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- Active_surface abstract "An active surface is a surface of a radio telescope that is under active computer control of its shape. Large (more than 10 m in diameter or length) radio telescopes always bend during operation, due to their enormous weight and the fact that even the strongest materials are not perfectly stiff. This bending, typically in the range of a few millimetres, does not affect low frequency operation much, but dramatically reduces the efficiency of the telescope at higher frequencies where the wavelengths are comparable to the distortion. Typically, the efficiency of a telescope drops appreciably when the deviation from the desired shape is more than 1/10 of the considered wavelength. An active surface uses numerous small actuators to move the surface panels with respect to the underlying frame, and thus maintain the correct shape.An active surface can try to compensate for many different types of errors. The first is gravity - this is simplest since previous measurements, or even a mathematical model, can be used to predict (and correct) any bending. More difficult is correction for wind and thermal errors, since these require measuring and correcting in real time.The most notable examples of active surfaces areGreen Bank TelescopeLarge Millimeter TelescopeSardinia Radio TelescopeNoto Radio Observatory".
- Active_surface wikiPageExternalLink abs_all.jsp?arnumber=1373995.
- Active_surface wikiPageExternalLink p0639.pdf.
- Active_surface wikiPageID "19918926".
- Active_surface wikiPageRevisionID "564954809".
- Active_surface hasPhotoCollection Active_surface.
- Active_surface subject Category:Astronomical_imaging.
- Active_surface subject Category:Astronomical_instruments.
- Active_surface subject Category:Radio_telescopes.
- Active_surface type Artifact100021939.
- Active_surface type AstronomicalInstruments.
- Active_surface type AstronomicalTelescope102751295.
- Active_surface type Device103183080.
- Active_surface type Instrument103574816.
- Active_surface type Instrumentality103575240.
- Active_surface type Magnifier103709206.
- Active_surface type Object100002684.
- Active_surface type PhysicalEntity100001930.
- Active_surface type RadioTelescope104044716.
- Active_surface type RadioTelescopes.
- Active_surface type ScientificInstrument104147495.
- Active_surface type Telescope104403638.
- Active_surface type Whole100003553.
- Active_surface comment "An active surface is a surface of a radio telescope that is under active computer control of its shape. Large (more than 10 m in diameter or length) radio telescopes always bend during operation, due to their enormous weight and the fact that even the strongest materials are not perfectly stiff.".
- Active_surface label "Active surface".
- Active_surface sameAs m.04qb2k7.
- Active_surface sameAs Q4677590.
- Active_surface sameAs Q4677590.
- Active_surface sameAs Active_surface.
- Active_surface wasDerivedFrom Active_surface?oldid=564954809.
- Active_surface isPrimaryTopicOf Active_surface.