Arecibo Observatory 305-m fixed spherical reflecting antenna
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Telescope Name: William E. Gordon Telescope

Description: 305-m fixed spherical reflecting antenna with movable secondary for pointing.

Observatory Name: Arecibo Observatory

Aperture (m): 305

Coordinate system: International Terrestrial Reference Frame 2000 (ITRF2000)

Ellipsoid:         Geodetic Reference System 1980 (GRS80)

Geodetic Longitude:     -66 45 09.70

Geodetic Latitude:      +18 20 39.19

Geocentric Longitude:   -66 45 09.70

Geocentric Latitude:    +18 13 46.45

Astronomical Longitude: -66 45 08.00

Astronomical Latitude:  +18 21 13.07

Elevation (above geoid):    496.84 m

Elevation (above GRS80):    453.34 m

Geocentric X:           2390487.55 m

Geocentric Y:          -5564731.65 m

Geocentric Z:           1994725.93 m

Telescope Logical Id: urn:nasa:pds:context:telescope:arecibo.305m

Notes: Operational 1963-2020. Accuracy of position is approximately 1 m.

Description:
            Arecibo's 305-m fixed spherical reflecting radio antenna was the primary telescope
            at Arecibo Observatory between 1963 and 2020, when it was irreparably damaged by a
            series of failures in its supporting cables.  Because the surface was spherical,
            the antenna used 'line' feeds, each connected to receivers in 'carriage houses'
            supported above the reflector by towers and cables. In the late 1990s one of the
            carriage houses was replaced with reflecting optics that corrected the spherical
            aberration over a wide bandwidth, reduced receiver noise by a factor of several,
            and made gain less dependent on pointing.  The antenna was 'pointed' over angles of
            approximately 0-20 degrees from zenith by by moving the carriage houses. Initially
            the antenna was used for radio astronomy above 50 MHz and solar system radar
            astronomy (including active probing of Earth's upper atmosphere) at 430 MHz. In the
            mid-1970s, the reflecting surface was improved and new receivers and transmitters
            were added, allowing radio observations to 11 GHz and radar operation at 2380 MHz.

            The position of the telescope was detemined through surveying and comparison to
            stations determined using the Global Positioning System.