The Arecibo Observatory in Puerto Rico after the RATAN 600, the second largest radio telescope in the world. The verb contained in the name " recibo " in Spanish means " I receive ".
The spherical reflector of the radio telescope is pivoted and has a diameter of 304.8 m. This is embedded in a natural bowl- shaped valley about 15 km south of Arecibo in the north of Puerto Rico. The three-year construction began in the summer of 1960 and was completed with the inauguration on 1 November 1963.
Arecibo is operated on behalf of the National Science Foundation ( NSF) from Cornell University. As it was originally designed for the Ionospheric, the telescope Arecibo Ionospheric Observatory was first called (AIO ) and was subordinate to the U.S. Department of Defense. In October 1969, the establishment of the NSF was taken over and renamed in September 1971 in the National Astronomy and Ionosphere Center ( NAIC).
The telescope is open to all astronomers - some 200 researchers each year to use the facility. The observation time is awarded by an independent panel of the incoming requests worldwide.
Around the reflector are three large support poles - two are 80.8 m high, the third is 30.4 m higher to compensate for the terrain differences. From each mast go from six long cables, where over the center of the reflector in 137.2 m a triangular platform is attached. Because a bent Azimutarm is rotatably mounted on an annular track. The 100 m long arm serves to align the receiver of the telescope. These are located in the "Gregorian Dome": two sub-reflectors that concentrate the signals.
Although the reflector of the telescope is fixed, can these different adjustment sky objects with a declination between about 1 ° and 38 ° are observed for a period of time by the recipient of the movement of the object to be tracked at the sky.
In the receivers antennas for different frequency ranges of the radio band are available to cover more observation tasks. Conversely, the antenna can also emit a signal into the bowl, which is then reflected into space. Thus, the radio telescope of Arecibo can also be used as a transmitter, for example, radar observations of planets and asteroids. At the observatory, which is available around the clock in operation, about 140 people are employed.
- Effective Diameter: 304.8m
- Surface of the reflector: 73,000 m²
- Surface accuracy: 2.2 mm (RMS)
- Depth of the spherical mirror: 50.9 m
- Weight of the antenna platform: 816 t
- Height above the mirror surface: 137.2 m
- Transmission Power: 500 kW
- Reception range: 300 MHz to 10 GHz
The Arecibo message and SETI
The radio telescope was used to broadcast the Arecibo message. This radio signal has the objective to provide information about the humanity of possibly existing extraterrestrial civilizations. The main initiators of this project were Frank Drake and Carl Sagan.
At times, the Arecibo Observatory to search for extraterrestrial intelligence ( SETI ) is employed.