Atacama Pathfinder Experiment
Encyclopedia
The Atacama Pathfinder Experiment (APEX) is a radio telescope
located at 5,100 meters above sea level, at the Llano de Chajnantor Observatory
in the Atacama desert
, in northern Chile
, 50 kilometers to the east of San Pedro de Atacama
. The main dish has a diameter of 12 meters and consists of 264 aluminium panels with an average surface accuracy of 17 micrometres (r.m.s.). The telescope was officially inaugurated on September 25, 2005.
The APEX telescope is a modified ALMA
(Atacama Large Millimeter Array) prototype antenna and is located at the future site of the ALMA observatory. It will find many targets that ALMA will be able to study in great detail. APEX is designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range — between infrared light and radio waves. Submillimetre astronomy opens a window into the cold, dusty and distant Universe, but the faint signals from space are heavily absorbed by water vapour in the Earth's atmosphere. Chajnantor is an ideal location for such a telescope, as the region is one of the driest on the planet and is more than 750 m higher than the observatories on Mauna Kea, and 2400 m higher than the Very Large Telescope (VLT) on Cerro Paranal.
APEX is a collaboration between the Max Planck Institute for Radio Astronomy
(MPIfR) at 50%, Onsala Space Observatory
(OSO) at 23%, and the European Organisation for Astronomical Research in the Southern Hemisphere
(ESO) at 27%. The telescope was designed and constructed by VERTEX Antennentechnik GmbH (Germany
), under contract by MPIfR. The operation of APEX in Chajnantor is entrusted to ESO.
APEX science goals include studying the formation of stars, planets, and galaxies, including very distant galaxies in the early Universe, and the physical conditions of molecular clouds. Its first results proved the telescope lives up to the ambitions of the scientists by providing access to the "Cold Universe" with unprecedented sensitivity and image quality. As a demonstration, no less than 26 articles based on early science with APEX were published in July 2006 in a special issue of the research journal Astronomy & Astrophysics. Among the many new findings published then, most in the field of star formation and astrochemistry, are the discovery of a new interstellar molecule, and the detection of light emitted at 0.2 mm from CO molecules, as well as light coming from a charged molecule composed of two forms of Hydrogen.
Recent APEX observations lead to the first ever discovery of hydrogen peroxide in space, the first image of a dusty disc closely encircling a massive baby star, providing direct evidence that massive stars form in the same way as their smaller brethren, and the first direct measurements of the size and brightness of regions of star-birth in a very distant galaxy.
All ESO and Swedish APEX data are stored in the ESO archive. These data follow the standard ESO archive rules, i.e. they become publicly available 1 year after they have been delivered to the principal investigator of the project.
For its first observations, APEX was equipped with state-of-the-art sub-millimetre spectrometers developed by MPIfR's Division for Sub-Millimetre Technology and, more recently, with the first facility receiver built at Chalmers University (OSO).
For more information about APEX instruments, consult the instrumentation page.
The Apex telescope is made up of three "receiver" cabins : Cassegrain, Nasmyth A and Nasmyth B.
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...
located at 5,100 meters above sea level, at the Llano de Chajnantor Observatory
Llano de Chajnantor Observatory
Llano de Chajnantor Observatory is an astronomical observatory located at an altitude of 5,104 m in the Chilean Atacama desert, 50 kilometers to the east of San Pedro de Atacama. It is a very dry site - inhospitable to humans - but an excellent site for submillimetre astronomy...
in the Atacama desert
Atacama Desert
The Atacama Desert is a plateau in South America, covering a strip of land on the Pacific coast, west of the Andes mountains. It is, according to NASA, National Geographic and many other publications, the driest desert in the world...
, in northern Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, 50 kilometers to the east of San Pedro de Atacama
San Pedro de Atacama
San Pedro de Atacama is a Chilean town and commune in El Loa Province, Antofagasta Region. It is located east of Antofagasta, some 106 km southeast of Calama and the Chuquicamata copper mine, overlooking the Licancabur volcano. It features a significant archeological museum, the R. P...
. The main dish has a diameter of 12 meters and consists of 264 aluminium panels with an average surface accuracy of 17 micrometres (r.m.s.). The telescope was officially inaugurated on September 25, 2005.
The APEX telescope is a modified ALMA
Atacama Large Millimeter Array
The Atacama Large Millimeter/sub-millimeter Array is an array of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array is being constructed on the Chajnantor plateau at 5000 metres altitude...
(Atacama Large Millimeter Array) prototype antenna and is located at the future site of the ALMA observatory. It will find many targets that ALMA will be able to study in great detail. APEX is designed to work at sub-millimetre wavelengths, in the 0.2 to 1.5 mm range — between infrared light and radio waves. Submillimetre astronomy opens a window into the cold, dusty and distant Universe, but the faint signals from space are heavily absorbed by water vapour in the Earth's atmosphere. Chajnantor is an ideal location for such a telescope, as the region is one of the driest on the planet and is more than 750 m higher than the observatories on Mauna Kea, and 2400 m higher than the Very Large Telescope (VLT) on Cerro Paranal.
APEX is a collaboration between the Max Planck Institute for Radio Astronomy
Max Planck Institute for Radio Astronomy
The Max Planck Institute for Radio Astronomy is located in Bonn, Germany. It is one of 80 institutes in the Max Planck Society .-History:...
(MPIfR) at 50%, Onsala Space Observatory
Onsala Space Observatory
Onsala Space Observatory , the Swedish National Facility for Radio Astronomy, provides scientists with equipment to study the Earth and the rest of the Universe. The observatory operates two radio telescopes in Onsala, 45 km south of Göteborg, and takes part in several international projects...
(OSO) at 23%, and the European Organisation for Astronomical Research in the Southern Hemisphere
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
(ESO) at 27%. The telescope was designed and constructed by VERTEX Antennentechnik GmbH (Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
), under contract by MPIfR. The operation of APEX in Chajnantor is entrusted to ESO.
Science
Submillimetre astronomy is a relatively unexplored frontier in astronomy and reveals a Universe that cannot be seen in the more familiar visible or infrared light. It is ideal for studying the "cold Universe": light at these wavelengths shines from vast cold clouds in interstellar space, at temperatures only a few tens of degrees above absolute zero. Astronomers use this light to study the chemical and physical conditions in these molecular clouds — the dense regions of gas and cosmic dust where new stars are being born. Seen in visible light, these regions of the Universe are often dark and obscured due to the dust, but they shine brightly in the millimetre and submillimetre part of the spectrum. This wavelength range is also ideal for studying some of the earliest and most distant galaxies in the Universe, whose light has been redshifted into these longer wavelengths.APEX science goals include studying the formation of stars, planets, and galaxies, including very distant galaxies in the early Universe, and the physical conditions of molecular clouds. Its first results proved the telescope lives up to the ambitions of the scientists by providing access to the "Cold Universe" with unprecedented sensitivity and image quality. As a demonstration, no less than 26 articles based on early science with APEX were published in July 2006 in a special issue of the research journal Astronomy & Astrophysics. Among the many new findings published then, most in the field of star formation and astrochemistry, are the discovery of a new interstellar molecule, and the detection of light emitted at 0.2 mm from CO molecules, as well as light coming from a charged molecule composed of two forms of Hydrogen.
Recent APEX observations lead to the first ever discovery of hydrogen peroxide in space, the first image of a dusty disc closely encircling a massive baby star, providing direct evidence that massive stars form in the same way as their smaller brethren, and the first direct measurements of the size and brightness of regions of star-birth in a very distant galaxy.
All ESO and Swedish APEX data are stored in the ESO archive. These data follow the standard ESO archive rules, i.e. they become publicly available 1 year after they have been delivered to the principal investigator of the project.
Instruments
APEX, the largest submillimetre-wavelength telescope operating in the southern hemisphere, has a suite of different instruments for astronomers to use in their observations, a major one being LABOCA, the Large APEX Bolometer Camera. LABOCA uses an array of extremely sensitive thermometers — known as bolometers — to detect submillimetre light. With almost 300 pixels, it is the largest such camera in the world. In order to be able to detect the tiny temperature changes caused by the faint submillimetre radiation, each of these thermometers is cooled to less than 0.3 degrees above absolute zero — a frigid minus 272.85 degrees Celsius. LABOCA's high sensitivity, together with its wide field of view (one third of the diameter of the full Moon), make it an invaluable tool for imaging the submillimetre Universe.For its first observations, APEX was equipped with state-of-the-art sub-millimetre spectrometers developed by MPIfR's Division for Sub-Millimetre Technology and, more recently, with the first facility receiver built at Chalmers University (OSO).
For more information about APEX instruments, consult the instrumentation page.
Technology
In order to operate at the shorter sub-millimetre wavelengths, APEX presents a surface of exceedingly high quality: after a series of high precision adjustments, the APEX project team was able to adjust the surface of the mirror with remarkable precision: over the 12m diameter of the antenna, the deviation from the perfect parabola is now less than 17 thousandths of a millimetre. This is smaller than one fifth of the average thickness of a human hair.The Apex telescope is made up of three "receiver" cabins : Cassegrain, Nasmyth A and Nasmyth B.
External links
- ESO APEX website
- Sub-millimetre Astronomy in Full Swing on Southern Skies — ESOESOESO, as a three-letter abbreviation, may stand for:* European Southern Observatory* Ensemble Studios Online* English Symphony Orchestra* Edmonton Symphony Orchestra* Executive Stock Options...
Organisational Release