3 ms·

Bit of an amateur question, but why a bunch of triangles instead of just a perfectly smooth curve?

• dalke 10y ago
  The triangles are curved. https://arxiv.org/ftp/arxiv/papers/1105/1105.3794.pdf https://arxiv.org/ftp/arxiv/papers/1105/1105.3794.pdf says: > The surface of each panel unit has been adjusted to the spherical surface of radius 318.5m other than the overall 300m radius of the main reflector, which will make it better fit to a paraboloid. They are also under dynamic control, through cables connected to the triangles (see figure 6 from that paper). Quoting http://earthsky.org/todays-image/china-five-hundred-meter-aperture-spherical-telescope http://earthsky.org/todays-image/china-five-hundred-meter-ap... : > Unlike Arecibo, which has a fixed spherical curvature, FAST will use active optics. Its surface will adjust in different directions with more flexibility than the surface of Arecibo. That means it’ll cover the sky within 40° from the zenith, or overhead point, in contrast to Arecibo’s 20° range. Quoting http://www.caltechmicrowave.org/fast-telescope http://www.caltechmicrowave.org/fast-telescope > It will use an active surface that adjusts to create parabolas in different directions, with an effective dish size of 300 m. This means that it will not be confined to pointing directly upwards, but capable of covering the sky within 40 degrees from the zenith. Its working frequency will be 0.3 to 3.0 GHz, with a pointing precision of 4 arcseconds.