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41-477: The observatory was opened in 1839. Originally, it was a brainchild of the German/Russian astronomer Friedrich Georg Wilhelm von Struve , who would become its first director (in 1861, his son Otto Wilhelm von Struve succeeded him). The architect was Alexander Bryullov . The observatory was equipped with state-of-the-art devices , one of them being the a 15-inch (380 mm) aperture refractor , one of

82-478: A common technique for astrometry. In the 1980s, charge-coupled devices (CCDs) replaced photographic plates and reduced optical uncertainties to one milliarcsecond. 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

123-404: A few hours a month to stargazing and reading the latest developments in research. However, amateurs span the range from so-called "armchair astronomers" to the highly ambitious people who own science-grade telescopes and instruments with which they are able to make their own discoveries, create astrophotographs , and assist professional astronomers in research. Astrometric Astrometry

164-438: A few weeks per year. Analysis of observed phenomena, along with making predictions as to the causes of what they observe, takes the majority of observational astronomers' time. Astronomers who serve as faculty spend much of their time teaching undergraduate and graduate classes. Most universities also have outreach programs, including public telescope time and sometimes planetariums , as a public service to encourage interest in

205-633: A former observatory of the Department of the Navy, (today's Nikolaev Astronomical Observatory). During the siege of Leningrad (1941–1944), the Observatory became the target of fierce German air raids and artillery bombardment . All of the buildings were completely destroyed. Under dramatic circumstances, the main instruments were saved and stored safely in Leningrad , including the lens of

246-573: 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. To find such objects astrometrically, astronomers use telescopes to survey the sky and large-area cameras to take pictures at various determined intervals. By studying these images, they can detect Solar System objects by their movements relative to

287-538: A precision of 15–35 arcsec . Ottoman scholar 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 English astronomer James Bradley first tried to measure stellar parallaxes in 1729. The stellar movement proved too insignificant for his telescope , but he instead discovered

328-738: A system of stars or a galaxy to complete a life cycle, astronomers must observe snapshots of different systems at unique points in their evolution to determine how they form, evolve, and die. They use this data to create models or simulations to theorize how different celestial objects work. Further subcategories under these two main branches of astronomy include planetary astronomy , astrobiology , stellar astronomy , astrometry , galactic astronomy , extragalactic astronomy , or physical cosmology . Astronomers can also specialize in certain specialties of observational astronomy, such as infrared astronomy , neutrino astronomy , x-ray astronomy , and gravitational-wave astronomy . Historically , astronomy

369-557: Is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies . It provides the kinematics and physical origin of the Solar System and this galaxy , the Milky Way . 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

410-405: 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

451-531: The Almagest , giving their location, coordinates, and brightness. In the 10th century, the Iranian astronomer Abd al-Rahman al-Sufi carried out observations on the stars and described their positions, magnitudes and star color ; furthermore, he provided drawings for each constellation, which are depicted in his Book of Fixed Stars . Egyptian mathematician Ibn Yunus observed more than 10,000 entries for

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492-689: The Palomar Observatory 's Samuel Oschin telescope of 48 inches (1.2 m) and the Palomar-Quest large-area CCD camera. The ability of astronomers to track the positions and movements of such celestial bodies is crucial to the understanding of the Solar System and its interrelated past, present, and future with others in the Universe. A fundamental aspect of astrometry is error correction. Various factors introduce errors into

533-576: The aberration of light and the nutation of the Earth's axis. His cataloguing of 3222 stars was refined in 1807 by German astronomer Friedrich Bessel , the father of modern astrometry. He made the first measurement of stellar parallax: 0.3 arcsec for the binary star 61 Cygni . In 1872, British astronomer William Huggins used spectroscopy to measure the radial velocity of several prominent stars, including Sirius . Being very difficult to measure, only about 60 stellar parallaxes had been obtained by

574-399: The ancient Greek astronomer 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. Hipparchus compiled a catalogue with at least 850 stars and their positions. Hipparchus's successor, Ptolemy , included a catalogue of 1,022 stars in his work

615-566: The arc of the meridian from the Danube to the Arctic Ocean (until 1851), and in triangulation of Spitsbergen in 1899–1901. Military geodesists and hydrographers used to work at the Observatory as interns. The Pulkovo Meridian, which passes through the center of the main building of the Observatory and is located at 30°19,6‘ east of Greenwich , was the point of departure for all former geographical maps of Russia. In order to observe

656-513: The geographical study of the territory of Russia and development of navigation . The star catalogues , containing the most precise positions of 374, and then 558 stars, were made for the years 1845, 1865, 1885, 1905 and 1930. By the 50th anniversary of the Observatory, they had built an astrophysical laboratory with a mechanical workshop and installed the Europe's largest refractor, (30 inch). Astrophysical research really gained momentum with

697-568: The origin or evolution of stars , or the formation of galaxies . A related but distinct subject is physical cosmology , which studies the Universe as a whole. Astronomers usually fall under either of two main types: observational and theoretical . Observational astronomers make direct observations of celestial objects and analyze the data. In contrast, theoretical astronomers create and investigate models of things that cannot be observed. Because it takes millions to billions of years for

738-575: The 15th century, the Timurid astronomer Ulugh Beg compiled the Zij-i-Sultani , in which he catalogued 1,019 stars. Like the earlier catalogs of Hipparchus and Ptolemy, Ulugh Beg's catalogue is estimated to have been precise to within approximately 20 minutes of arc . In the 16th century, Danish astronomer Tycho Brahe used improved instruments, including large mural instruments , to measure star positions more accurately than previously, with

779-588: The 23,882 double and multiple stars and 11,597 variable stars also analyzed during the Hipparcos mission. In 2013, the Gaia satellite was launched and improved the accuracy of Hipparcos . The precision was improved by a factor of 100 and enabled the mapping of a billion stars. Today, the catalogue most often used is USNO-B1.0 , an all-sky catalogue that tracks proper motions, positions, magnitudes and other characteristics for over one billion stellar objects. During

820-500: The 26-inch (660 mm) refractor, a horizontal meridian device, a photographic polar telescope, a big zenith telescope, stellar interferometer , two solar telescopes, coronagraph , a big radio telescope and a variety of labware. The 65 cm Zeiss refractor was originally intended as a gift from then Chancellor of Germany Adolf Hitler to the Italian Benito Mussolini , but it was not delivered and instead

861-496: 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. During its 4-year run, the positions, parallaxes, and proper motions of 118,218 stars were determined with an unprecedented degree of accuracy. A new " Tycho catalog " drew together a database of 1,058,332 stars to within 20-30 mas (milliarcseconds). Additional catalogues were compiled for

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902-488: The Observatory received a zone astrograph and with its help the Russian astronomers catalogued the stars of the near- polar areas of the sky. Regular observation of movements of celestial poles began with the construction of the zenith telescope in 1904. In 1920, the Observatory started transmitting the exact time by radio signals. The observatory participated in the basic geodesic work, namely in measuring degrees of

943-526: The Observatory sent an expedition to Chile to observe stars in the southern skies. Astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth . Astronomers observe astronomical objects , such as stars , planets , moons , comets and galaxies – in either observational (by analyzing the data) or theoretical astronomy . Examples of topics or fields astronomers study include planetary science , solar astronomy ,

984-545: The PhD level and beyond (as of 2024). Contrary to the classical image of an old astronomer peering through a telescope through the dark hours of the night, it is far more common to use a charge-coupled device (CCD) camera to record a long, deep exposure, allowing a more sensitive image to be created because the light is added over time. Before CCDs, photographic plates were a common method of observation. Modern astronomers spend relatively little time at telescopes, usually just

1025-656: The Sun's position for many years using a large astrolabe with a diameter of nearly 1.4 metres. His observations on eclipses were still used centuries later in Canadian–American astronomer Simon Newcomb 's investigations on the motion of the Moon, while his other observations of the motions of the planets Jupiter and Saturn inspired French scholar Laplace 's Obliquity of the Ecliptic and Inequalities of Jupiter and Saturn . In

1066-524: The appointment of Feodor Bredikhin as a director of the Observatory in 1890 and transfer of Aristarkh Belopolsky from the Moscow Observatory, an expert in stellar spectroscopy and solar research. In 1923, they installed a big Littrow spectrograph , and in 1940 – a horizontal solar telescope , manufactured at a Leningrad factory. After having received an astrograph in 1894, the observatory began its work on astrophotography . In 1927,

1107-543: The background stars, which remain fixed. Once a movement per unit time is observed, astronomers compensate for the parallax caused by Earth's motion during this time and the heliocentric distance to this object is calculated. Using this distance and other photographs, more information about the object, including its orbital elements , can be obtained. Asteroid impact avoidance is among the purposes. Quaoar and Sedna are two trans-Neptunian dwarf planets discovered in this way by Michael E. Brown and others at Caltech using

1148-510: The construction after having cleared the territory. In May 1954, the Observatory was re-opened, not only having been restored but considerably expanded in terms of instruments, employees and research subjects. New departments had been created, such as the Department of Radio Astronomy and Department of Instrument Making (with its own optical and mechanical workshop). The surviving old instruments were repaired, modernized and put into service once again. Also installed were new instruments, such as

1189-421: The core sciences, a competency examination, experience with teaching undergraduates and participating in outreach programs, work on research projects under the student's supervising professor, completion of a PhD thesis , and passing a final oral exam . Throughout the PhD training, a successful student is financially supported with a stipend . While there is a relatively low number of professional astronomers,

1230-483: The destroyed 30-inch refractor , and a significant part of the unique library with manuscripts and important works from the 15th to 19th century. On February 5, 1997, nearly 1,500 of the 3,852 books were destroyed by malicious arson and the rest of the library items were damaged by flames, smoke or water. Even before the end of the war, the Soviet government made a decision to restore the Observatory. In 1946, it began

1271-459: 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. NASA's planned Space Interferometry Mission ( SIM PlanetQuest ) (now cancelled) was to utilize astrometric techniques to detect terrestrial planets orbiting 200 or so of

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1312-447: 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 machines and more sophisticated computer technology of the 1960s allowed more efficient compilation of star catalogues . Started in the late 19th century, the project Carte du Ciel to improve star mapping could not be finished but made photography

1353-474: The field is popular among amateurs . Most cities have amateur astronomy clubs that meet on a regular basis and often host star parties . The Astronomical Society of the Pacific is the largest general astronomical society in the world, comprising both professional and amateur astronomers as well as educators from 70 different nations. As with any hobby , most people who practice amateur astronomy may devote

1394-489: The field. Those who become astronomers usually have a broad background in physics, mathematics , sciences, and computing in high school. Taking courses that teach how to research, write, and present papers are part of the higher education of an astronomer, while most astronomers attain both a Master's degree and eventually a PhD degree in astronomy, physics or astrophysics . PhD training typically involves 5-6 years of study, including completion of upper-level courses in

1435-857: The largest refractors in the world at that time (see Great Refractor ). In 1885, the observatory was equipped with 30-inch (760 mm) refractor, which was the biggest usable refractor in the world, until the 36-inch (910 mm) telescope at the Lick Observatory in California a few years later. Both were built by Alvan Clark & Sons in Massachusetts. The principal line of work of the observatory consisted of determination of coordinates of stars and astronomical constants , such as precession , nutation , aberration and refraction , and also discovering and measuring double stars . The observatory's activities have also been connected to

1476-694: The majority of their time working on research, although they quite often have other duties such as teaching, building instruments, or aiding in the operation of an observatory. The American Astronomical Society , which is the major organization of professional astronomers in North America , has approximately 8,200 members (as of 2024). This number includes scientists from other fields such as physics, geology , and engineering , whose research interests are closely related to astronomy. The International Astronomical Union comprises about 12,700 members from 92 countries who are involved in astronomical research at

1517-413: The nearest solar-type stars . The European Space Agency's Gaia Mission , launched in 2013, applies astrometric techniques in its stellar census. In addition to the detection of exoplanets, it can also be used to determine their mass. Astrometric measurements are used by astrophysicists to constrain certain models in celestial mechanics . By measuring the velocities of pulsars , it is possible to put

1558-558: The past 50 years, 7,435 Schmidt camera plates were used to complete several sky surveys that make the data in USNO-B1.0 accurate to within 0.2 arcsec. 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. It

1599-618: The southern stars that could not be seen on the observatory's latitude , the scientists organized two affiliated observing locations. One of them was an astrophysical station in the Crimean town of Simeiz ( Simeiz Observatory ), which had been organized on the basis of a private observatory presented to the Pulkovo Observatory by an astronomy lover N. S. Maltsov in 1908. The other was an astrometric station in Mykolaiv –

1640-498: Was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using physical laws . Today, that distinction has mostly disappeared and the terms "astronomer" and "astrophysicist" are interchangeable. Professional astronomers are highly educated individuals who typically have a PhD in physics or astronomy and are employed by research institutions or universities. They spend

1681-725: Was recovered by the Soviet Union. The Simeiz station became a part of the new Crimean Astrophysical Observatory of the Soviet Academy of Sciences in 1945. They also built the Kislovodsk Mountain Astronomical Station and a laboratory in Blagoveshchensk . The observatory organized many expeditions for determining differences of longitudes , observing passages of Venus and solar eclipses , and studying astroclimate. In 1962,

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