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Information about Hipparcos

Hipparcos

Hipparcos satellite in space (artist's conception).
General information
Organization:European Space Agency
Launched:8 August 1989
Launch vehicle:Ariane 4
Orbit height:507 to 35,888 km
Type of orbit:Elliptical
 


Hipparcos (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. The project was named in honor of Hipparchus. Ideas for such a mission dated from 1967, with the mission accepted by ESA in 1980.

Mission

The Hipparcos satellite was a product of Matra Marconi Space, Alenia Spazio and their industrial partners. The optical system had a 290 mm aperture, 1400 mm focal length folded Schmidt telescope. The expected precision of the instrument was in the range of 0.001–0.002 arcseconds. The satellite also included solar panels for power and an s-band antenna for communication.[1]

The satellite was launched by an Ariane 4 on 8 August 1989. 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. Despite this difficulty, all of the scientific goals were accomplished. Communications were terminated on 15 August 1993.

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 milli-arcsec 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.

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 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.

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. As of 2007, the controversy remained unresolved.[4][5]

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

See also

References

1. ^ Peraldi, A. (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. 
2. ^ Staff (June 12, 2007). Hipparcos. ESA. Retrieved on 2007-06-12.
3. ^ Turon, Catherine (1997). From Hipparchus to Hipparcos: Measuring the Universe, One Star at a Time. Sky Publishing Corporation. Retrieved on 2007-06-12.
4. ^ den Hond, Bas (September 30, 2004). Did the Pleiades "blind" Hipparcos?. Astronomy Magazine. Retrieved on 2007-06-12.
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. Retrieved on 2007-06-12. 
6. ^ "Scientist reworks star distances", BBC, September 28, 2007.2007"> 
7. ^ "Hipparcos, the New Reduction of the Raw Data". Astrophysics and Space Science Library 350. Retrieved on 2007-10-17. 

External links

European Space Agency (ESA), established in 1974, is an inter-governmental organisation dedicated to the exploration of space, currently with 17 member states. Its headquarters are in Paris.
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August 8 is the 1st day of the year (2nd in leap years) in the Gregorian calendar. There are 0 days remaining.

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Ariane 4 was an expendable launch system, designed by the Centre National d'Etudes Spatiales and manufactured and marketed by its subsidiary Arianespace.

The development program began in 1983 and the first successful launch was on 15 June 1988.
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Astrometry is the branch of astronomy that relates to precise measurements and explanations of the positions and movements of stars and other celestial bodies. Although once thought of as an esoteric field with little useful application for the future, the information obtained by
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European Space Agency (ESA), established in 1974, is an inter-governmental organisation dedicated to the exploration of space, currently with 17 member states. Its headquarters are in Paris.
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Parallax, or more accurately motion parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, caused by the motion of an
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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. This contrasts with radial velocity which is the measurement of the change in distance toward or away from the viewer over time.
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STAR is an acronym for:

Organizations:
  • Society for Telescopy, Astronomy, and Radio, a non-profit astronomy club in New Jersey
  • Special Tasks and Rescue or Special Tactics and Response, synonyms for SWAT

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Hipparchus (Greek Ἵππαρχος; ca. 190 BC – ca. 120 BC) was a Greek astronomer, geographer, and mathematician of the Hellenistic period.
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Matra Marconi Space (MMS) was a Franco-British aerospace company.

Marta Marconi Space was established in 1990 as a joint venture between the space and telecommunication divisions of the Lagardère Group (Matra Espace) and the GEC group (Marconi Space Systems).
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Thales Alenia Space

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Founded April 10, 2007
Headquarters Cannes

Key people Pascale Sourisse, President and CEO
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Operating income 1.8 billions euros (2004)
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In optics, an aperture is a hole or an opening through which light is admitted. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane.
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F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror.]] The focal length of an optical system is a measure of how strongly it converges (focuses) or diverges (diffuses) light.
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A Schmidt camera is an astronomical camera designed to provide wide fields of view with limited aberrations. Other similar designs are the Wright Camera and Lurie-Houghton telescope.
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A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60) of one degree. [1] Since one degree is defined as one three hundred sixtieth (1/360) of a circle, 1 MOA is 1/21600 of the amount of arc in a closed circle, or
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The S band ranges from 2 to 4 GHz., crossing the imaginary boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum.
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Ariane 4 was an expendable launch system, designed by the Centre National d'Etudes Spatiales and manufactured and marketed by its subsidiary Arianespace.

The development program began in 1983 and the first successful launch was on 15 June 1988.
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August 8 is the 1st day of the year (2nd in leap years) in the Gregorian calendar. There are 0 days remaining.

Events

  • 1220 - Sweden was defeated by Estonian tribes in the Battle of Lihula.

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A geostationary orbit (GEO) is a geosynchronous orbit directly above the Earth's equator (0° latitude), with orbital eccentricity of zero. From the ground, a geostationary object appears motionless in the sky and is therefore the orbit of most interest to operators
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ellipse (from the Greek ἔλλειψις, literally absence) is the locus of points on a plane where the sum of the distances from any point on the curve to two fixed points is constant.
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ORBit is a CORBA compliant Object Request Broker (ORB). The current version is called ORBit2 and is compliant with CORBA version 2.4. It is developed under the GPL license and is used as middleware for the GNOME project.
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For other uses see Altitude (disambiguation)


Altitude is the elevation of an object from a known level or datum (plural: data). Common data are mean sea level and the surface of the WGS-84 geoid, used by GPS.
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August 15 is the 1st day of the year (2nd in leap years) in the Gregorian calendar. There are 0 days remaining.

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Astrometry is the branch of astronomy that relates to precise measurements and explanations of the positions and movements of stars and other celestial bodies. Although once thought of as an esoteric field with little useful application for the future, the information obtained by
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An SI prefix (also known as a metric prefix) is a name or associated symbol that precedes a unit of measure (or its symbol) to form a decimal multiple or submultiple.
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A minute of arc, arcminute, or MOA is a unit of angular measurement, equal to one sixtieth (1/60) of one degree. [1] Since one degree is defined as one three hundred sixtieth (1/360) of a circle, 1 MOA is 1/21600 of the amount of arc in a closed circle, or
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