Astronomical seeing refers to the amount of apparent blurring and twinkling of astronomical objects like stars due to turbulent mixing in the atmosphere of Earth, causing variations of the optical refractive index. The seeing conditions on a given night at a given location describe how much Earth's atmosphere perturbs the images of stars as seen through a telescope; the most common seeing measurement is the full width at half maximum of the optical intensity across the seeing disc. The FWHM of the point spread function is the best possible angular resolution that can be achieved by an optical telescope in a long-exposure image, corresponds to the FWHM of the fuzzy blob seen when observing a point-like source through the atmosphere; the size of the seeing disc is determined by the seeing conditions at the time of the observation. The best conditions give a seeing disk diameter of ~0.4 arcseconds and are found at high-altitude observatories on small islands such as Mauna Kea or La Palma. Seeing is one of the biggest problems for Earth-based astronomy.
While large telescopes have theoretically milli-arcsecond resolution, the real image is limited to the average seeing disc during the observation. This can mean a factor of 100 between the potential and practical resolution. Starting in the 1990s, new adaptive optics have been introduced that can help correct for these effects improving the resolution of ground-based telescopes. Astronomical seeing has several effects: It causes the images of point sources, which in the absence of atmospheric turbulence would be steady Airy patterns produced by diffraction, to break up into speckle patterns, which change rapidly with time Long exposure images of these changing speckle patterns result in a blurred image of the point source, called a seeing disc The brightness of stars appears to fluctuate in a process known as scintillation or twinkling Atmospheric seeing causes the fringes in an astronomical interferometer to move The distribution of atmospheric seeing through the atmosphere causes the image quality in adaptive optics systems to degrade the further you look from the location of reference starThe effects of atmospheric seeing were indirectly responsible for the belief that there were canals on Mars.
In viewing a bright object such as Mars a still patch of air will come in front of the planet, resulting in a brief moment of clarity. Before the use of charge-coupled devices, there was no way of recording the image of the planet in the brief moment other than having the observer remember the image and draw it later; this had the effect of having the image of the planet be dependent on the observer's memory and preconceptions which led the belief that Mars had linear features. The effects of atmospheric seeing are qualitatively similar throughout the visible and near infra-red wavebands. At large telescopes the long exposure image resolution is slightly higher at longer wavelengths, the timescale for the changes in the dancing speckle patterns is lower. There are three common descriptions of the astronomical seeing conditions at an observatory: The full width at half maximum of the seeing disc r0 and t0 The CN2 profileThese are described in the sub-sections below: Without an atmosphere, a small star would have an apparent size, an "Airy disk", in a telescope image determined by diffraction and would be inversely proportional to the diameter of the telescope.
However, when light enters the Earth's atmosphere, the different temperature layers and different wind speeds distort the light waves, leading to distortions in the image of a star. The effects of the atmosphere can be modeled as rotating cells of air moving turbulently. At most observatories, the turbulence is only significant on scales larger than r0 and this limits the resolution of telescopes to be about the same as given by a space-based 10–20 cm telescope; the distortion changes at a high rate more than 100 times a second. In a typical astronomical image of a star with an exposure time of seconds or minutes, the different distortions average out as a filled disc called the point spread function or "seeing disc"; the diameter of the seeing disk, most defined as the full width at half maximum, is a measure of the astronomical seeing conditions. It follows from this definition that seeing is always a variable quantity, different from place to place, from night to night, variable on a scale of minutes.
Astronomers talk about "good" nights with a low average seeing disc diameter, "bad" nights where the seeing diameter was so high that all observations were worthless. The FWHM of the seeing disc is measured in arcseconds, abbreviated with the symbol. A 1.0″ seeing is a good one for average astronomical sites. The seeing of an urban environment is much worse. Good seeing nights tend to be clear, cold nights without wind gusts. Warm air rises, degrading the seeing, clouds. At the best high-altitude mountaintop observatories, the wind brings in stable air which has not been in contact with the ground, sometimes providing seeing as good as 0.4". The astronomical seeing conditions at an observatory can be conveniently described by the parameters r0 and t0. F
Italy the Italian Republic, is a country in Southern Europe. Located in the middle of the Mediterranean Sea, Italy shares open land borders with France, Austria and the enclaved microstates San Marino and Vatican City. Italy covers an area of 301,340 km2 and has a temperate seasonal and Mediterranean climate. With around 61 million inhabitants, it is the fourth-most populous EU member state and the most populous country in Southern Europe. Due to its central geographic location in Southern Europe and the Mediterranean, Italy has been home to a myriad of peoples and cultures. In addition to the various ancient peoples dispersed throughout modern-day Italy, the most famous of which being the Indo-European Italics who gave the peninsula its name, beginning from the classical era and Carthaginians founded colonies in insular Italy and Genoa, Greeks established settlements in the so-called Magna Graecia, while Etruscans and Celts inhabited central and northern Italy respectively; the Italic tribe known as the Latins formed the Roman Kingdom in the 8th century BC, which became a republic with a government of the Senate and the People.
The Roman Republic conquered and assimilated its neighbours on the peninsula, in some cases through the establishment of federations, the Republic expanded and conquered parts of Europe, North Africa and the Middle East. By the first century BC, the Roman Empire emerged as the dominant power in the Mediterranean Basin and became the leading cultural and religious centre of Western civilisation, inaugurating the Pax Romana, a period of more than 200 years during which Italy's technology, economy and literature flourished. Italy remained the metropole of the Roman Empire; the legacy of the Roman Empire endured its fall and can be observed in the global distribution of culture, governments and the Latin script. During the Early Middle Ages, Italy endured sociopolitical collapse and barbarian invasions, but by the 11th century, numerous rival city-states and maritime republics in the northern and central regions of Italy, rose to great prosperity through shipping and banking, laying the groundwork for modern capitalism.
These independent statelets served as Europe's main trading hubs with Asia and the Near East enjoying a greater degree of democracy than the larger feudal monarchies that were consolidating throughout Europe. The Renaissance began in Italy and spread to the rest of Europe, bringing a renewed interest in humanism, science and art. Italian culture flourished, producing famous scholars and polymaths such as Michelangelo, Leonardo da Vinci, Raphael and Machiavelli. During the Middle Ages, Italian explorers such as Marco Polo, Christopher Columbus, Amerigo Vespucci, John Cabot and Giovanni da Verrazzano discovered new routes to the Far East and the New World, helping to usher in the European Age of Discovery. Italy's commercial and political power waned with the opening of trade routes that bypassed the Mediterranean. Centuries of infighting between the Italian city-states, such as the Italian Wars of the 15th and 16th centuries, left the region fragmented, it was subsequently conquered and further divided by European powers such as France and Austria.
By the mid-19th century, rising Italian nationalism and calls for independence from foreign control led to a period of revolutionary political upheaval. After centuries of foreign domination and political division, Italy was entirely unified in 1871, establishing the Kingdom of Italy as a great power. From the late 19th century to the early 20th century, Italy industrialised, namely in the north, acquired a colonial empire, while the south remained impoverished and excluded from industrialisation, fuelling a large and influential diaspora. Despite being one of the main victors in World War I, Italy entered a period of economic crisis and social turmoil, leading to the rise of a fascist dictatorship in 1922. Participation in World War II on the Axis side ended in military defeat, economic destruction and the Italian Civil War. Following the liberation of Italy and the rise of the resistance, the country abolished the monarchy, reinstated democracy, enjoyed a prolonged economic boom and, despite periods of sociopolitical turmoil became a developed country.
Today, Italy is considered to be one of the world's most culturally and economically advanced countries, with the sixth-largest worldwide national wealth. Its advanced economy ranks eighth-largest in the world and third in the Eurozone by nominal GDP. Italy owns the third-largest central bank gold reserve, it has a high level of human development, it stands among the top countries for life expectancy. The country plays a prominent role in regional and global economic, military and diplomatic affairs. Italy is a founding and leading member of the European Union and a member of numerous international institutions, including the UN, NATO, the OECD, the OSCE, the WTO, the G7, the G20, the Union for the Mediterranean, the Council of Europe, Uniting for Consensus, the Schengen Area and many more; as a reflection
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geophysical and volcanology are examples of disciplines for which observatories have been constructed. Observatories were as simple as containing an astronomical sextant or Stonehenge. Astronomical observatories are divided into four categories: space-based, ground-based, underground-based. Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome 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, 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 do not have domes.
For optical telescopes, most ground-based observatories are located far from major centers of population, to avoid the effects of light pollution. The ideal locations for modern observatories are sites that have dark skies, a large percentage of clear nights per year, dry air, are at high elevations. At high elevations, the Earth's atmosphere is thinner, thereby minimizing the effects of atmospheric turbulence and resulting in better astronomical "seeing". Sites that meet the above criteria for modern observatories include the southwestern United States, Canary Islands, the Andes, high mountains in Mexico such as Sierra Negra. A newly emerging site which should be added to this list is Mount Gargash. With an elevation of 3600 m above sea level, it is the home to the Iranian National Observatory and its 3.4m INO340 telescope. Major optical observatories include Mauna Kea Observatory and Kitt Peak National Observatory in the US, Roque de los Muchachos Observatory and Calar Alto Observatory in Spain, Paranal Observatory in Chile.
Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth is Ridge A — a place in the central part of Eastern Antarctica. This location provides the least atmospheric disturbances and best visibility. Beginning in 1930s, radio telescopes have been built for use in the field of radio 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 called radio observatories. Radio observatories are located far from major population centers to avoid electromagnetic interference from radio, TV, other EMI emitting devices, but unlike optical observatories, radio observatories can be placed in valleys for further EMI shielding; some of the world's major radio observatories include the Socorro, in New Mexico, United States, Jodrell Bank in the UK, Arecibo in Puerto Rico, Parkes in New South Wales and Chajnantor in Chile.
Since the mid-20th century, a number of astronomical observatories have been constructed at high altitudes, above 4,000–5,000 m. The largest and most notable of these is the Mauna Kea Observatory, located near the summit of a 4,205 m volcano in Hawaiʻi; the Chacaltaya Astrophysical Observatory in Bolivia, at 5,230 m, was the world's highest permanent astronomical observatory from the time of its construction during the 1940s until 2009. It has now been surpassed by the new University of Tokyo Atacama Observatory, an optical-infrared telescope on a remote 5,640 m mountaintop in the Atacama Desert of Chile; the oldest proto-observatories, in the sense of a private observation post, Wurdi Youang, Australia Zorats Karer, Armenia Loughcrew, Ireland Newgrange, Ireland Stonehenge, Great Britain Quito Astronomical Observatory, located 12 minutes south of the Equator in Quito, Ecuador. Chankillo, Peru El Caracol, Mexico Abu Simbel, Egypt Kokino, Republic of Macedonia Observatory at Rhodes, Greece Goseck circle, Germany Ujjain, India Arkaim, Russia Cheomseongdae, South Korea Angkor Wat, CambodiaThe oldest true observatories, in the sense of a specialized research institute, include: 825 AD: Al-Shammisiyyah observatory, Iraq 869: Mahodayapuram Observatory, India 1259: Maragheh observatory, Iran 1276: Gaocheng Astronomical Observatory, China 1420: Ulugh Beg Observatory, Uzbekistan 1442: Beijing Ancient Observatory, China 1577: Constantinople Observatory of Taqi ad-Din, Turkey 1580: Uraniborg, Denmark 1581: Stjerneborg, Denmark 1642: Panzano Observatory, Italy 1642: Round Tower, Denmark 1633: Leiden Observatory, Netherlands 1667: Paris Observatory, France 1675: Royal Greenwich Observatory, England 1695: Sukharev Tower, Russia 1711: Berlin Observatory, Germany 1724: Jantar Mantar, India 1753: Stockholm Observatory, Sweden 1753: Vilnius University Observatory, Lithuania 1753: Navy Royal Institute and Observatory, Spain 1759: Trieste Observatory, Italy 1757: Macfarlane Observatory, Scotland 1759: Turin Observatory, Italy 1764: Brera Astronomical Observatory, Italy 1765: Mohr Observatory, Indonesia 1774: Vatican Observatory, Vatican 1785: Dunsink Observatory, Ireland 1786: Madras Observatory, India 1789: Armagh Observatory, Northern Ireland 1790: Real Observatorio de Madrid, Spain, 1803: National Astronomical Observatory, Bogotá, Colombia.
1811: Tartu Old Observatory, Estonia 1812: Astronomical Observatory of Capodimonte, Italy 1830/1842: Depot of Charts & Instruments
Birmingham Solar Oscillations Network
The Birmingham Solar Oscillations Network consists of a network of six remote solar observatories monitoring low-degree solar oscillation modes. It is operated by the High Resolution Optical Spectroscopy group of the School of Physics and Astronomy at the University of Birmingham, UK, in collaboration with Sheffield Hallam University, UK, they are funded by Technology Facilities Council. The BiSON has been collecting data continuously on solar oscillations since 1976, making it the longest running helioseismology network with data covering three solar cycles. Professor Yvonne Elsworth Professor Bill Chaplin Anne-Marie Broomhall — Helioseismology Andrea Miglio Steven Hale Mr Ian Barnes — Electronics Mr Barry Jackson — Mechanics BiSON operates automated resonant scattering spectrometers in astronomical domes or mirror fed systems; the network was established in 1976 with two permanent stations. The current sites are: Mount Wilson Observatory, California, USA Las Campanas Observatory, Region IV, Chile Observatorio del Teide, Canary Islands, Spain South African Astronomical Observatory, South Africa OTC Earth Station Carnarvon, Carnarvon, WA, Australia Paul Wild Observatory, Narrabri, NSW, Australia BiSON homepage BiSON Data Realtime BiSON Telemetry and Cameras
Belgium the Kingdom of Belgium, is a country in Western Europe. It is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to the southwest, the North Sea to the northwest, it has a population of more than 11.4 million. The capital and largest city is Brussels; the sovereign state is a federal constitutional monarchy with a parliamentary system. Its institutional organisation is structured on both regional and linguistic grounds, it is divided into three autonomous regions: Flanders in the north, Wallonia in the south, the Brussels-Capital Region. Brussels is the smallest and most densely populated region, as well as the richest region in terms of GDP per capita. Belgium is home to two main linguistic groups or Communities: the Dutch-speaking Flemish Community, which constitutes about 59 percent of the population, the French-speaking Community, which comprises about 40 percent of all Belgians. A small German-speaking Community, numbering around one percent, exists in the East Cantons.
The Brussels-Capital Region is bilingual, although French is the dominant language. Belgium's linguistic diversity and related political conflicts are reflected in its political history and complex system of governance, made up of six different governments. Belgium was part of an area known as the Low Countries, a somewhat larger region than the current Benelux group of states that included parts of northern France and western Germany, its name is derived after the Roman province of Gallia Belgica. From the end of the Middle Ages until the 17th century, the area of Belgium was a prosperous and cosmopolitan centre of commerce and culture. Between the 16th and early 19th centuries, Belgium served as the battleground between many European powers, earning the moniker the "Battlefield of Europe", a reputation strengthened by both world wars; the country emerged in 1830 following the Belgian Revolution. Belgium participated in the Industrial Revolution and, during the course of the 20th century, possessed a number of colonies in Africa.
The second half of the 20th century was marked by rising tensions between the Dutch-speaking and the French-speaking citizens fueled by differences in language and culture and the unequal economic development of Flanders and Wallonia. This continuing antagonism has led to several far-reaching reforms, resulting in a transition from a unitary to a federal arrangement during the period from 1970 to 1993. Despite the reforms, tensions between the groups have remained, if not increased. Unemployment in Wallonia is more than double that of Flanders. Belgium is one of the six founding countries of the European Union and hosts the official seats of the European Commission, the Council of the European Union, the European Council, as well as a seat of the European Parliament in the country's capital, Brussels. Belgium is a founding member of the Eurozone, NATO, OECD, WTO, a part of the trilateral Benelux Union and the Schengen Area. Brussels hosts several of the EU's official seats as well as the headquarters of many major international organizations such as NATO.
Belgium is a developed country, with an advanced high-income economy. It has high standards of living, quality of life, education, is categorized as "very high" in the Human Development Index, it ranks as one of the safest or most peaceful countries in the world. The name "Belgium" is derived from Gallia Belgica, a Roman province in the northernmost part of Gaul that before Roman invasion in 100 BC, was inhabited by the Belgae, a mix of Celtic and Germanic peoples. A gradual immigration by Germanic Frankish tribes during the 5th century brought the area under the rule of the Merovingian kings. A gradual shift of power during the 8th century led the kingdom of the Franks to evolve into the Carolingian Empire; the Treaty of Verdun in 843 divided the region into Middle and West Francia and therefore into a set of more or less independent fiefdoms which, during the Middle Ages, were vassals either of the King of France or of the Holy Roman Emperor. Many of these fiefdoms were united in the Burgundian Netherlands of the 15th centuries.
Emperor Charles V extended the personal union of the Seventeen Provinces in the 1540s, making it far more than a personal union by the Pragmatic Sanction of 1549 and increased his influence over the Prince-Bishopric of Liège. The Eighty Years' War divided the Low Countries into the northern United Provinces and the Southern Netherlands; the latter were ruled successively by the Spanish and the Austrian Habsburgs and comprised most of modern Belgium. This was the theatre of most Franco-Spanish and Franco-Austrian wars during the 17th and 18th centuries. Following the campaigns of 1794 in the French Revolutionary Wars, the Low Countries—including territories that were never nominally under Habsburg rule, such as the Prince-Bishopric of Liège—were annexed by the French First Republic, ending Austrian rule in the region; the reunification of the Low Countries as the United Kingdom of the Netherlands occurred at the dissolution of the First French Empire in 1815, after the defeat of Napo
La Palma San Miguel de La Palma, is the most north-westerly island of the Canary Islands, Spain. La Palma has an area of 706 km2 making it the fifth largest of the seven main Canary Islands; the total population is about 81,863, of which 18,000 live in the capital, Santa Cruz de la Palma and about 20,000 in Los Llanos de Aridane. La Palma has "sister city" status with California, its highest mountain is the Roque de los Muchachos, at 2,426 metres, being second among the peaks of the Canaries only to the peaks of the Teide massif on Tenerife. In 1815, the German geologist Leopold von Buch visited the Canary Islands, it was as a result of his visit to Tenerife, where he visited the Las Cañadas caldera, later to La Palma, where he visited the Taburiente caldera, that the Spanish word for cauldron or large cooking pot – "caldera" – was introduced into the geological vocabulary. In the center of the island is the Caldera de Taburiente National Park. La Palma, like the other islands of the Canary Island archipelago, is a volcanic ocean island.
The volcano rises 7 km above the floor of the Atlantic Ocean. There is road access from sea level to the summit at 2,426 m, marked by an outcrop of rocks called Los Muchachos; this is the site of the Roque de los Muchachos Observatory, one of the world's premier astronomical observatories. La Palma's geography is a result of the volcanic formation of the island; the highest peaks reach over 2,400 m above sea level, the base of the island is located 4,000 m below sea level. The northern part of La Palma is dominated by the Caldera de Taburiente, with a width of 9 km and a depth of 1,500 m, it is surrounded by a ring of mountains ranging from 1,600 m to 2,400 m in height. On its northern side is the exposed remains of the original seamount. Only the deep Barranco de las Angustias ravine leads into the inner area of the caldera, a national park, it can be reached only by hiking. The outer slopes are cut by numerous gorges. Today, only a few of these carry water due to the many water tunnels that have been cut into the island's structure.
From the Caldera de Taburiente to the south runs the ridge Cumbre Nueva – the New Ridge, which despite its name is older than the Cumbre Vieja – Old Ridge. The southern part of La Palma consists of the Cumbre Vieja, a volcanic ridge formed by numerous volcanic cones built of lava and scoria; the Cumbre Vieja is active – but dormant, with the last eruption occurring in 1971 at the Teneguía vent, located at the southern end of the Cumbre Vieja – Punta de Fuencaliente. Beyond Punta de Fuencaliente, the Cumbre Vieja continues in a southerly direction as a submarine volcano. Like all of the Canary Islands, La Palma formed as a seamount through submarine volcanic activity. La Palma is along with Tenerife, the most volcanically active of the Canary Islands and was formed three to four million years ago, its base lies 4,000 m below sea level and reaches a height of 2,426 m above sea level. About a half a million years ago, the Taburiente volcano collapsed with a giant landslide, forming the Caldera de Taburiente.
Erosion has since exposed part of the seamount in the northern sector of the Caldera. Since the Spanish occupation, there have been seven eruptions – all of which have occurred on the Cumbre Vieja: 1470–1492 Montaña Quemada 1585 Tajuya near El Paso 1646 Volcán San Martin 1677 Volcán San Antonio 1712 El Charco 1949 Volcán Nambroque at the Duraznero, Hoyo Negro and Llano del Banco vents 1971 Volcán TeneguíaDuring the 1949 eruption – which commenced on the fiesta of San Juan 24 June 1949 at the Duraznero, 8 July 1949 Llano del Banco vents on the Cumbre Vieja – an earthquake, with an epicentre near Jedy, occurred; this is considered to have caused a 2.5-kilometre-long crack which Bonelli Rubio named "La Grieta" –, to form, with a width of about 1 m and a depth of about 2 m. It attains a maximum displacement of ~4 m in the vicinity of the Hoyo Negro to Duraznero vents, it is not traceable southward from the Duraznero vent. North of the Hoyo Negro it is traceable for ~ 1500 m; the total distance from the southern rim of the Duraznero vent to the Llano del Banco is ~4 km.
In 1951 Ortiz and Bonelli-Rubio published further information in respect of the eruption and associated phenomena that occurred before and during the eruption. There is no indication that the crack has penetrated the edifice of the volcano, due to the absence of Minas Galerias within the Cumbre Vieja, there is no possibility of examining the internal structure of the flank. Carracedo et al.. This means; however the lack of supporting evidence has not stopped claims that the flank is in danger of failing. In a programme transmitted by the British Broadcasting Corporation BBC Horizon broadcast on 12 October 2000, two geologists cited this crack as proof that half of the Cumbre Vieja had moved towards the Atlantic Ocean, they postulate that this process was driven by the pressure caused by the rising magma heating water trapped within the structure of the island. They hypothesised that during a future eruption, the western flank of the Cumbre Vieja, with a mass of 1.5 x1015 kg, could slide into the ocean.
This could potentially generate a giant wave which they termed a "megat
Kiepenheuer Institute for Solar Physics
The Kiepenheuer Institute for Solar Physics is a research institute located in Freiburg, Germany. Its research focuses on the exploration of the heliosphere; the institute has one solar telescope on the Schauinsland Mountain near Freiburg and, in collaboration with other institutions, uses solar telescopes of the Teide Observatory in Tenerife, Spain. The Institute was founded in 1943 as the'Fraunhofer Institute' by Karl-Otto Kiepenheuer. Kiepenheuer was director of the Institute from 1943 until his death in 1975; the Institute was renamed as the'Kiepenheuer Institute for Solar Physics' to honour the founder of the Institute and to enable the Fraunhofer Society to call their own institutes,'Fraunhofer Institutes'. Both Institutions had been named independently after the physicist Joseph von Fraunhofer, they had no other connection besides the name; the solar observatory at the island of Capri, Italy was founded in 1954. The Coudé refractor became operational in 1966, from that time the solar telescope on the Schauinsland continued to be used only for testing equipment.
For several years, the Capri observatory with its domeless telescope provided observation time to the institute. In the early 1970s, the Institute searched for a suitable place to establish a European solar observatory, Karl-Otto Kiepenheuer took an active part in this search; the Spanish island of Tenerife was chosen, due its dry weather and stable atmosphere. In 1989, the Vacuum Tower Telescope became operational, with adaptive optics; the outpost in Capri was closed after the solar observatory at the Teide Observatory became operational. Kiepenheuer Institute for Solar Physics