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PPM Star Catalogue
The PPM Star Catalogue (Positions and Proper Motions Star Catalogue) is the successor of the SAO Catalogue. It contains precise positions and proper motions of 378,910 stars on the whole sky in the J2000/FK5 coordinate system. It is designed to represent as closely as possible the IAU (1976) coordinate system on the sky, as defined by the FK5 star catalogue. Thus, the PPM is an extension of the FK5 system to higher star densities and fainter magnitudes. Description The PPM can be considered a replacement of two preceding astrometric catalogs which served a similar purpose: AGK3 and the SAO Catalog. In contrast to the PPM, these older catalogs are based on (1) the now obsolete FK4 system of positions and proper motions, and (2) only two position measures per star. While the SAO catalog is more or less complete to V=9, with 4,503 stars fainter than V=10, the PPM catalog is fairly complete to V=9.5, with 102,672 stars fainter than V=10 and 22,395 stars fainter than V=11. Release ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smithsonian Astrophysical Observatory Star Catalog
The Smithsonian Astrophysical Observatory Star Catalog is an astrometric star catalogue, created by Smithsonian Institution, a research institute. It was published by the Smithsonian Astrophysical Observatory in 1966 and contains 258,997 stars. The catalogue was compiled from various previous astrometric catalogues, and contains only stars to about ninth magnitude for which accurate proper motions were known. Names in the SAO catalogue start with the letters SAO, followed by a number. The numbers are assigned following 18 ten-degree bands of declination, with stars sorted by right ascension within each band. Online version of the SAO Catalog was created by the HEASARC in March 2001 based on ADC/CDS Catalog I/131A, which itself is originally derived from a character-coded machine-readable version of the Smithsonian Astrophysical Observatory Star Catalog (SAO, SAO Staff 1966) prepared by T.A. Nagy in 1979, and subsequently modified over the next decade or so. Examples of S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night; their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material largely comprising hydrogen, helium, and traces of heavier elements. Its stellar mass, total mass mainly determines it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a celestial body, as they are subject to perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodies) can be used to generate an ephemeris, a table of values giving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star Catalogue
A star catalogue is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some of the more frequently quoted ones. Star catalogues were compiled by many different ancient people, including the Babylonians, Greeks, Chinese, Persians, and Arabs. They were sometimes accompanied by a star chart for illustration. Most modern catalogues are available in electronic format and can be freely downloaded from space agencies' data centres. The largest is being compiled from the spacecraft '' Gaia'' and thus far has over a billion stars. Completeness and accuracy are described by the faintest limiting magnitude V (largest number) and the accuracy of the positions. Historical catalogues Ancient Near East From their existing records, it is known that the ancient Egyptians recorded th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrometric
Astrometry 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. History 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 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 the '' Almagest'', giving their location, coordinates, and brightness. In the 10th century, the Iranian astronomer Abd al-Rahman al-Sufi carried out observation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AGK3
The ''Astronomische Gesellschaft Katalog'' (AGK) is an astrometric star catalogue of the Northern hemisphere. It was published in 3 versions from 1890 until 1975, named AGK1, AGK2 and AGK3. History Compilation for the first version, Astronomische Gesellschaft Katalog 1 AGK1, was started in 1867, directed by Friedrich Argelander and published between 1890 (three sections from the observatories at Oslo, Helsinki, and Neuchâtel Observatory) and 1924 (final section: Algiers Observatory), listing 200 000 stars down to ninth magnitude. The second version, AGK2, was started in the 1920s, and published between 1951 and 1958 using photographic data obtained from the Bonn and Hamburg Observatories. Karl Friedrich Küstner was involved in the planning for star catalog AGK2 with the Bonn part then directed by Ernst Arnold Kohlschütter. The third version, AGK3, was started in 1956 and published in 1975. It contains 183,145 stars north of declination –2° with mean positional error ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Downloadable
In computer networks, download means to ''receive'' data from a remote system, typically a server such as a web server, an FTP server, an email server, or other similar systems. This contrasts with uploading, where data is ''sent to'' a remote server. A ''download'' is a file offered for downloading or that has been downloaded, or the process of receiving such a file. Definition Downloading generally transfers entire files for local storage and later use, as contrasted with streaming, where the data is used nearly immediately while the transmission is still in progress and may not be stored long-term. Websites that offer streaming media or media displayed in-browser, such as YouTube, increasingly place restrictions on the ability of users to save these materials to their computers after they have been received. Downloading on computer networks involves retrieving data from a remote system, like a web server, FTP server, or email server, unlike uploading, where data is sent to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States's civil list of government space agencies, space program, aeronautics research and outer space, space research. National Aeronautics and Space Act, Established in 1958, it succeeded the National Advisory Committee for Aeronautics (NACA) to give the American space development effort a distinct civilian orientation, emphasizing peaceful applications in space science. It has since led most of America's space exploration programs, including Project Mercury, Project Gemini, the 1968–1972 Apollo program missions, the Skylab space station, and the Space Shuttle. Currently, NASA supports the International Space Station (ISS) along with the Commercial Crew Program and oversees the development of the Orion (spacecraft), Orion spacecraft and the Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SAO Catalogue
The Smithsonian Astrophysical Observatory Star Catalog is an astrometric star catalogue, created by Smithsonian Institution, a research institute. It was published by the Smithsonian Astrophysical Observatory in 1966 and contains 258,997 stars. The catalogue was compiled from various previous astrometric catalogues, and contains only stars to about ninth magnitude for which accurate proper motions were known. Names in the SAO catalogue start with the letters SAO, followed by a number. The numbers are assigned following 18 ten-degree bands of declination, with stars sorted by right ascension within each band. Online version of the SAO Catalog was created by the HEASARC in March 2001 based on ADC/CDS Catalog I/131A, which itself is originally derived from a character-coded machine-readable version of the Smithsonian Astrophysical Observatory Star Catalog (SAO, SAO Staff 1966) prepared by T.A. Nagy in 1979, and subsequently modified over the next decade or so. Examples of SAO c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
