Llano de Chajnantor Observatory

Llano de Chajnantor Observatory
Location Antofagasta Region, Chile
Coordinates 23°01′22″S 67°45′18″W / 23.0228°S 67.755°W / -23.0228; -67.755Coordinates: 23°01′22″S 67°45′18″W / 23.0228°S 67.755°W / -23.0228; -67.755
Altitude 4,800 m (15,700 ft)
Telescopes Atacama Large Millimeter Array, Atacama Pathfinder Experiment, Atacama Submillimeter Telescope Experiment, NANTEN2 Observatory, Atacama Cosmology Telescope, QUIET, POLARBEAR, University of Tokyo Atacama Observatory

Llano de Chajnantor Observatory is the name for a group of astronomical observatories located at an altitude of over 4,800 m (15,700 ft) in the Atacama Desert of northern Chile. The site is in the Antofagasta Region approximately 50 kilometres (31 mi) east of the town of San Pedro de Atacama. The exceptionally arid climate of the area is inhospitable to humans, but creates an excellent location for millimeter, submillimeter, and mid-infrared astronomy.[1] This is because water vapour absorbs and attenuates submillimetre radiation. Llano de Chajnantor is home to the largest and most expensive astronomical telescope project in the world, the Atacama Large Millimeter Array (ALMA). Llano de Chajnantor and the surrounding area has been designated as the Chajnantor Science Reserve (Spanish: Reserva Científica de Chajnantor) by the government of Chile.[2]

Site description

The Llano de Chajnantor is located on the western side of the Puna de Atacama, which is another name for the southern part of the Altiplano. The main ridge of the Andes is over 200 kilometres (120 mi) to the east, well into Argentina. The Salar de Atacama basin borders the Puna de Atacama to the west, which in turn is bordered by the Cordillera Domeyko. The western side of the Puna de Atacama is dotted with the volcanoes of the Central Volcanic Zone of the Andean Volcanic Belt. The Llano de Chajnantor site itself is bounded by volcanic peaks of the Purico Complex, which have been active in the Holocene but have not erupted in historic times.[3] Cerro Chajnantor is to the north, Cerro El Chascón to the east, and smaller peaks to the south and west. The Pampa la Bola lies to the northeast, north of Cerro El Chascón and east of Cerro Chajnantor. Llano de Chajnantor has an average elevation of 5,000 m (16,000 ft), while Pampa la Bola averages 4,800 m (15,700 ft). The thin atmosphere makes work difficult for humans, so much of the activity for ALMA will be conducted at a base camp in the Salar de Atacama basin at approximately 2,900 m (9,500 ft) in elevation.

360-degree panorama of the Chajnantor plateau

Rainfall at the ALMA site averages 100 mm (3.9 in) annually.[4] The dry climate of Llano de Chajnantor is due to three factors: the rain shadows created by the Andes and the Chilean Coastal Range, the inversion created by the Humboldt Current off the coast of Chile, and dry air descending between the Hadley cell and the Ferrel cell, which forms the South Pacific High.[5] While the site is generally viewed as being in the Atacama Desert, in terms of ecoregions it is in the Central Andean dry puna. Llano de Chajnantor is at the same latitude as deserts in southern Africa and central Australia.


Telescopes on Llano de Chajnantor

The Atacama Pathfinder Experiment (APEX), a new-technology 12-m telescope in operation since 2005 on Llano de Chajnantor

Telescopes on Pampa la Bola

Telescopes on adjacent peaks

APEX Under the Moon. Starry night on the Chajnantor Plateau in the Chilean Andes[10]

Former telescopes

See also


  1. Bustos, R.; Rubio, M.; Otárola, A.; Nagar, N. (2014). "Parque Astronómico de Atacama: An Ideal Site for Millimeter, Submillimeter, and Mid-Infrared Astronomy". Publications of the Astronomical Society of the Pacific. 126 (946): 1126. arXiv:1410.2451Freely accessible. Bibcode:2014PASP..126.1126B. doi:10.1086/679330.
  2. "Topographical Map of CONICYT Science Preserve" (PDF). National Radio Astronomy Observatory. Retrieved 2012-01-26.
  3. "Purrico Complex". Global Volcanism Program. Smithsonian Institution. Retrieved 2012-01-26.
  4. "The best observing sites on Earth". Atacama Large Millimeter/submillimeter Array. Retrieved 2012-01-26.
  5. Garreaud, René D.; Molina, Alejandra; Farias, Marcelo (2010). "Andean uplift, ocean cooling and Atacama hyperaridity: A climate modeling perspective". Earth and Planetary Science Letters. 292: 39. Bibcode:2010E&PSL.292...39G. doi:10.1016/j.epsl.2010.01.017.
  6. Wootten, A.; Thompson, A.R. (2009). "The Atacama Large Millimeter/Submillimeter Array". Proceedings of the IEEE. 97 (8): 1463. arXiv:0904.3739Freely accessible. Bibcode:2009IEEEP..97.1463W. doi:10.1109/JPROC.2009.2020572.
  7. Güsten, R.; Nyman, L. Å.; Schilke, P.; Menten, K.; Cesarsky, C.; Booth, R. (2006). "The Atacama Pathfinder EXperiment (APEX) – a new submillimeter facility for southern skies –". Astronomy and Astrophysics. 454 (2): L13. Bibcode:2006A&A...454L..13G. doi:10.1051/0004-6361:20065420.
  8. Kohno, K. (2005). "The Atacama Submillimeter Telescope Experiment". The Cool Universe: Observing Cosmic Dawn. 344: 242. Bibcode:2005ASPC..344..242K.
  9. Kawamura, A.; Mizuno, N.; Yonekura, Y.; Onishi, T.; Mizuno, A.; Fukui, Y. (2005). "NANTEN2: A Submillimeter Telescope for Large Scale Surveys at Atacama". Astrochemistry: Recent Successes and Current Challenges. 235: 275P. Bibcode:2005IAUS..235P.275K.
  10. "APEX Under the Moon". ESO Picture of the Week. Retrieved 12 February 2013.
  11. Fowler, J. W.; Niemack, M. D.; Dicker, S. R.; Aboobaker, A. M.; Ade, P. A. R.; Battistelli, E. S.; Devlin, M. J.; Fisher, R. P.; et al. (2007). "Optical design of the Atacama Cosmology Telescope and the Millimeter Bolometric Array Camera". Applied Optics. 46 (17): 3444–54. arXiv:astro-ph/0701020Freely accessible. Bibcode:2007ApOpt..46.3444F. doi:10.1364/AO.46.003444. PMID 17514303.
  12. Minezaki, Takeo; Kato, Daisuke; Sako, Shigeyuki; Konishi, Masahiro; Koshida, Shintaro; Mitani, Natsuko; Aoki, Tsutomu; Doi, Mamoru; Handa, Toshihiro (2010). Stepp, Larry M; Gilmozzi, Roberto; Hall, Helen J, eds. "The University of Tokyo Atacama 1.0-m Telescope". Proceedings of SPIE. 7733: 773356. doi:10.1117/12.856694. |chapter= ignored (help)
  13. Radford, S. J. E.; Giovanelli, R.; Sebring, T. A.; Zmuidzinas, J. (2009). "Ccat". Submillimeter Astrophysics and Technology: a Symposium Honoring Thomas G. Phillips ASP Conference Series. 417: 113. Bibcode:2009ASPC..417..113R.
  14. Keating, B.; Moyerman, S.; Boettger, D.; Edwards, J.; Fuller, G.; Matsuda, F.; Miller, N.; Paar, H.; Rebeiz, G.; et al. (2011). "Ultra High Energy Cosmology with POLARBEAR". 1110: 2101. arXiv:1110.2101Freely accessible. Bibcode:2011arXiv1110.2101K.
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