pascual Jordan an important work for the extension of Einstein's theory of gravity. After being appointed to the Astronomical Calculation Institute, Fricke concentrated on fundamental astrometry. He worked specifically to improve the fundamental reference system, a series of measurements of the position and motions of a series of fundamental stars that is important for study of kinematics and dynamics of objects within the Galactic system. The production of this kind of fundamental catalogue, which provided the astronomical representation of an inertial system, was part of the institute's important work.

Photographic plates from this observatory, taken at the same time, were used by Van de Kamp for his erroneous claim of a planetary system for Barnard's Star. The photographic plates made with the Sproul 24-inch refractor and used for these and other studies were later shown to be flawed. The claims of planetary companions for both stars were refuted in 1974 with astrometric measurements made by George Gatewood of the Allegheny Observatory. In 1996 the same George Gatewood prominently announced at an AAS meeting and to the popular press the discovery of multiple planets in this system, detected by astrometry.

Based upon parallax measurements with the Hipparcos astrometry satellite, Kapteyn's Star is from the Earth. It came within of the Sun about 10,800 years ago and has been moving away since that time. The star is between one quarter and one third the size and mass of the Sun and has a much cooler effective temperature at about 3500 K, with some disagreement in the exact measurements between different observers. The stellar classification is sdM1, which indicates that it is a subdwarf with a luminosity lower than that of a main-sequence star at the same spectral type of M1.

Hipparcos was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky. This permitted the first high-precision measurements of the intrinsic brightnesses (compared to the less precise apparent brightness), proper motions and parallaxes of stars, enabling better calculations of their distance and tangential velocity. When combined with radial velocity measurements from spectroscopy, astrophysicists were able to finally measure all six quantities needed to determine the motion of stars.

More recently George Gatewood began using the Allegheny Observatory to search for extrasolar planets as well as to follow up on claims of extrasolar planets, starting in 1972. This is done using astrometry, which is the practice of measuring the position of stars. In addition to studying the positions of stars on the thousands of photographic plates in the vaults of the observatory, George Gatewood also designed the Multichannel Astrometric Photometer (MAP) for use with the Thaw telescope to measure the position of a target star and its close neighbors on images taken 6 months apart. This technique takes advantage of parallax.

The parallax of the two brightest stars were measured as part of the Hipparcos astrometry mission. This yielded a parallax of 47.44 milliarcseconds for 16 Cygni A and 47.14 milliarcseconds for 16 Cygni B. Since the two components are associated, it is reasonable to assume they lie at the same distance, so the different parallaxes are a result of experimental error (indeed, when the associated parallax errors are taken into account, the ranges of the parallaxes overlap). Using the parallax of the A component, the distance is 21.1 parsecs. The parallax of the B component corresponds to a distance of 21.2 parsecs.

Bengt was discovered on 24 September 1960, by Dutch astronomer couple Ingrid and Cornelis van Houten in collaboration with Tom Gehrels, who took the photographic plates at Palomar Observatory in California. The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out. The trio are credited with several thousand asteroid discoveries.

The car was observed by the Deimos Sky Survey (DeSS) at a distance of with a flashing effect suggesting spinning. Through measuring changes in apparent brightness of the object, astronomers have determined that the Roadster is rotating with a period of 4.7589 ± 0.0060 minutes (i.e. 4 minutes, 46 seconds). By February 11, 2018, astrometry measurements from 241 independent observations had been collated, refining the positions to within one-tenth of an arcsecond and published by the SeeSat-L mailing list, a group of amateur satellite spotters—more accurate than for most observations of objects in space.

The publication of the shape model and of astrometry based on radar observations obtained in 1999, 2005, and 2011, made possible an improved estimate of the Yarkovsky acceleration and a revised assessment of the impact probability. The best estimate of the impact probability is a cumulative probability of 0.037% in the interval 2175 to 2196. This corresponds to a cumulative score on the Palermo scale of −1.71. If an impact were to occur, the expected kinetic energy associated with the collision would be 1,200 megatons in TNT equivalent (for comparison, TNT equivalent of Little Boy was approx 15 kiloton).

The Astronomisches Rechen-Institut The Astromomisches Rechen-Institut (Astronomical Calculation Institute) is part of the Center of Astronomy of the University of Heidelberg. Before it was a research institute for astrometry and stellar dynamics belonging to the state of Baden-Württemberg. It is the most important international institution for astronomical data calculations. The Astronomisches Rechen-Institut is responsible among other things for the Gliese catalog of nearby stars, the fundamental catalog FK5 and FK6 and the annual published Apparent places, a high precision catalog with pre-calculated positions for over 3 thousand stars for each day.

The Gaia astrometry mission was launched as one of three missions in the Horizon 2000 Plus campaign. Horizon 2000 Plus was an extension of Horizon 2000 programme prepared in the mid-1990s, planning missions in the 1995–2015 timeframe. This included two further cornerstone missions, the star-mapping GAIA launched in 2013, and the BepiColombo mission to Mercury launched in 2018; and also a technology demonstrator LISA Pathfinder launched in 2015, to test technologies for the future LISA. All of the Horizon 2000 and Plus missions were successful, except for the first Cluster which was destroyed in 1996 when its launch rocket exploded.

Denebola , designated Beta Leonis (β Leonis, abbreviated Beta Leo, β Leo) is the second-brightest star in the zodiac constellation of Leo, although the two components of the γ Leonis double star, which are unresolved to the naked eye, have a combined magnitude brighter than it. Denebola is an A-type main sequence star with 75% more mass than the Sun and 15 times the Sun's luminosity. Based on parallax measurements from the Hipparcos astrometry satellite, the star is at a distance of about from the Sun. Its apparent visual magnitude is 2.14, making it readily visible to the naked eye.

Size comparison of Pollux (left) and The Sun (right) At an apparent visual magnitude of 1.14, Pollux is the brightest star in its constellation, even brighter than its neighbor Castor (α Geminorum). Pollux is 6.7 degrees north of the ecliptic, too far north to be occulted by the moon and planets, but in the distant future it will be close enough. Parallax measurements by the Hipparcos astrometry satellite place Pollux at a distance of about from the Sun. The star is larger than the Sun, with about two times its mass and almost nine times its radius.

The Palomar Testbed Interferometer (PTI) was a near infrared, long-baseline stellar interferometer located at Palomar Observatory in north San Diego County, California, United States. It was built by Caltech and the Jet Propulsion Laboratory and was intended to serve as a testbed for developing interferometric techniques to be used at the Keck Interferometer. It began operations in 1995 and achieved routine operations in 1998, producing more than 50 refereed papers in a variety of scientific journals covering topics from high precision astrometry to stellar masses, stellar diameters and shapes. PTI concluded operations in 2008 and has since been dismantled.

As civilizations developed, most notably in Mesopotamia, Greece, Persia, India, China, Egypt, and Central America, astronomical observatories were assembled and ideas on the nature of the Universe began to develop. Most early astronomy consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon and the Earth in the Universe were explored philosophically. The Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it.

As part of the observatory's relocation from London to the clearer and darker skies of Sussex, Hunter moved in 1956 to the Royal Greenwich Observatory's new site at Herstmonceux Castle. His department was split into two by the new Astronomer Royal, Sir Richard Woolley, with Hunter becoming head of the Department of Astrometry. Hunter worked for six months at Mount Wilson Observatory in 1959–1960 to gain experience of using large telescopes, in preparation for the construction of a new telescope at Herstmonceux. Alan Hunter was promoted to be Chief Assistant in 1961, when he was responsible for the Royal Greenwich Observatory's administration.

Timothy David Puckett was born in 1962 in Atlanta, Georgia, USA, and is an amateur astronomer and astrophotographer with over 30 years experience. Experienced in the field of amateur CCD (digital) astro-imaging, Puckett has operated numerous CCD cameras since 1989. He has built several robotic telescopes and is currently operating an automated supernova search patrol and comet astrometry program which uses 60-cm and 35-cm telescopes. Puckett's photos of comets and deep-sky objects have been published in books and magazines in several countries, including Great Britain, Japan, Italy, Germany, Australia and South Africa.

Fomalhaut , designation Alpha Piscis Austrini (α Piscis Austrini, abbreviated Alpha PsA, α PsA) is the brightest star in the constellation of Piscis Austrinus, the "Southern Fish", and one of the brightest stars in the sky. It is a class A star on the main sequence approximately from the Sun as measured by the Hipparcos astrometry satellite. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It is classified as a Vega-like star that emits excess infrared radiation, indicating it is surrounded by a circumstellar disk.

They may also be detected by indirect techniques, such as spectroscopy (spectroscopic binaries) or astrometry (astrometric binaries). If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit each other; these pairs are called eclipsing binaries, or, together with other binaries that change brightness as they orbit, photometric binaries. If components in binary star systems are close enough they can gravitationally distort their mutual outer stellar atmospheres. In some cases, these close binary systems can exchange mass, which may bring their evolution to stages that single stars cannot attain.

Orion OB1 Association The kinematics of Betelgeuse are complex. The age of Class M supergiants with an initial mass of is roughly 10 million years. Starting from its present position and motion a projection back in time would place Betelgeuse around farther from the galactic plane—an implausible location, as there is no star formation region there. Moreover, Betelgeuse's projected pathway does not appear to intersect with the 25 Ori subassociation or the far younger Orion Nebula Cluster (ONC, also known as Ori OB1d), particularly since Very Long Baseline Array astrometry yields a distance from Betelgeuse to the ONC of between 389 and .

Preliminary astrometric measurements made by the Hipparcos satellite suggest that this planet has an orbital inclination of 155.3° with respect to plane of the sky, which would imply a true mass of 11.1 times that of Jupiter, close to the deuterium burning threshold that some astronomers use to define the distinction between a planet and a brown dwarf. However subsequent analysis suggests that the Hipparcos measurements were not precise enough to accurately determine the orbits, so the actual inclination and true mass of the planet remains unknown. Its inclination is being calculated via astrometry with Hubble. The astrometricians expect publication by mid-2009.

The first person to publish a star's parallax was Friedrich G. W. von Struve, when he announced a value of () for Vega. Friedrich Bessel was skeptical about Struve's data, and, when Bessel published a parallax of 0.314″ for the star system 61 Cygni, Struve revised his value for Vega's parallax to nearly double the original estimate. This change cast further doubt on Struve's data. Thus most astronomers at the time, including Struve, credited Bessel with the first published parallax result. However, Struve's initial result was actually close to the currently accepted value of 0.129″, as determined by the Hipparcos astrometry satellite.

Gamma Draconis (γ Draconis, abbreviated Gamma Dra, γ Dra), formally named Eltanin , is a star in the northern constellation of Draco. Contrary to its gamma-designation (historically third-ranked), it is the brightest star in Draco at magnitude 2.4, outshining Beta Draconis by nearly half a magnitude and Alpha Draconis by over a magnitude. Gamma Draconis is at a distance of from the Sun, as determined by parallax measurements from the Hipparcos astrometry satellite. In 1728, while unsuccessfully attempting to measure the parallax of this star, the English astronomer James Bradley discovered the aberration of light resulting from the movement of the Earth.

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 KSAR 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 1.3 m 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.

Liu Hui (c. 263), How to measure the height of a sea island. Illustration from an edition of 1726 Gemma Frisius's 1533 proposal to use triangulation for mapmaking Nineteenth-century triangulation network for the triangulation of Rhineland- Hesse Triangulation today is used for many purposes, including surveying, navigation, metrology, astrometry, binocular vision, model rocketry and gun direction of weapons. In the field, triangulation methods were apparently not used by the Roman specialist land surveyors, the agromensores; but were introduced into medieval Spain through Arabic treatises on the astrolabe, such as that by Ibn al-Saffar (d. 1035).

James Dunlop FRSE (31 October 1793 – 22 September 1848) was a Scottish astronomer, noted for his work in Australia. He served as astronomer's assistant who was hired by Sir Thomas Brisbane to work at his private observatory, once located at Paramatta (now named Parramatta), New South Wales, about west of Sydney during the 1820s and 1830s. Dunlop was mostly a visual observer, doing stellar astrometry work for Brisbane, and after its completion, then independently discovered and catalogued many new telescopic southern double stars and deep-sky objects. He later became the Superintendent of Paramatta Observatory when it was finally sold to the New South Wales Government.

The first natural satellite discovered using photographic plates was Phoebe in 1898. Pluto was discovered using photographic plates in a blink comparator; its moon Charon was discovered 48 years later in 1978 by U.S. Naval Observatory astronomer James W. Christy by carefully examining a bulge in Pluto's image on a photographic plate. Glass- backed plates, rather than film, were generally used in astronomy because they do not shrink or deform noticeably in the development process or under environmental changes. Several important applications of astrophotography, including astronomical spectroscopy and astrometry, continued using plates until digital imaging improved to the point where it could outmatch photographic results.

It began publication in 1776 and continued until 1960 when it was merged into the international edition of the Astronomical Ephemeris and Apparent Places of Fundamental Stars (APFS). This merger was decided in 1959 by the IAU. Starting in 1907 it contained accurate apparent places of the first international fundamental catalogue which was compiled for astrometry; later these data were actualized within the framework of the Catalogues of Fundamental Stars FK3 and FK4. In the 1940s the Almanac was edited in co-operation with the Astronomisch-Geodätisches Jahrbuch of the Recheninstitut in Heidelberg, Germany, which was also merged into the IAU editions like other national almanacs.

Triangulation today is used for many purposes, including surveying, navigation, metrology, astrometry, binocular vision, model rocketry and, in the military, the gun direction, the trajectory and distribution of fire power of weapons. The use of triangles to estimate distances dates to antiquity. In the 6th century BC, about 250 years prior to the establishment of the Ptolemaic dynasty, the Greek philosopher Thales is recorded as using similar triangles to estimate the height of the pyramids of ancient Egypt. He measured the length of the pyramids' shadows and that of his own at the same moment, and compared the ratios to his height (intercept theorem).

A large fork mounted telescope and several other amateur built telescopes on display at Stellafane The telescopes amateur telescope makers build range from backyard variety to sophisticated instruments that make meaningful contributions to the field of astronomy. Instruments built by amateurs have been employed in planetary study, astrometry, photometry, comet and asteroid discovery to name just a few. Even the “hobbyist” end of the field can break down into several distinct categories such as: observing deep sky objects, observing the planets, solar observing, lunar observation, and astrophotography of all those classes of objects. Therefore, the design, size, and construction of the telescopes vary as well.

Gehrels was discovered during the Palomar–Leiden survey by the Dutch astronomer couple Ingrid and Cornelis van Houten, in collaboration with Dutch–American astronomer Tom Gehrels at Palomar Observatory, California, on 24 September 1960. The survey designation "P-L" stands for Palomar–Leiden, named after Palomar and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory, where astrometry was carried out. The trio are credited with the discovery of several thousand minor planets.

Horus was discovered on 24 September 1960, by Cornelis Johannes van Houten and Ingrid van Houten-Groeneveld at Leiden, on photographic plates taken by Tom Gehrels at Palomar. On the same date, the trio of astronomers also discovered 1912 Anubis, 1923 Osiris and 5011 Ptah. The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out.

On 19 May 1999, Lindegren was awarded the ESA's Director of Science Medal for his extraordinary efforts in ESA's scientific missions. At a ceremony in Bern, Switzerland, the first four medals were presented to scientific consortia leaders of the Hipparcos mission, Catherine Turon and Jean Kovalevsky from France, Lennart Lindegren from Sweden and Erik Høg from Denmark.ESA's Director of Science Medal In 2009, Lindegren was elected as a member of the Royal Swedish Academy of Sciences.KVA Members of Royal Swedish Academy of Sciences In 2011, he was awarded an Honorary Doctorate by the Paris Observatory, in recognition of his fundamental contributions to space astrometry over more than 30 years.

Altdorfer was discovered on 24 September 1960, by Dutch astronomer couple Ingrid and Cornelis van Houten at Leiden, on photographic plates taken by Dutch–American astronomer Tom Gehrels at Palomar Observatory in California, United States. No precoveries were taken, and no identifications were made prior to its official discovery observation. The survey designation "P-L" stands for Palomar–Leiden, named after the fruitful Palomar–Leiden survey, a collaboration between the Palomar and Leiden Observatory in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out.

The probability Ptarget for a capsule to hit the target area with radius rtarget (m) is the given by the ratio of the targeting scatter and the target area. :Ptarget = Atarget/π(δy)2 = 4.4×1025 rtarget2v2/(αp2d4) To apply these equations, the precision of astrometry of star proper motion of 0.00001 arcsec/year, and the solar sail vehicle velocity of 0.0005 c (1.5 × 105 m/s) may be expected within a few decades. For a chosen planetary system, the area Atarget may be the width of the habitable zone, while for interstellar clouds, it may be the sizes of the various density zones of the cloud.

HD 43587, being a bright, nearby, high proper motion solar-type star, has been fairly extensively studied. The star was found to be slightly hotter than the Sun, but has a similar metallicity and is therefore not much more massive. Searches for companions to the star, among many other stars, were ongoing throughout the last century. HD 43587 did not seem to have a variable radial velocity or much variability in its astrometry which would indicate that it had a close companion. The Washington Double Star Catalog lists four visual companions; companion B, discovered in 1891, has differing proper motion to the primary, so it is unrelated.

Additional precovery astrometry from the Sloan Digital Sky Survey and the Pan-STARRS1 survey shows that is a resonant trans-Neptunian object, securely trapped in a 2:9 mean motion resonance with Neptune, meaning that this minor planet orbits the Sun twice in the same amount of time it takes Neptune to complete 9 orbits. The object is unlikely to have been trapped in the 2:9 resonance for the age of Solar System. It is much more likely that it has been hopping between various resonances and got trapped in the 2:9 resonance in the last 100 million years. Distribution of trans- Neptunian objects.

Tiziano was discovered on 24 September 1960, by Dutch astronomer couple Ingrid and Cornelis van Houten, as well as Dutch–American astronomer Tom Gehrels. The asteroid was spotted during the Palomar–Leiden survey by examining photographic plates taken at Palomar Observatory, California, United States. The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out.

During the Great Patriotic War from August 1941 to March 1944 the observatory was occupied by the Germans. Director L.I. Semenov managed to keep it from serious injury and destruction. In the postwar period Jakov E. Gordon (1912–1978) was appointed to the post of director of the observatory (in 1951). In [1955], Repsold Meridian Circle was transported to Nikolaev from Pulkovo after reconstruction and a number of upgrades, on which different observational programs were carried out during 40 years. In 1961, Zonal Astrograph made by the “Carl Zeiss” firm was transferred from Pulkovo to NAO and the history of photographic astrometry has begun.

The planet was initially detected in data taken in 2012 at a separation from the parent star of (~56 AU) and position angle of . The planet was recovered at a high signal-to-noise ratio in June 2013. Astrometry for the planet in January 2012 and June 2013, and from a marginal detection in March 2013 confirm that it is bound to the parent star, not a background star. HD 95086 b's brightness at 3.8 μm when combined with sensitive upper limits on its brightness at shorter wavelengths is consistent with trends seen for other young, directly imaged planets like those around HR 8799.

Bertini got the Master degree in Astronomy at the University of Padua in 2001, discussing a thesis about the discovery, astrometry, and Photometry of asteroids with the Wide Angle Camera of the OSIRIS two-camera system instrument on board the European Space Agency's Rosetta mission. He obtained the PhD title of Doctor in Space Science and Technologies at the University of Padua in 2005. The thesis regarded "A new model of cometary dust and the Wide Angle Camera of the Rosetta Mission". After post-docs in Switzerland, Spain, and Italy, he is now working at the Center of Studies and Activities for Space (CISAS) 'G.

It took little time for Candy to position the Perth Observatory at the forefront of southern cometary astrometry. By 1972, the Perth Observatory was 9th in the world in producing cometary positions. Not content with this, Candy introduced new photographic glass plate processing practices to increase the limiting magnitude of objects achievable at that time from 14th to 19th. The new processes were to see the recovery of five comets and the positioning of the Observatory to 2nd place between 1973 and 1977 and 4th between 1978 and 1984, resulting in him being awarded the prestigious Merlin Medal of the British Astronomical Association in 1975.

For imaging observations, the SDSS telescope used the drift scanning technique, which tracks the telescope along a great circle on the sky and continuously records small strips of the sky. The image of the stars in the focal plane drifts along the CCD chip, and the charge is electronically shifted along the detectors at exactly the same rate, instead of staying fixed as in tracked telescopes. (Simply parking the telescope as the sky moves is only workable on the celestial equator, since stars at different declination move at different apparent speed). This method allows consistent astrometry over the widest possible field, and minimises overheads from reading out the detectors.

Gaia is a space observatory of the European Space Agency (ESA), launched in 2013 and expected to operate until 2022. The spacecraft is designed for astrometry: measuring the positions, distances and motions of stars with unprecedented precision. The mission aims to construct by far the largest and most precise 3D space catalog ever made, totalling approximately 1 billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars among others. The spacecraft will monitor each of its target objects about 70 times over the first five years of the mission to study the precise position and motion of each target, and will keep doing so.

The European VLBI Network (EVN) is a network of radio telescopes located primarily in Europe and Asia, with additional antennas in South Africa and Puerto Rico, which performs very high angular resolution observations of cosmic radio sources using very-long-baseline interferometry (VLBI). The EVN is the most sensitive VLBI array in the world, and the only one capable of real-time observations. The Joint Institute for VLBI ERIC (JIVE) acts as the central organisation in the EVN, providing both scientific user support and a correlator facility. Very Long Baseline Interferometry (VLBI) achieves ultra- high angular resolution and is a multi-disciplinary technique used in astronomy, geodesy and astrometry.

Gamma Ursae Majoris (γ Ursae Majoris, abbreviated Gamma UMa, γ UMa), formally named Phecda , is a star in the constellation of Ursa Major. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Based upon parallax measurements with the Hipparcos astrometry satellite, it is located at distance of around from the Sun. It is more familiar to most observers in the northern hemisphere as the lower-left star forming the bowl of the Big Dipper, together with Alpha Ursae Majoris (Dubhe, upper-right), Beta Ursae Majoris (Merak, lower-right) and Delta Ursae Majoris (Megrez, upper-left).

Because the Ogasawara Islands have never been connected to a continent, many of their animals and plants have undergone unique evolutionary processes. This has led to the islands' nickname of "The Galápagos of the Orient", and their nomination as a natural World Heritage Site on June 24, 2011. The giant squid (genus Architeuthis) was photographed off the Ogasawara Islands for the first time in the wild on 30 September 2004, and was filmed alive in December 2006. A radio telescope is located in Chichijima, one of the stations of the very-long-baseline interferometry (VLBI) Exploration of Radio Astrometry (VERA) project, and is operated by the National Astronomical Observatory of Japan.

Van de Kamp returned to McCormick on October 1, 1925 to take up the position left vacant by Harold Alden, who had just taken up the directorship of the Yale University Observatory Southern Station in Johannesburg, South Africa. In the spring of 1937, Van de Kamp left McCormick Observatory to take over as director of Swarthmore College's Sproul Observatory. One of his early pupils in astrometry was Nancy Grace Roman, who went on to become NASA's first Chief of Astronomy.url= Interview of Nancy G. Roman by David DeVorkin on 1980 August 19, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.

Wiles was discovered on 29 September 1973, by Dutch astronomer couple Ingrid and Cornelis van Houten at Leiden and Tom Gehrels at Palomar Observatory, California, United States. The body's observation arc begins at Palomar, 10 days prior to its official discovery observation. The survey designation "T-2" stands for the second Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out.

Boss was born in Albany, New York to astronomer Lewis Boss and Helen M. (Hutchinson) Boss. After attending The Albany Academy, he graduated from Harvard University in 1901 and worked at Dudley Observatory until 1905. Following a year at the U. S. Naval Observatory in Washington, D.C., he became director of the U.S. Naval Observatory at Samoa and helped organized the expedition to Flint Island to observe the 1908 solar eclipse. He served as director from 1906-1908. He joined the Department of Meridian Astrometry of the Carnegie Institution of Washington in 1908, working as a secretary until 1912 when he became acting director.

Four first magnitude stars, Regulus, Spica, Antares, and Aldebaran, are sufficiently close to the ecliptic that they may be occulted by the Moon. In addition, two star clusters visible to the naked eye, the Beehive Cluster and the Pleiades, are often occulted. Depending on one's location on the Earth, there are usually several occultations involving naked eye objects every year and many more that can be observed using binoculars or a telescope. Accurate timings (accuracy at least +/-0.02 seconds) of lunar occultations are scientifically useful in fields such as lunar topography, astrometry, and binary star studies and are collected by the International Occultation Timing Association - IOTA.

In astrometry, an International Celestial Reference Frame (ICRF) is a realization of the International Celestial Reference System (ICRS) using reference celestial sources observed at radio wavelengths. In the context of the ICRS, a reference frame is the physical realization of a reference system, i.e., the reference frame is the set of reported coordinates of the reference sources, with the coordinates derived using the procedures spelled out by the ICRS. The ICRF creates a quasi-inertial frame of reference centered at the barycenter of the Solar System, whose axes are defined by the measured positions of extragalactic sources (mainly quasars) observed using very long baseline interferometry.

Optical interferometers are extremely complex, unfilled aperture photon-collecting telescopes in the visual (sometimes the near infrared, too), which produce synthesized images and fringe data "on the fly" (unlike radio interferometers which are privileged to record the data for later synthesis), essentially by taking an inverse Fourier transform of the incoming data. Astrometry is understood by precisely measuring delay line additions while fringing, to match the light path differences from baseline ends. Using essentially trigonometry the angle and position of where the array is 'pointed' can be determined, thus inferring a precise position on the sphere of the sky. Only a few exist that can be considered operational.

Among his notable contributions to astronomy was the design of the impersonal (prismatic) astrolabe now known as the Danjon astrolabe, which led to an improvement in the accuracy of fundamental optical astrometry. An account of this instrument, and of the results of some early years of its operation, are given in Danjon's 1958 George Darwin Lecture to the Royal Astronomical Society. He also developed the "Danjon limit", a proposed measure of the minimum angular separation between the Sun and the Moon at which a lunar crescent is visible. However, this limit may not exist. He was Director of the Observatory of Strasbourg from 1930 to 1945 and of the Paris Observatory from 1945 to 1963.

These images for the first time showed stars too faint to be seen by the human eye. UCO Lick Observatory page on the Crossley telescope The first all-sky photographic astrometry project, Astrographic Catalogue and Carte du Ciel, was started in 1887. It was conducted by 20 observatories all using special photographic telescopes with a uniform design called normal astrographs, all with an aperture of around and a focal length of , designed to create images with a uniform scale on the photographic plate of approximately 60 arcsecs/mm while covering a 2° × 2° field of view. The attempt was to accurately map the sky down to the 14th magnitude but it was never completed.

This system holds the current record for the widest range of masses in a single planetary system, and also shows a hierarchy reminiscent of the solar system, with the gas giants at large distances from the star while the smaller bodies are much closer-in. There are two Super-Jupiter planets: ‘b‘ with a period of 1052 days (2.9 years) and minimum mass of 6,7 MJ, and ‘c‘ with a period of 7340 days (20.1 years) and a mass of 6,8 MJ.The mass of planet GJ 676A b from ground- based astrometry? A planetary system with two mature gas giants suitable for direct imaging // Astronomy & Astrophysics manuscript no. 28854 August 3, 2016.

Anubis was discovered on 24 September 1960, by the Dutch and Dutch–American astronomers Ingrid and Cornelis van Houten at Leiden, and Tom Gehrels, who took the photographic plates at Palomar Observatory, California. On the same night, the trio of astronomers also discovered 1923 Osiris, 1924 Horus and 5011 Ptah, also named after Ancient Egyptian deities. The survey designation "P-L" stands for Palomar–Leiden, named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory where astrometry was carried out.

Albrecht was discovered on 25 March 1971, by Dutch astronomer couple Ingrid and Cornelis van Houten, on photographic plates taken by Dutch–American astronomer Tom Gehrels at the U.S. Palomar Observatory, California. The first precovery was taken at Palomar Observatory in 1953, extending the asteroid's observation arc by 18 years prior to its discovery. The special designation T-1 stands for the first Palomar–Leiden Trojan survey, named after the fruitful collaboration of the Palomar and Leiden Observatory in the 1960s and 1970s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Cornelis and Ingrid van Houten-Groeneveld at Leiden Observatory where astrometry was carried out.

Marsden was discovered on 24 March 1971, by Dutch astronomer couple Ingrid and Cornelis van Houten at Leiden, on photographic plates taken by Dutch–American astronomer Tom Gehrels at Palomar Observatory, California. The discovery was made in a survey of faint Trojans (in spite of not having received a typical T-1 designation). The trio of Dutch and Dutch–American astronomers collaborated on the productive Palomar–Leiden survey in the 1960s, using the same procedure as for this smaller Trojan campaign: Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Cornelis and Ingrid van Houten at Leiden Observatory where blinking and astrometry was carried out.

At that time, the 85-2 telescope was placed at the end of the track and cables were connected between the two telescopes. The GBI began operation that year as a two element interferometer in order to test large aperture synthesis arrays and study radio astrometry and interstellar scintillation. 85-3 movable telescope with truck tires to allow it to move along the track In 1967 the array was upgraded with construction of the third element (85-3) to be located in the middle of the track. Both 85-2 and 85-3 had truck tires mounted on either side to allow them to be moved along the track to test different baselines.

Gurshtein attended Moscow State Institute of Geodesy and Cartography, and graduated with a degree in astrometry in 1959. Following his graduation, he worked at the Russian Academy of Sciences and in the Soviet Space program during the Space Race of the Cold War. Gurshtein earned his Candidate of Science from Sternberg State Astronomical Institute, Moscow in 1966 and a Doctor of Science degree in Physics & Mathematics from Pulkovo Astronomical Observatory in Saint Petersburg in 1980. Gurshtein was active as an astronomer in the space program and held a number of offices in professional organizations, including Head of Council for Astronomical Education and Vice Director of the Institute for History of Science & Technology, both for the Russian Ministry of Education.

Because Polaris lies nearly in a direct line with the Earth's rotational axis "above" the North Pole—the north celestial pole—Polaris stands almost motionless in the sky, and all the stars of the northern sky appear to rotate around it. Therefore, it makes an excellent fixed point from which to draw measurements for celestial navigation and for astrometry. The moving of Polaris towards and, in the future, away from the celestial pole, is due to the precession of the equinoxes. The celestial pole will move away from α UMi after the 21st century, passing close by Gamma Cephei by about the 41st century, moving towards Deneb by about the 91st century.

The Gaia payload consists of three main instruments: # The astrometry instrument (Astro) precisely determines the positions of all stars brighter than magnitude 20 by measuring their angular position. By combining the measurements of any given star over the five-year mission, it will be possible to determine its parallax, and therefore its distance, and its proper motion—the velocity of the star projected on the plane of the sky. # The photometric instrument (BP/RP) allows the acquisition of luminosity measurements of stars over the 320–1000 nm spectral band, of all stars brighter than magnitude 20. The blue and red photometers (BP/RP) are used to determine stellar properties such as temperature, mass, age and elemental composition.

Since this time, many more double stars have been catalogued and measured. The Washington Double Star Catalog, a database of visual double stars compiled by the United States Naval Observatory, contains over 100,000 pairs of double stars,"Introduction and Growth of the WDS", The Washington Double Star Catalog , Brian D. Mason, Gary L. Wycoff, and William I. Hartkopf, Astrometry Department, United States Naval Observatory, accessed on line August 20, 2008. including optical doubles as well as binary stars. Orbits are known for only a few thousand of these double stars,Sixth Catalog of Orbits of Visual Binary Stars , William I. Hartkopf and Brian D. Mason, United States Naval Observatory, accessed on line August 20, 2008.

However, in 1918 the Dutch-American astronomer Adriaan van Maanen was able to measure the proper motion of stars in part of the Pleiades cluster by comparing photographic plates taken at different times. As astrometry became more accurate, cluster stars were found to share a common proper motion through space. By comparing the photographic plates of the Pleiades cluster taken in 1918 with images taken in 1943, van Maanen was able to identify those stars that had a proper motion similar to the mean motion of the cluster, and were therefore more likely to be members. Spectroscopic measurements revealed common radial velocities, thus showing that the clusters consist of stars bound together as a group.

The KSAR Telescope's 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 , 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 milliarcsecond level, and close-separation, PSF photometry.

To date NPOI has produced the highest resolution optical images of any astronomical instrument, though this may change when the CHARA array and Magdalena Ridge Observatory Interferometer begin optical-band operations. The first astronomical object imaged (resolved) by NPOI was Mizar, and since, a significant amount of astrometry, reference tie frame, rapid rotator star, and Be stellar disk study has been performed. NPOI is capable of determining positions of celestial objects to a few milli- arcsecond, in part due to the optical anchoring of its components using a complex metrology array of lasers that connect main optical elements to each other and to bedrock. Many specialized lasers are also used to align the long train of optics.

The Gaia Data Processing and Analysis Consortium (DPAC) is a group of over 400 European scientists and software engineers formed with the objective to design, develop and execute the data processing system for ESA's ambitious Gaia space astrometry mission. It was formally formed in June 2006 by European scientists, with the initial goal of answering an Announcement of Opportunity to be issued by ESA before the end of that year. At a meeting in Paris on 24–25 May 2007, ESA's Science Programme Committee (SPC) approved the DPAC proposal submitted in response to the Announcement of Opportunity for the Gaia data processing. The proposal describes a complete data processing system capable of handling the full size and complexity of the Gaia data within the mission schedule.

The European Space Agency (ESA) was established in May 1975 as the merger of the European Space Research Organisation (ESRO) and the European Launcher Development Organisation. In 1970, the governing Launch Programme Advisory Committee (LPAC) of ESRO made a decision not to execute astronomy or planetary missions, which were perceived as beyond the budget and capabilities of the organisation at the time. This meant that cooperation with other government space agencies and institutions was necessary for large-scale scientific missions. This policy was effectively reversed in 1980, when ESA's then-Director of Science, Ernst Trendelenburg, and the agency's new authoritative Science Programme Committee (SPC) selected the Giotto flyby reconnaissance mission to comet Halley and the Hipparcos astrometry mission for launch.

In the past, time was measured by observing stars with instruments such as photographic zenith tubes and Danjon astrolabes, and the passage of stars across defined lines would be timed with the observatory clock. Then, using the right ascension of the stars from a star catalog, the time when the star should have passed through the meridian of the observatory was computed, and a correction to the time kept by the observatory clock was computed. Sidereal time was defined such that the March equinox would transit the meridian of the observatory at 0 hours local sidereal time. Beginning in the 1970s the radio astronomy methods very long baseline interferometry (VLBI) and pulsar timing overtook optical instruments for the most precise astrometry.

Based on parallax measurements from the Hipparcos astrometry satellite, this star is located about from the Earth. It has an apparent visual magnitude of 2.84 and a stellar classification of G5 II. The mass of this star is 3.5 times the mass of the Sun and it is about 240 million years old, which is sufficient time for a star this massive to consume the hydrogen at its core and evolve away from the main sequence, becoming a G-type bright giant. This is a double star system and may be a binary. Using adaptive optics on the AEOS telescope at Haleakala Observatory, the pair was found to be separated by an angle of 2.58 arcseconds at a position angle of 1.4°.

Piet van de Kamp (December 26, 1901 in KampenLaurence W. Fredrick, Peter van de Kamp (1901–1995), Publications of the Astronomical Socitiey of the Pacific 108:556–559, July 1996 – May 18, 1995 in Amsterdam), known as Peter van de Kamp in the United States, was a Dutch astronomer who lived in the United States most of his life. He was professor of astronomy at Swarthmore College and director of the college's Sproul Observatory from 1937 until 1972. He specialized in astrometry, studying parallax and proper motions of stars. He came to public attention in the 1960s when he announced that Barnard's star had a planetary system based on observed "wobbles" in of its motion, but this is now known to be false.

Satellite watching started by being done with the naked eye or with the aid of binoculars since predictions of when they would be visible was difficult; most low Earth orbit satellites also move too quickly to be tracked easily by the telescopes available to astronomers. It is this movement, as the satellite tracks across the night sky, that makes them possible to see. As with any sky-watching pastime, the darker the sky the better, so hobbyists will meet with better success further away from light-polluted urban areas. Today most observers use digital still cameras or video cameras; imagery is put into Astrometry software to generate the angles needed to generate "observations" that are used to calculate orbits of the satellites imaged.

The Naval Meteorology and Oceanography Command (COMNAVMETOCCOM) or CNMOC, serves as the operational arm of the Naval Oceanography Program. Headquartered at the Stennis Space Center in Mississippi, CNMOC is an echelon three command reporting to United States Fleet Forces Command (USFLTFORCOM). CNMOC's claimancy is globally distributed, with assets located on larger ships (aircraft carriers, amphibious ships, and command and control ships), shore facilities at fleet concentration areas, and larger production centers in the U.S. CNMOC is focused on providing critical environmental knowledge to the warfighting disciplines of Anti-Submarine Warfare; Naval Special Warfare; Mine Warfare; Intelligence, Surveillance and Reconnaissance; and Fleet Operations (Strike and Expeditionary), as well as to the support areas of Maritime Operations, Aviation Operations, Navigation, Precise Time, and Astrometry. Oceanographer of the Navy seal.

It was originally installed at the Observatoire de Paris in 1872. It is now equipped with a direct CCD camera at the f/6 Newton focus and is mainly used for studies of variability of X-ray sources, imaging of galaxies and H II regions and astrometry of faint solar system objects. The 0.80 m telescope was first used during site testing at nearby Forcalquier in 1932 before the construction of the observatory, where it was later moved in 1945. The telescope is equipped with CCD cameras allowing high quality observations to be made using it, but unlike the other telescopes on site which have computer-controlled pointing systems, the 0.80 m telescope must still be pointed manually, using setting circles.

The combination of the large detector array and the short and frequent exposures necessary at infrared wavelengths results in a high data rate of 200–300 GB per night. A quick-look reduction at the Paranal Observatory will be used for daily quality control, but the principal data flow is to transfer the raw data to ESO headquarters in Garching near Munich, Germany, for ingestion into the data archive. Users can extract paw prints (see above) and pass them through a calibration pipeline to remove instrumental artefacts and calibrate the astrometry and photometry. The archive data will also be copied to the VISTA Data Flow System in the UK, where the paw prints will be combined into tiles (see above) and where source catalogues will be prepared from these.

Achernar is the primary (or 'A') component of the binary system designated Alpha Eridani (α Eridani, abbreviated Alpha Eri, α Eri), which is the brightest star in the constellation of Eridanus, and the ninth-brightest in the night sky. The two components are designated Alpha Eridani A (the primary) and B (the secondary, also known informally as Achernar B). As determined by the Hipparcos astrometry satellite, it is approximately from the Sun. Of the ten apparent brightest stars in the night-time sky, Alpha Eridani is the hottest and bluest in color, due to Achernar being of spectral type B. Achernar has an unusually rapid rotational velocity, causing it to become oblate in shape. The secondary is smaller, of spectral type A, and orbits Achernar at a distance of roughly 12 astronomical units (AU).

An early accomplishment of Edmondson's was the creation of the Indiana Asteroid Program, a photographic program to locate asteroids that were "lost" when systematic observations were interrupted by World War II. He also negotiated the donation of the privately owned Goethe Link Observatory near Brooklyn, Indiana to Indiana University. Nearly 7000 photographic plates for asteroid orbit studies were taken with a 10-inch astrographic camera at the Goethe Link Observatory. These plates are now archived at Lowell Observatory. In addition to pursuing studies in stellar kinematics, galactic structure, asteroid astrometry and the history of astronomy, Edmondson served as Program Director for Astronomy of the National Science Foundation (1956–1957), treasurer of the American Astronomical Society (1954–1975) and statistical advisor to Dr. Alfred Kinsey during his studies of human sexuality.

Harris was successful in increasing the technical and astronomical staff numbers at the new Bickley Perth Observatory as its role moved to that of more of a scientific function, however Harris also restarted the public tours on 23 October 1966 and maintained the provision of information services to Western Australia. Harris also continued time and tide services for Western Australia, however as had been the case in 1908 for Meteorology, the move saw seismic monitoring activities being relocated to Mundaring under the Commonwealth Government control. Harris was responsible for the August 1973 IAU Symposium No. 61 in Perth on "New Problems of Astrometry". Like his predecessor, he died at an early age, 49, but had raised the standing of the Perth Observatory to a well respected scientific institution within Australia and internationally.

Procyon is the brightest star in the constellation of Canis Minor and usually the eighth-brightest star in the night sky, with a visual apparent magnitude of 0.34. It has the Bayer designation α Canis Minoris, which is Latinised to Alpha Canis Minoris, and abbreviated α CMi or Alpha CMi, respectively. As determined by the European Space Agency Hipparcos astrometry satellite, this system lies at a distance of just , and is therefore one of Earth's nearest stellar neighbours. A binary star system, Procyon consists of a white-hued main-sequence star of spectral type F5 IV–V, designated component A, in orbit with a faint white dwarf companion of spectral type DQZ, named Procyon B. The pair orbit each other with a period of 40.8 years and an eccentricity of 0.4.

In combination with other improvements such as narrow-pass filters and improved eyepieces, the large apertures of the Dobsonian have dramatically increased the number of objects observed as well as the amount of detail in each object observed. Whereas the amateur astronomer of the 1970s and 1980s typically did not explore much beyond the Messier and brighter NGC objects; thanks in part to Dobsonians, the amateur astronomer of today can routinely observe dim objects listed in obscure catalogues, such as the IC, Abell, Perek Kohoutek, Minkowski, and others once considered the domain only of professional astronomers. The Dobsonian (mounted on an equatorial platform) has also opened up the field of high precision asteroid astrometry (and discovery) to the amateur wishing to contribute minor planet positions to the Minor Planet Center.

The smallest KBO yet detected at that time was discovered in 2009 by poring over data from the Hubble Space Telescope's fine guidance sensors. They detected a transit of an object against a distant star, which, based on the duration and amount of dimming, was calculated to be a KBO about in diameter. It has been suggested that the Kepler observatory may be able to detect objects in the Oort cloud by their occultation of background stars,DETECTABILITY OF OORT CLOUD OBJECTS USING KEPLER - 2009 and the Whipple proposal would also try to use this concept A Hubble FGS has also been used for astrometry, tracking the movement of different starts. This ability was used for exoplanet research, where the motion of the star caused by the movement of planets around it was detected.

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 NPOI, and it performs photometric operations support to astrometric studies (along with its newer siblings). The 40-inch telescope 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 NPOI 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.

47 Ursae Majoris (abbreviated 47 UMa), formally named Chalawan ,Thai Astronomical Society, Chalawan, Taphao Thong, Taphao Kaew – First Thai Exoworld Names is a yellow dwarf star approximately 46 light-years from Earth in the constellation of Ursa Major. , three extrasolar planets (designated 47 Ursae Majoris b, c and d; the first two later named Taphao Thong and Taphao Kaew) are believed to orbit the star. The star is located fairly close to the Solar System: according to astrometric measurements made by the Hipparcos astrometry satellite, it exhibits a parallax of 71.11 milliarcseconds, corresponding to a distance of 45.913 light-years. With an apparent magnitude of +5.03, it is visible to the naked eye and its absolute magnitude of +4.29 implies a visual luminosity around 60% greater than the Sun.

Glaukos was discovered on 24 March 1971, by Dutch astronomer couple Ingrid and Cornelis van Houten at Leiden, on photographic plates taken by astronomer Tom Gehrels at the Californian Palomar Observatory in California. The body's observation arc begins with a precovery of its first recorded observation at Palomar in November 1955, or more than 15 years prior to its official discovery observation. This discovery was made in the context of a larger survey of faint Trojans. The trio of Dutch and Dutch–American astronomers also collaborated on the productive Palomar–Leiden survey in the 1960s, using the same procedure as for this (smaller) survey: Tom Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Cornelis and Ingrid van Houten at Leiden Observatory where astrometry was carried out.

Notable results were included in "A General Catalogue of Photoelectric Magnitudes and Colours in the UBV System of 3578 Galaxies, Brighter than the 16-th V Magnitude (1936-1982)" by G. Longo, Antoinette de Vaucouleurs and H.G. Corwin (1983) (see also Gérard de Vaucouleurs), with significant part of its data obtained from Belogradchik observatory. During the 1990s, beside fast stellar electro-photometry of variable stars, it was also a base for meticulous observations of minor bodies of the Solar System, including the famous Shoemaker-Levy 9 comet encounter with Jupiter in July 1994. In recent years Romanian astronomers have jointly used the observatory for an astrometry project, linked to the Gaia programme, prior to its launch in December 2013. It was by that time an automatic seismograph was mounted in an adjacent isolated compartment, where it serves both Romanian and Bulgarian seismologists.

The barycentric celestial reference system (BCRS) is a coordinate system used in astrometry to specify the location and motions of astronomical objects. It was created in 2000 by the International Astronomical Union (IAU) to be the global standard reference system for objects located outside the gravitational vicinity of Earth: planets, moons, and other Solar System bodies, stars and other objects in the Milky Way galaxy, and extra-galactic objects. The geocentric celestial reference system (GCRS), also created by the IAU in 2000, is a similar standard coordinate system used to specify the location and motions of near-Earth objects, such as satellites. These systems make it easier for scientists and engineers to compile, share, compare, and convert accurate measurements worldwide, by establishing standards both of measure and of methodology, and providing a consistent framework of operations.

As of May 2008, the facility is under a multi-year contract with NASA to provide follow-up astrometry and characterization data on near-Earth asteroids and comets as part of Spaceguard, and also collaborates with the Air Force to track and characterize satellites in GEO and LEO orbits. On October 9, 2009, New Mexico Tech scientists used instruments on the MRO 2.4-meter and at the Etscorn Campus Observatory to observe controlled impacts of two NASA Centaur rockets at the southern polar region of the moon as part of the LCROSS Project. On October 23, 2015, it was announced that the MRO telescope will receive funding from the Federal Aviation Administration (FAA) in early 2016 to monitor the launch and re-entry of commercial space vehicles from Spaceport America.Grant from FAA in 2016 for 2.4-Meter.

The observatory is located in Ty Ty, Georgia, USA – well away from any city light pollution and is in an excellent location to perform the follow-up observations of Near-Earth objects and Potentially Hazardous Asteroids that are near the vicinity of Earth on a regular basis. Also performed in the observatory is an early evening sky survey (such as Palomar sky survey or NEAT – Near-Earth Asteroid Tracking) to search for new comets and/or other unknown objects low on the horizon that can be easily overlooked due to the position of the object. Most amateur discovered comets are found in this location. Future plans for the observatory include an amateur based asteroid study program that will allow the "amateur astrometrist" on-line access to observatory images and there they will be able to perform astrometry on all detected asteroids or comets.

This guiding is done through a second co-mounted telescope called a "guide scope" or via some type of "off-axis guider", a device with a prism or optical beam splitter that allows the observer to view the same image in the telescope that is taking the picture. Guiding was formerly done manually throughout the exposure with an observer standing at (or riding inside) the telescope making corrections to keep a cross hair on the guide star. Since the advent of computer-controlled systems, this is accomplished by an automated system in professional and even amateur equipment. Astronomical photography was one of the earliest types of scientific photography and almost from its inception it diversified into subdisciplines that each have a specific goal including star cartography, astrometry, stellar classification, photometry, spectroscopy, polarimetry, and the discovery of astronomical objects such as asteroids, meteors, comets, variable stars, novae, and even unknown planets.

Sir Frank Watson Dyson, Astronomer Royal The aim of the expeditions was to take advantage of the shielding effect of the Moon during a total solar eclipse, and to use astrometry to measure the positions of the stars in the sky around the Sun during the eclipse. These stars, not normally visible in the daytime due to the brightness of the Sun, would become visible during the moment of totality when the Moon covered the solar disc. A difference in the observed position of the stars during the eclipse, compared to their normal position at night, would indicate that the light from these stars had bent as it passed close to the Sun. Dyson, when planning the expedition in 1916, had chosen the 1919 eclipse because it would take place with the Sun in front of a bright group of stars called the Hyades.

The initial plans were formulated by scientists at NASA's Jet Propulsion Laboratory in California, where a Lead Center for western hemisphere observations was established with support from NASA; a corresponding Center for eastern hemisphere observations was funded by the Federal Republic of Germany at the Remeis Observatory (code 521) in Bamberg. An international Steering Group was established, and a set of Discipline Specialists was chosen to organize observing networks, coordinate their activity, and ultimately to collect and archive their data. This effort was endorsed by the International Astronomical Union in 1982, and cometary scientists were chosen as Discipline Specialists in the areas of Astrometry, Infrared Studies, Large Scale Phenomena, Near-Nucleus Studies, Photometry and Polarimetry, Radio Studies, Spectroscopy and Spectrophotometry, Meteor Studies, and Amateur Observations. The IHW also coordinated with the space missions to the comet, Giotto by the European Space Agency and Vega by the Soviet Union and collaborating countries.

However, analysis of Fomalhaut b's astrometry showed that the object has a high eccentricity (e = 0.8), its orbit (projected on the sky) crosses the plane of Fomalhaut's debris ring, and thus it is unlikely to be the object sculpting the debris ring's sharp inner edge. Fomalhaut b's high eccentricity may be evidence for a significant dynamical interaction with a hitherto unseen planet at a smaller orbital separation. Analyses of additional STIS data obtained in 2013 and 2014 argue that Fomalhaut b is fading and expanding in size, a behavior that may support the interpretation of Fomalhaut b as a collision between two asteroid-sized objects. The revival of the claim that Fomalhaut b is (possibly) a planet after it had been discounted led some to nickname the object a "zombie planet", although this is a non-technical term used in press material and does not appear in any peer-reviewed manuscript.

During the early studies of ESA's Hipparcos space astrometry mission, and while still a graduate student in 1976, he was `recruited' to the project by Erik Høg, and thereafter played a crucial role in various aspects of the mission definition and in the data analysis. He set out the overall principles of the astrometric data reduction aiming to combine and solve together the attitude, the system and the astrometric parameters of the stars. This crucial `3-step procedure' was used successfully by the two consortia (NDAC and FAST) later entrusted by ESA with the Hipparcos data processing. The principle of reconstructing space astrometric positions from one-dimensional observations carried out in the innovative Hipparcos sky scanning mode was fully original (and frequently questioned outside the project), and at the very limit of available computational power even by the end of the mission in 1997. The numerical principles had to be demonstrated, together with the solution’s statistical properties.

Timely, meticulous, rigorous, and often the final word on a given topic, they have been of immense value to the development and definition of these two projects. In addition to the mathematical principles they frequently include working algorithms (often with source code when relevant). Amongst them are, for Hipparcos, the three-step astrometric reduction, optimization of the scanning law, notes on the imaging properties used for the multiple star analysis, assessment of chromatic effects, attitude developments, and many others. For Gaia, his technical notes cover the mathematical and statistical aspects of the Gaia instrument and processing (including the attitude determination and its mathematical representation with quaternions and splines), the modelling of the point/line spread functions, the CCD geometric calibrations, broad band photometry design, maximum likelihood determination of the CCD image centroiding, differential equations and optimal properties of the scanning law, along with the subtle systematic effects in astrometry caused by instrumental misalignments.

The BNSC was the third largest financial contributor to the General Budget of the European Space Agency, contributing 17.4%, to its Science Programme and to its robotic exploration initiative the Aurora programme. Investments were also made in the ESA telecommunications programme 'ARTES' in order to develop payload technology used, for example, in the satellites of Inmarsat, the UK based mobile satellite operator. The BNSC partnership co-funded a private sector project led by Avanti Communications to build a satellite called HYLAS'Our satellite HYLAS' to provide broadband communications to rural and remote users. Current projects in the field of space science include LISA Pathfinder, for which UK industry is the prime contractor and UK universities are building major payload elements; the astrometry Gaia mission, for which UK industry is supplying the detectors, avionics, software and data processing electronics; and the James Webb Space Telescope, for which a UK consortium led by the UK Astronomy Technology Centre is building the European part of the Mid Infra Red Instrument (MIRI).

The companion b was confirmed to be a brown dwarf with the accurate mass measurement in 2020. Pi Mensae was ranked 100th on the list of top 100 target stars for the planned (but now canceled) Terrestrial Planet Finder mission to search for Earth-like planets. On September 16, 2018, a preprint was posted to arXiv detailing the discovery of a super-Earth on a 6.27-day orbit around the star, the first exoplanet detection by the Transiting Exoplanet Survey Satellite (TESS) submitted for publication.. This was confirmed two days latter by where the attention was called that the system is amenable for future planet atmospheric studies. In 2020, an analysis with Gaia DR2 and Hipparcos astrometry showed that planets b and c are located on orbits mutually inclined by 49°-131° (1 sigma), which causes planet c to not transit most of the time, and acquire large misalignments with its host star's spin axis.

From the center to outer edge of the FGS field of view is 14.1 arcminutesThis is a diagram of the field of view of each Hubble Space Telescope instrument, including the three FGS instruments (FGS field of view(s) highlighted in yellow) Here is a Hubble Fine Guidance Sensor;it was refurbished on Earth between servicing missions SM3A and SM4 A fine guidance sensors in space on STS Servicing Mission 2 in 1997 Fine Guidance Sensor (FGS) for the Hubble Space Telescope is a system of three instruments used for pointing the telescope in space, and also for astrometry and its related sciences. Each FGS uses a combination of optics and electronics to provide for pointing the telescope at a certain location in the sky. There are three Hubble FGS, and they have been upgraded over the lifetime of the telescope by manned Space Shuttle missions. The instruments can support pointing of 2 milli-arc seconds (units of degree).

Stars and Other Objects in the Second Data Release.The second data release (DR2), which occurred on 25 April 2018, is based on 22 months of observations made between 25 July 2014 and 23 May 2016. It includes positions, parallaxes and proper motions for about 1.3 billion stars and positions of an additional 300 million stars in the magnitude range g = 3–20, Comparison of Gaia–CRF2 with a preliminary version of the forthcoming ICRF3 shows a global agreement of 20 to 30 μas, although individual sources may differ by several mas. Since the data processing procedure links individual Gaia observations with particular sources on the sky, in some cases the association of observations with sources will be different in the second data release. Consequently, DR2 uses different source identification numbers than DR1. A number of issues have been identified with the DR2 data, including small systematic errors in astrometry and significant contamination of radial velocity values in crowded star fields, which may affect some one percent of the radial velocity values.

Taqi al-Din measured the right ascension of the stars at the Constantinople Observatory of Taqi ad-Din using the "observational clock" he invented. When telescopes became commonplace, setting circles sped measurements James Bradley first tried to measure stellar parallaxes in 1729. The stellar movement proved too insignificant for his telescope, but he instead discovered the aberration of light and the nutation of the Earth's axis. His cataloguing of 3222 stars was refined in 1807 by Friedrich Bessel, the father of modern astrometry. He made the first measurement of stellar parallax: 0.3 arcsec for the binary star 61 Cygni. Being very difficult to measure, only about 60 stellar parallaxes had been obtained by the end of the 19th century, mostly by use of the filar micrometer. Astrographs using astronomical photographic plates sped the process in the early 20th century. Automated plate-measuring machinesCERN paper on plate measuring machine USNO StarScan and more sophisticated computer technology of the 1960s allowed more efficient compilation of star catalogues. In the 1980s, charge-coupled devices (CCDs) replaced photographic plates and reduced optical uncertainties to one milliarcsecond.

While at Yerkes, her research focused on stellar spectroscopy, emphasizing F and G type stars and high velocity stars. Her work produced some of the most highly cited papers at that time, including, in 1950, three top-100 papers in a year with over 3,000 publications She was offered research positions at Wayne State University and the University of Southern California, but turned them down as she felt the institutions lacked sufficient astronomical instrumentation, an issue of great importance to her. She traveled to Argonne National Laboratory to use their new astrometry machine for measuring photographic plates, but was unable to convince Yerkes to acquire one; she also advocated for the purchase of a then-novel digital computer for data analysis in 1954, but was turned down by department chair Subrahmanyan Chandrasekhar as he saw computers as not being useful for this purpose. Roman eventually left her job at the university because of the paucity of tenured research positions available to women at the time; they had never had a woman on the academic staff.

Artist's impression of the surface of a super-Earth orbiting Barnard's Star For a decade from 1963 to about 1973, a substantial number of astronomers accepted a claim by Peter van de Kamp that he had detected, by using astrometry, a perturbation in the proper motion of Barnard's Star consistent with its having one or more planets comparable in mass with Jupiter. Van de Kamp had been observing the star from 1938, attempting, with colleagues at the Sproul Observatory at Swarthmore College, to find minuscule variations of one micrometre in its position on photographic plates consistent with orbital perturbations that would indicate a planetary companion; this involved as many as ten people averaging their results in looking at plates, to avoid systemic individual errors. Van de Kamp's initial suggestion was a planet having about at a distance of 4.4AU in a slightly eccentric orbit, and these measurements were apparently refined in a 1969 paper. Later that year, Van de Kamp suggested that there were two planets of 1.1 and .