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Hipparcos
Hipparcos satellite (artist's conception)
Artist's conception of Hipparcos in space
General information
Organization European Space Agency
Launch date 8 August 1989
Launch vehicle Ariane 4
Mission length 3. The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member Events 1220 - Sweden is defeated by Estonian tribes in the Battle of Lihula. Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) Ariane 4 was an Expendable launch system, designed by the Centre National d'Etudes Spatiales and manufactured and marketed by its subsidiary Arianespace 5 years
Type of orbit Elliptical
Orbit height 507 to 35,888 km

Hipparcos (an acronym for High Precision Parallax Collecting Satellite) was an astrometry mission of the European Space Agency (ESA) dedicated to the measurement of stellar parallax and the proper motions of stars. In Astrodynamics or Celestial mechanics an elliptic orbit is a Kepler orbit with the eccentricity greater than 0 and less than 1 Acronyms, initialisms, and alphabetisms are Abbreviations that are formed using the initial components in a phrase or name Astrometry is the branch of Astronomy that relates to precise measurements and explanations of the positions and movements of Stars and other celestial bodies The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member Parallax is an apparent displacement or difference of orientation of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between The proper motion of a Star is the measurement of its change in position in the sky over time after Improper motions are accounted for A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth The project was named in honor of Hipparchus. Hipparchus ( Greek; ca 190 BC &ndash ca 120 BC was a Greek Astronomer, Geographer, and Mathematician of the Hellenistic Ideas for such a mission dated from 1967, with the mission accepted by ESA in 1980.

Contents

Mission

The Hipparcos satellite was a product of Matra Marconi Space, Alenia Spazio and their industrial partners. Matra Marconi Space ( MMS) was a Franco - British aerospace company. Thales Alenia Space is the company born after Thales had bought the participation of Alcatel in the two Joint-ventures between Alcatel and Finmeccanica The optical system had a 290 mm aperture, 1400 mm focal length folded Schmidt telescope. The focal length of an optical system is a measure of how strongly it converges (focuses or diverges (diffuses Light. A Schmidt camera, also referred to as the Schmidt telescope, is an astronomical Camera designed to provide wide fields of view with limited The expected precision of the instrument was in the range of 0. 001–0. 002 arcsecond. A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60 of one degree. The satellite also included solar panels for power and an s-band antenna for communication. The S band ranges from 2 to 4  GHz, crossing the (artificial boundary between UHF and SHF at 3 [1]

The satellite was launched by an Ariane 4 on 8 August 1989. Ariane 4 was an Expendable launch system, designed by the Centre National d'Etudes Spatiales and manufactured and marketed by its subsidiary Arianespace Events 1220 - Sweden is defeated by Estonian tribes in the Battle of Lihula. Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) The launch mass of Hipparcos was 500 kg. [2] The original goal was to place the satellite in a geostationary orbit above the earth, but failure of the apogee boost motor resulted in a highly elliptical orbit from 507 to 35,888 km altitude. A geostationary orbit (GEO is a Geosynchronous orbit directly above the Earth 's Equator (0° Latitude) with a period equal to the Earth's In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from In Mathematics, an ellipse (from the Greek ἔλλειψις literally absence) is a Conic section, the locus of points in a In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star Altitude is the Elevation of a point or object from a known level or datum (plural data Despite this difficulty, all of the scientific goals were accomplished. Communications were terminated on 15 August 1993. Events 778 - The Battle of Roncevaux Pass, at which Roland is killed Year 1993 ( MCMXCIII) was a Common year starting on Friday (link will display full 1993 Gregorian calendar)

The program was divided in two parts: the Hipparcos experiment whose goal was to measure the five astrometric parameters of some 120,000 stars to a precision of some 2 to 4 milliarcseconds and the Tycho experiment, whose goal was the measurement of the astrometric and two-colour photometric properties of some 400,000 additional stars to a somewhat lower precision. Astrometry is the branch of Astronomy that relates to precise measurements and explanations of the positions and movements of Stars and other celestial bodies "Milli" redirects here for the village in Azerbaijan see Birinci Milli; for similar-sounding words see Millie. A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60 of one degree. Photometry is a technique of Astronomy concerned with measuring the Flux, or intensity of an Astronomical object 's Electromagnetic

Due to the built-in beam-splitter, Hipparcos continuously scanned the sky in two directions, separated by 58°. The image was split into a grid by 3,000 parallel slits, allowing the separation of the stars in the field of view to be measured to a high degree of accuracy. [3]

Results

The final Hipparcos Catalogue (120,000 stars with 1 milliarcsec level astrometry) and the final Tycho Catalogue (more than one million stars with 20-30 milliarcsec astrometry and two-colour photometry) were completed in August 1996. The Hipparcos and Tycho Catalogues (Tycho-1 are the primary products of the European Space Agency 's astrometric mission Hipparcos. The catalogues were published by ESA in June 1997.

The Hipparcos and Tycho data have been used to create the Millennium Star Atlas: an all-sky atlas of one million stars to visual magnitude 11, from the Hipparcos and Tycho Catalogues and 10,000 nonstellar objects included to complement the catalogue data. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value

There were questions over whether Hipparcos has a systematic error of about 1 milliarcsec in at least some parts of the sky. The value determined by Hipparcos for the distance to the Pleiades is about 10% less than the value obtained by some other methods. The Pleiades (ˈpliːədiːz or /ˈplaɪədiːz/ also known as M 45, the '''Seven Sisters''', Seven Stars, SED, Matariki As of 2007, the controversy remained unresolved. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. [4][5]

In order to resolve these issues, Floor van Leeuwen published reevaluated results. [6][7]

See also

References

  1. ^ Peraldi, A. Full-sky Astrometric Mapping Explorer (or FAME) is an astrometric Satellite designed to determine with unprecedented accuracy the positions distances Gaia is a European Space Agency (ESA Astrometry space mission and a successor to the ESA Hipparcos mission (October 4-6, 1982). "The Hipparcos payload optics". Technology for Space Astrophysics Conference: The Next 30 Years: 88-95, Danbury, CT: American Institute of Aeronautics and Astronautics. Retrieved on 2007-06-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1381 - Peasants' Revolt: in England, rebels arrive at Blackheath.  
  2. ^ Staff (June 12, 2007). Hipparcos. ESA. Retrieved on 2007-06-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1381 - Peasants' Revolt: in England, rebels arrive at Blackheath.
  3. ^ Turon, Catherine (1997). From Hipparchus to Hipparcos: Measuring the Universe, One Star at a Time. Sky Publishing Corporation. Retrieved on 2007-06-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1381 - Peasants' Revolt: in England, rebels arrive at Blackheath.
  4. ^ den Hond, Bas (September 30, 2004). Did the Pleiades "blind" Hipparcos?. Astronomy Magazine. Retrieved on 2007-06-12. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1381 - Peasants' Revolt: in England, rebels arrive at Blackheath.
  5. ^ Soderblom, D. R. ; Nelan, E. ; Benedict, G. F. ; McArthur, B. ; Ramirez, I. ; Spiesman, W. ; Jones, B. F (2005). "Confirmation of Errors in Hipparcos Parallaxes from Hubble Space Telescope Fine Guidance Sensor Astrometry of the Pleiades". The Astronomical Journal 129: 1616–1624. doi:10.1086/427860. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  
  6. ^ "Scientist reworks star distances", BBC, September 28, 2007. Events 48 BC - Pompey the Great is assassinated on orders of King Ptolemy of Egypt after landing in Egypt. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.  
  7. ^ "Hipparcos, the New Reduction of the Raw Data" . Astrophysics and Space Science Library 350.  

External links

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