Difference between revisions 1813704 and 1813705 on enwikiversity

[[Image:Skylab-73-HC-440HR.jpg|thumb|right|200px|The Saturn V SA-513 lifts off to boost the Skylab Orbital Workshop into Earth orbit on March 14, 1973. Credit: NASA.]]
[[Astronomy]] is performed by location and is subject to local conditions. The shapes and sizes of observatories have changed over time, as have their altitude. The motivations for putting an observatory manned or unmanned at different altitudes has led to a great variety in '''lofting technology'''.
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| title=Arecibo: Celestial Eavesdropper
| author=Frederic Castel
| publisher=Space.com
| date=8 May 2000
| accessdate=2008-09-02 |archiveurl=http://web.archive.org/web/20000619110005/http://www.space.com/scienceastronomy/astronomy/arecibo_profile_000508.html|archivedate=2000-06-19}}</ref> The dish surface is made of 38,778 perforated aluminum panels, each measuring about 3 by 6 feet (1 by 2 m), supported by a mesh of steel cables.


"The telescope has three radar transmitters, with [[w:EIRP|effective isotropic radiated powers]] of 20 TW at 2380&nbsp;MHz, 2.5 TW (pulse peak) at 430&nbsp;MHz, and 300 MW at 47&nbsp;MHz. The telescope is a [[w:spherical reflector|spherical reflector]], not a [[w:parabolic reflector|parabolic reflector]]. To aim the telescope, the receiver is moved to intercept signals reflected from different directions by the spherical dish surface. A parabolic mirror would induce a varying [[w:astigmatism|astigmatism]] when the receiver is in different positions off the focal point, but the [[w:spherical aberration|error of a spherical mirror]] is the same in every direction."<ref name=AreciboObservatory/>

"The receiver is located on a 900-ton platform which is suspended 150&nbsp;m (500&nbsp;ft) in the air above the dish by 18 cables running from three [[w:Reinforced concrete|reinforced concrete]] towers, one of which is 110&nbsp;m (365&nbsp;ft) high and the other two of which are 80&nbsp;m (265&nbsp;ft) high (the tops of the three towers are at the same elevation). The platform has a 93-meter-long rotating bow-shaped track called the azimuth arm on which receiving antennas, secondary and tertiary reflectors are mounted. This allows the telescope to observe any region of the sky within a forty-degree cone of visibility about the local zenith (between −1 and 38 degrees of declination). Puerto Rico's location near the equator allows Arecibo to view all of the planets in the Solar System, though the round trip light time to objects beyond [[Saturn]] is longer than the time the telescope can track it, preventing radar observations of more distant objects."<ref name=AreciboObservatory/>
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==National Observatory of Athens==
[[Image:Obser.jpg|thumb|right|200px|This image shows the setting for the National Observatory of Athens. Credit: [[w:User:Dimboukas|Dimboukas]].]]
The National Observatory of Athens is 107 m asl.

The new 63 cm telescope in Penteli is used extensively by the astronomers of the Institute.
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