Английская Википедия:Fine Guidance Sensor (HST)

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Шаблон:Short description

Файл:Hubble OTA FOVfgsyellow.png
From the center to outer edge of the FGS field of view is 14.1 arcminutes[1] This is a diagram of the field of view of each Hubble Space Telescope instrument, including the three FGS instruments (FGS field of view(s) highlighted in yellow)
Файл:238888main FGS.JPG
A Fine Guidance Sensor being refurbished between servicing missions SM3A and SM4
Файл:Fgs sm.jpg
A fine guidance sensors in space on STS Servicing Mission 2 in 1997

Fine Guidance Sensor (FGS) for the Hubble Space Telescope is a system of three instruments used for pointing the telescope in space, and also for astrometry and its related sciences.[2] To enable aiming the telescope at a specific spot in the sky, each FGS combines optics and electronics.[2] There are three Hubble FGS, and they have been upgraded over the lifetime of the telescope by crewed Space Shuttle missions.[3] The instruments can support pointing of 2 milli-arc seconds (units of degree).[4] The three FGS are part of the Hubble Space Telescope's Pointing Control System, aka PCS.[5] The FGS function in combination with the Hubble main computer and gyroscopes, with the FGS providing data to the computer as sensors which enables the HST to track astronomical targets.[6]

The FGS can be used to locate something in space, and then lock-on to it.[7] It can provide the movements the telescope must make to keep the object in view, for the main instruments to record data on.[8]

The FGS were originally made by the optics company Perkin-Elmer, and as removable and repairable instruments it has been possible to refurbish them over the lifetime of the telescope.[8] The first replacement FGS was installed in 1997, swapping out FGS1.[5]

In May 2009, on STS-125 a FGS was replaced during the mission to the Hubble telescope by the Space Shuttle.[9] The astronaut crew performed an EVA (spacewalk) to service the FGS and other components on the telescope in Earth orbit.[9] This was the SM4 mission.[6]

An example of astrometry science with the Hubble FGS system is observations of the Low-Mass Binary star system L722-22.[10] Observations were taken of the system in 1990s, and the data helped determine the mass of each of the components of L722-22, which is also known as LHS 1047 and GJ 1005.[10]

The FGS are white-light shearing interferometers.[5] The FGS weigh 220 kg (485 lb) and have dimensions of roughly 0.5 m × 1.0 m × 1.6 meters.[11]

Observations

The smallest Kuiper Belt Object (KBO) yet detected at that time was discovered in 2009 by poring over data from the Hubble Space Telescope's fine guidance sensors.[12] They detected a transit of an object against a distant star, which, based on the duration and amount of dimming, was calculated to be a KBO about Шаблон:Convert in diameter.[12] It has been suggested that the Kepler observatory may be able to detect objects in the Oort cloud by their occultation of background stars,[13] and the Whipple proposal would also try to use this concept.

A Hubble FGS has also been used for astrometry, tracking the movement of different stars.[14] This ability was used for exoplanet research, where the motion of the star caused by the movement of planets around it was detected.[14] Hubble was used via the FGS sensors to detect the motion of star caused by an exoplanet orbiting it.[15] The effect on the red dwarf Gliese 876's by companion Gliese 876b was measured.[15]

FGS was used to study Double-star systems (aka Binary star systems) and to measure distances to astronomical bodies.[15]

FGS has also been used to observe asteroids and calculate their size.[16] Asteroids studied include (63) Ausonia, (15) Eunomia, (43) Ariadne, (44) Nysa, and (624) Hektor.[16]

See also

References

Шаблон:Reflist

External links

Шаблон:Hubble Space Telescope