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Hipparcos and satellite
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.
According to the Hipparcos satellite, Arcturus is 36. 7 light years ( 11. 3 parsecs ) from Earth, relatively close in astronomical terms.
Clusters such as the Pleiades, Hyades and a few others within about 500 light years are close enough for this method to be viable, and results from the Hipparcos position-measuring satellite yielded accurate distances for several clusters.
For example, the Hipparcos satellite took measurements for over 100, 000 nearby stars.
The Hipparcos catalogue was compiled from the data gathered by the European Space Agency's astrometric satellite Hipparcos, which was operational from 1989 to 1993.
However, greatly improved distance measurements to globular clusters using the Hipparcos satellite and increasingly accurate measurements of the Hubble constant resolved the paradox, giving an age for the universe of about 13 billion years and an age for the oldest stars of a few hundred million years less.
However, Struve's initial result was actually surprisingly close to the currently accepted value of 0. 129 ″, as determined by the Hipparcos astrometry satellite.
Results prior to the launch of the Hipparcos satellite generally found that the Pleiades were about 135 parsecs away from Earth.
* 1989-- Earth-Success-Launch of the Hipparcos satellite
The Hipparcos satellite, the Hubble Space Telescope, and infrared color-magnitude diagram fitting have been used to establish a distance of ~ 153 ly ( 47 pc ) to the cluster center.
Based upon parallax measurements made with Hipparcos astrometry satellite, α Arietis is about from Earth.
This is a class A star on the main sequence approximately from Earth as measured by the Hipparcos astrometry satellite.
In 1989, the satellite Hipparcos was launched primarily for obtaining parallaxes and proper motions of nearby stars, increasing the reach of the method tenfold.
Based upon parallax measurements with the Hipparcos astrometry satellite, Kapteyn's Star is at a distance of from the Earth.
As determined by the Hipparcos astrometry satellite, it is approximately away.
Based upon parallax measurements from the astrometric Hipparcos satellite, the distance to this system is about.
Hipparcos ( an acronym for " High precision parallax collecting satellite ") was a scientific mission of the European Space Agency ( ESA ), launched in 1989 and operated between 1989 and 1993.
The Hipparcos satellite was financed and managed under the overall authority of the European Space Agency.
The Hipparcos satellite was launched ( with the direct broadcast satellite TV-SAT2 as co-passenger ) on an Ariane 4 launch vehicle, flight V33, from Kourou, French Guiana, on 8 August 1989.
Including an estimate for the scientific activities related to the satellite observations and data processing, Hipparcos mission cost some 600 MEuro ( 2000 economic conditions ), and its
Although fully superseded by the satellite results, it nevertheless includes supplemental information on multiple system components as well as compilations of radial velocities and spectral types which, not observed by the satellite, were not included in the published Hipparcos Catalogue.
Upsilon Andromedae is located fairly close to the Solar System: the parallax of Upsilon Andromedae A was measured by the Hipparcos astrometry satellite as 74. 12 milliarcseconds, corresponding to a distance of 13. 49 parsecs ( 44 light years ).

Hipparcos and also
Additional catalogues were compiled for the 23, 882 double / multiple stars and 11, 597 variable stars also analyzed during the Hipparcos mission.
Hipparcos 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 our current ability to make it out.
Delta Cephei is also of particular importance as a calibrator of the Cepheid period-luminosity relation since its distance is among the most precisely established for a Cepheid, thanks in part to its membership in a star cluster and the availability of precise Hubble Space Telescope / Hipparcos parallaxes.
The name of the space telescope Hipparcos was an acronym for High Precision Parallax Collecting Satellite, and also reflected the name of the Greek astronomer Hipparchus.

Hipparcos and study
The Hipparcos satellite has recently greatly improved both the proper motion and parallax estimates of nearby bright stars, refining the study of this and other moving groups.
The most recent determination of the system orbital elements comes from a study by George Gatewood using older sources along with data from the Hipparcos satellite.

Hipparcos and so
Even so, Hipparcos is only able to measure parallax angles for stars up to about 1, 600 light-years away, a little more than one percent of the diameter of the Milky Way Galaxy.

Hipparcos and its
Spectroscopic estimates of Rigel's distance place its distance between, while Hipparcos < nowiki >'</ nowiki > s measurement of its parallax gives a distance of, with a margin of error of about 9 %.
Similarly to its predecessor Hipparcos, Gaia consists of two telescopes providing two observing directions with a fixed, wide angle between them.
It is from the Sun as measured by the Hipparcos astrometry satellite, which, as the distance is nearly 10 parsecs, means its absolute magnitude is almost equal to its apparent magnitude.
Initially thought to be around 1500 light years distant, the Alnitak system's distance was determined to be roughly half that via measurement of its stellar parallax by the Hipparcos satellite.
In 2000, preliminary Hipparcos astrometrical satellite data indicated that the orbital inclination of the star's companion was 0. 5 °, implying that its mass was as much as 115 times Jupiter's.
HD 217107 is fairly close to the Sun: the Hipparcos astrometric satellite measured its parallax as 50. 71 Milliarcseconds, which corresponds to a distance of 65 light years.
This star is currently about from Earth, but its proper motion, distance, and radial velocity indicate that it will approach within a very small distance — perhaps under one light year — from the Sun within 1. 4 million years, based on past and current Hipparcos data.

Hipparcos and distance
Its distance is uncertain ; pre-Hipparcos estimates centered around 220 light-years, while Hipparcos data suggest a distance of 418 light-years, albeit with a margin of error of ~ 14 %.
Yet some authors argue that the controversy over the distance to the Pleiades discussed below is a red herring, since the cosmic distance ladder can ( presently ) rely on a suite of other nearby clusters where consensus exists regarding the distances as established by Hipparcos and independent means ( e. g., the Hyades, Coma Berenices cluster, etc.
Data from Hipparcos yielded a surprising result, namely a distance of only 118 parsecs by measuring the parallax of stars in the cluster — a technique that should yield the most direct and accurate results.
Later work consistently argued that the Hipparcos distance measurement for the Pleiades was erroneous.
However, the author of the 2007 – 2009 catalog of revised Hipparcos parallaxes reasserted that the distance to the Pleiades is ~ 120 pc, and challenged the dissenting evidence.
Recently, Francis and Anderson proposed that a systematic effect on Hipparcos parallax errors for stars in clusters biases calculation using the weighted mean, and gave a Hipparcos parallax distance of 126 pc, and photometric distance 132 pc based on stars in the AB Doradus, Tucana-Horologium and Beta Pictoris moving groups, which are similar in age and composition to the Pleiades.
At an estimated distance of 110 parsecs from Hipparcos, this corresponds to a radius of about 280 million kilometers ( or 170 million miles ), which is roughly 400R < sub >☉</ sub > or 1. 87 AU .< ref name =" NOTERADIUS " group =" note "> To determine the Rasalgheti's radius in terms of solar units, the calculations begin with the formula for angular diameter as follows:
The distance to this star can be deduced from the parallax measurements made during the Hipparcos, yielding a value of.
Parallax measurements from the Hipparcos satellite yield an estimated distance of from Earth.

0.132 seconds.