The termobservatoire has been used in French since at least 1976 to denote any institution that compiles and presents data on a particular subject (such aspublic health observatory) or for a particular geographic area (European Audiovisual Observatory).
Astronomical observatories are mainly divided into four categories according to location:space-based,airborne, ground-based, and underground-based. Historically, ground-based observatories were as simple as containing amural instrument (for measuring the angle betweenstars) orStonehenge (which has some alignments on astronomical phenomena). Astronomical observatories may be private or they may bepublic.
Haleakala Observatory at 3,036 metres (9,961 feet), Maui, Hawaii
Ground-based observatories, located on the surface of Earth, are used to make observations in theradio andvisible light portions of theelectromagnetic spectrum. Mostoptical telescopes are housed within adome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened during observing, and closed when the telescope is not in use. In most cases, the entire upper portion of the telescope dome can be rotated to allow the instrument to observe different sections of the night sky. Radio telescopes usually do not have domes.[citation needed]
Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth isRidge A—a place in the central part of Eastern Antarctica.[7] This location provides the least atmospheric disturbances and best visibility.[citation needed]
Beginning in 1933,radio telescopes have been built for use in the field ofradio astronomy to observe the Universe in the radio portion of the electromagnetic spectrum. Such an instrument, or collection of instruments, with supporting facilities such as control centres, visitor housing, data reduction centers, and/or maintenance facilities are calledradio observatories. Radio observatories are similarly located far from major population centers to avoidelectromagnetic interference (EMI) fromradio,TV,radar, and other EMI emitting devices, but unlike optical observatories, radio observatories can be placed invalleys for further EMI shielding. Some of the world's major radio observatories include theVery Large Array inNew Mexico, United States,Jodrell Bank in theUK,Arecibo inPuerto Rico,Parkes inNew South Wales, Australia, andChajnantor inChile. A related discipline isVery-long-baseline interferometry (VLBI).[citation needed]
Since the mid-20th century, a number of astronomical observatories have been constructed at veryhigh altitudes, above 4,000–5,000 m (13,000–16,000 ft). The largest and most notable of these is theMauna Kea Observatory, located near the summit of a 4,205 m (13,796 ft) volcano in Hawaiʻi. TheChacaltaya Astrophysical Observatory in Bolivia, at 5,230 m (17,160 ft), was the world's highest permanent astronomical observatory[8] from the time of its construction during the 1940s until 2009. It has now been surpassed by the newUniversity of Tokyo Atacama Observatory,[9] an optical-infrared telescope on a remote 5,640 m (18,500 ft) mountaintop in theAtacama Desert of Chile.
Ancient Indian observatory at Delhi
"El Caracol" observatory temple atChichen Itza, Mexico
Space-based observatories are telescopes or other instruments that are located inouter space, many inorbit around the Earth. Space telescopes can be used to observe astronomical objects at wavelengths of the electromagnetic spectrum that cannot penetrate theEarth's atmosphere and are thus impossible to observe using ground-based telescopes. The Earth's atmosphere isopaque toultraviolet radiation,X-rays, andgamma rays and is partially opaque toinfrared radiation so observations in these portions of the electromagnetic spectrum are best carried out from a location above the atmosphere of our planet.[29] Another advantage of space-based telescopes is that, because of their location above the Earth's atmosphere, their images are free from the effects of atmospheric turbulence that plague ground-based observations.[30] As a result, theangular resolution of space telescopes such as theHubble Space Telescope is often much smaller than a ground-based telescope with a similaraperture. However, all these advantages do come with a price. Space telescopes are much more expensive to build than ground-based telescopes. Due to their location, space telescopes are also extremely difficult to maintain. The Hubble Space Telescope was able to be serviced by theSpace Shuttles while many other space telescopes cannot be serviced.
Airborne observatories have the advantage of height over ground installations, putting them above most of the Earth's atmosphere. They also have an advantage over space telescopes: The instruments can be deployed, repaired and updated much more quickly and inexpensively. TheKuiper Airborne Observatory and theStratospheric Observatory for Infrared Astronomy use airplanes to observe in theinfrared, which is absorbed bywater vapor in the atmosphere.High-altitude balloons for X-ray astronomy have been used in a variety of countries.[citation needed]
A marine observatory is a scientific institution whose main task is to make observations in the fields of meteorology, geomagnetism and tides that are important for the navy and civil shipping. An astronomical observatory is usually also attached. Some of these observatories also deal with nautical weather forecasts and storm warnings, astronomical time services, nautical calendars and seismology.
A magnetic observatory is a facility which precisely measures the total intensity of Earth'smagnetic field for field strength and direction at standard intervals. Geomagnetic observatories are most useful when located away from human activities to avoid disturbances of anthropogenic origin, and the observation data is collected at a fixed location continuously for decades. Magnetic observations are aggregated, processed, quality checked and made public through data centers such asINTERMAGNET.[31][32]
The types of measuring equipment at an observatory may includemagnetometers (torsion, declination-inclination fluxgate, proton precession, Overhauser-effect), variometer (3-component vector, total-field scalar),dip circle,inclinometer, earth inductor,theodolite, self-recording magnetograph, magnetic declinometer, azimuth compass. Once a week at the absolute reference point calibration measurements are performed.[33]
Avolcano observatory is an institution that conducts the monitoring of avolcano as well as research in order to understand the potential impacts of active volcanism. Among the best known are theHawaiian Volcano Observatory and theVesuvius Observatory. Mobile volcano observatories exist with theUSGS VDAP (Volcano Disaster Assistance Program), to be deployed on demand. Each volcano observatory has a geographicarea of responsibility it is assigned to whereby the observatory is tasked with spreading activity forecasts, analyzing potential volcanic activity threats and cooperating with communities in preparation forvolcanic eruption.[34]
^Saunders, Will; Lawrence, Jon S.; Storey, John W. V.; Ashley, Michael C. B.; Kato, Seiji; Minnis, Patrick; Winker, David M.; Liu, Guiping & Kulesa, Craig (2009). "Where Is the Best Site on Earth? Domes A, B, C, and F, and Ridges A and B".Publications of the Astronomical Society of the Pacific.121 (883):976–992.arXiv:0905.4156.Bibcode:2009PASP..121..976S.doi:10.1086/605780.S2CID11166739.
^Kennedy, Edward S. (1962). "Review:The Observatory in Islam and Its Place in the General History of the Observatory by Aydin Sayili".Isis.53 (2):237–239.doi:10.1086/349558.
Aubin, David; Charlotte Bigg, andH. Otto Sibum, eds.The Heavens on Earth: Observatories and Astronomy in Nineteenth-Century Science and Culture (Duke University Press; 2010) 384 pages; Topics include astronomy as military science in Sweden, thePulkovo Observatory in the Russia ofCzar Nicholas I, and physics and the astronomical community in late 19th-century America.
Brunier, Serge, et al.Great Observatories of the World (2005).
Gressot Julien and Jeanneret Romain, « Determining the right time, or the establishment of a culture of astronomical precision at Neuchâtel Observatory in the mid-19th century »,Journal for the History of Astronomy,53(1), 2022, 27–48,https://doi.org/10.1177/00218286211068572
Leverington, David.Observatories and Telescopes of Modern Times – Ground-Based Optical and Radio Astronomy Facilities since 1945. Cambridge University Press, Cambridge 2017,ISBN9780521899932.