Each individual or small group of astronomical knowledge recorders among the hominids after some effort has realized that they are on the surface of a planet, an approximately spheroidal object. Further, when any of them study the sky, they have realized they are only sensing a small portion relative to their location (such as in the enjoyment of backyard astronomy). To combine what they've learned, when they get together to discuss it or record it, they have to locate that knowledge where that knowledge occurred. This locating eventually included the radiation received to form the knowledge and science of astronomical radiation geography.
Geographical radiation astronomy is the study of the effect of geography on radiation astronomy. Both astronomical radiation geography and geographical radiation astronomy are part of astrogeography, or astrography.
Notation: let the symbol Def. indicate that a definition is following.
Notation: let the symbols between [ and ] be replacement for that portion of a quoted text.
To help with definitions, their meanings and intents, there is the learning resource theory of definition.
Def. evidence that demonstrates that a concept is possible is called proof of concept.
The proof-of-concept structure consists of
- findings, and
The findings demonstrate a statistically systematic change from the status quo or the control group.
Seeing an orange Sun due to atmospheric effects and feeling the warmth of its rays is probably a student's first encounter with an apparent astronomical orange radiation source.
Def. "the expanse of space that seems to be over the earth like a dome" is called the sky, or sometimes the heavens.
This definition applies especially well to an individual on top of the Earth's solid crust looking around at what lies above and off to the horizon in all directions. Similarly, it applies to an individual's visual view while floating on a large body of water, where off on the horizon is still water.
The image at upper right shows the horizon marking the lower edge of the sky and the upper edge of the Atlantic Ocean, with a layer of cumulus clouds just above.
A more general definition of 'sky' allows for skies as seen on other worlds. At left is a 360° panarama of the horizon on Mars as perceived in the visual true-color range of the NASA Mars Exploration Rover 'Spirit' on November 23-8, 2005.
Def. an "expanse of space that seems to be [overhead] like a dome" is called a sky.
Even in day light, the sky may seem absent of objects if a nearby source tends to overwhelm other luminous objects.
At lower right is a view of the horizon on the Moon's solid surface taken by an Apollo 16 astronaut. The image shows a black sky without stars because the sunlight coming from the left is overwhelming.
“Mean sea level (MSL) is a measure of the average height of the ocean's surface (such as the halfway point between the mean high tide and the mean low tide); used as a standard in reckoning land elevation. MSL also plays an extremely important role in aviation, where standard sea level pressure is used as the measurement datum of altitude at flight levels.”
The upper figure at right shows "the change in annually averaged sea level at 23 geologically stable tide gauge sites with long-term records as selected by Douglas (1997). The thick dark line is a three-year moving average of the instrumental records. This data indicates a sea level rise of ~27.5 cm from 1800-2000. Because of the limited geographic coverage of these records, it is not obvious whether the apparent decadal fluctuations represent true variations in global sea level or merely variations across regions that are not resolved."
"For comparison, the recent annually averaged satellite altimetry data  from TOPEX/Poseidon are shown in red. These data indicate a somewhat higher rate of increase than tide gauge data, however the source of this discrepancy is not obvious. It may represent systematic error in the satellite record and/or incomplete geographic sampling in the tide gauge record. The month to month scatter on the satellite measurements is roughly the thickness of the plotted red curve."
The second figure at the right "shows changes in sea level during the Holocene, the time following the end of the most recent glacial period, based on data from Fleming et al. 1998, Fleming 2000, & Milne et al. 2005. These papers collected data from various reports and adjusted them for subsequent vertical geologic motions, primarily those associated with post-glacial continental and hydroisostatic rebound. The first refers to deformations caused by the weight of continental ice sheets pressing down on the land, the latter refers to uplift in coastal areas resulting from the increased weight of water associated with rising sea levels. It should be noted that because of the latter effect and associated uplift, many islands, especially in the Pacific, exhibited higher local sea levels in the mid Holocene than they do today. Uncertainty about the magnitude of these corrections is the dominant uncertainty in many measurements of Holocene scale sea level change."
"The black curve is based on minimizing the sum of squares error weighted distance between this curve and the plotted data. It was constructed by adjusting a number of specified tie points, typically placed every 1 kyr and forced to go to 0 at the modern day. A small number of extreme outliers were dropped. It should be noted that some authors propose the existence of significant short-term fluctuations in sea level such that the sea level curve might oscillate up and down about this ~1 kyr mean state. Others dispute this and argue that sea level change has been a smooth and gradual process for essentially the entire length of the Holocene. Regardless of such putative fluctuations, evidence such as presented by Morhange et al. (2001) suggests that in the last 10 kyr sea level has never been higher than it is at present."
The lower "figure shows sea level rise since the end of the last glacial episode based on data from Fleming et al. 1998, Fleming 2000, & Milne et al. 2005."
"[A]t least one episode of rapid deglaciation, known as meltwater pulse 1A, is agreed upon and indicated on the plot. A variety of other accelerated periods of deglaciation have been proposed (i.e. MWP-1B, 2, 3, 4), but it is unclear if these actually occurred or merely reflect misinterpretation of difficult measurements. No other events are evident in the data presented above."
"The lowest point of sea level during the last glaciation is not well constrained by observations (shown here as a dashed curve), but is generally argued to be approximately 130 +/- 10 m below present sea level and to have occurred at approximately 22 +/- 3 thousand years ago. The time of lowest sea level is more or less equivalent to the last glacial maximum. Prior to this time, ice sheets were still increasing in size so that sea level was decreasing almost continuously over a period of approximately 100,000 years."
Horizontal coordinate system
“The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane. This coordinate system divides the sky into the upper hemisphere where objects are visible, and the lower hemisphere where objects cannot be seen since the earth is in the way. The great circle separating hemispheres [is] called [the] celestial horizon or rational horizon. The pole of the upper hemisphere is called the zenith. The pole of the lower hemisphere is called the nadir. ”
“The horizontal coordinates are:
- Altitude (Alt), sometimes referred to as elevation, is the angle between the object and the observer's local horizon. It is expressed as an angle between 0 degrees to 90 degrees.
- Azimuth (Az), that is the angle of the object around the horizon, usually measured from the north increasing towards the east.
- Zenith distance, the distance from directly overhead (i.e. the zenith) is sometimes used instead of altitude in some calculations using these coordinates. The zenith distance is the complement of altitude (i.e. 90°-altitude).”
"The horizontal coordinate system is fixed to the Earth, not the stars. Therefore, the altitude and azimuth of an object changes with time, as the object appears to drift across the sky. In addition, because the horizontal system is defined by the observer's local horizon, the same object viewed from different locations on Earth at the same time will have different values of altitude and azimuth."
"Horizontal coordinates are very useful for determining the rise and set times of an object in the sky. When an object's altitude is 0°, it is on the horizon. If at that moment its altitude is increasing, it is rising, but if its altitude is decreasing it is setting. However, all objects on the celestial sphere are subject to diurnal motion, which is always from east to west. One can determine whether altitude is increasing or decreasing by instead considering the azimuth of the celestial object:
- if the azimuth is between 0° and 180° (north–east–south), it is rising.
- if the azimuth is between 180° and 360° (south–west–north), it is setting.
There are the following special cases:
- At the north pole all directions are south, and at the south pole all directions are north, so the azimuth is undefined in both locations. A star (or any object with fixed equatorial coordinates) has constant altitude, and therefore never rises or sets when viewed from either pole. The Sun, Moon, and planets can rise or set over the span of a year when viewed from the poles because their right ascensions and declinations are constantly changing.
- At the equator objects on the celestial poles stay at fixed points on the horizon."
"Note that the above considerations are strictly speaking true for the geometric horizon only: the horizon as it would appear for an observer at sea level on a perfectly smooth Earth without an atmosphere. In practice the apparent horizon has a negative altitude, whose absolute value gets larger as the observer ascends higher above sea level, due to the curvature of the Earth. In addition, atmospheric refraction causes celestial objects very close to the horizon to appear about half a degree higher than they would if there were no atmosphere."
Geographic coordinate system
"A geographic coordinate system is a coordinate system that enables every location on the Earth to be specified by a set of numbers and/or letters. The coordinates are often chosen such that one of the numbers represents vertical position, and two or three of the numbers represent horizontal position. A common choice of coordinates is latitude, longitude and elevation."
"The latitude (abbreviation: Lat., φ, or phi) of a point on the Earth's surface is the angle between the equatorial plane and a line that passes through that point and is normal to the surface of a reference ellipsoid which approximates the shape of the Earth."
"This line passes a few kilometers away from the center of the Earth except at the poles and the equator where it passes through Earth's center."
"The greatest distance between an ellipsoid normal and the center of the Earth is 21.9 km at a latitude of 45°, using [the] [r]adius at a given geodetic latitude and [a] [c]omparison of selected types: (6367.5 km)×tan(11.67')=21.9 km."
"Lines joining points of the same latitude trace circles on the surface of the Earth called parallels, as they are parallel to the equator and to each other. The north pole is 90° N; the south pole is 90° S. The 0° parallel of latitude is designated the equator, the fundamental plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres."
"The [l]ongitude]] (abbreviation: Long., λ, or lambda) of a point on the Earth's surface is the angle east or west from a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses (often improperly called great circles), which converge at the north and south poles."
"A line passing near the Royal Observatory, Greenwich (near London in the UK) has been chosen as the international zero-longitude reference line, the Prime Meridian. Places to the east are in the eastern hemisphere, and places to the west are in the western hemisphere. The antipodal meridian of Greenwich is both 180°W and 180°E. The zero/zero point is located in the Gulf of Guinea about 625 km south of Tema, Ghana."
"[T]here exist organizations around the world which continue to use historical prime meridians which existed before the acceptance of Greenwich became common-place."
"This latitude/longitude "webbing" is known as the conjugate graticule."
"To completely specify a location of a topographical feature on, in, or above the Earth, one has to also specify the vertical distance from the centre of the Earth, or from the surface of the Earth. Because of the ambiguity of "surface" and "vertical", it is more commonly expressed relative to a precisely defined vertical datum which holds fixed some known point. Each country has defined its own datum. For example, in the United Kingdom the reference point is Newlyn, while in Canada, Mexico and the United States, the point is near Rimouski, Quebec, Canada. The distance to Earth's centre can be used both for very deep positions and for positions in space."
"The elevation of a geographic location is its height above a fixed reference ... geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see [g]eodetic system, vertical datum). Elevation, or geometric height, is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and depth is used for points below the surface."
Def. "[a]ny considerable and connected part of a space or surface; specifically, a tract of land or sea of considerable but indefinite extent; a country; a district; in a broad sense, a place without special reference to location or extent but viewed as an entity for geographical, social or cultural reasons" is called a region.
Regional astronomy is affected at least two different ways as a result of geography:
- variations in astronomical radiation regions as a result of geographic change in observatories and
- variations in geographical regions of observation as a result of change in astronomical radiation regions.
These variations are handled mathematically by ∂(radiation flux)/∂(location of observation) and ∂(location of observation)/∂(radiation flux). The former may occur as a solar flare passes close to the Earth. Those Earth observatory locations directly in the path have a different value of the radiation flux (depending on atmospheric effects) than those on the edge or outside the path of the flare. The latter may occur as the flux changes per a specific location, for example, with time of observation or energy of particles.
In the image at right Van Maanen's star is not at the center of the coordinates where expected, but as a high proper motion star it is actually off-center to the center top right. This is an example of the change in radiation flux to a specific location of observation by a source undergoing a change in location for observation (but staying within the observation field of view) within an observable change in radiation flux (the star did not move close enough to blacken the entire frame nor change intensity sufficiently to disappear into the background of the detector).
There is an “extensive 1/4 keV emission in the Galactic halo”, an “observed 1/4 keV [X-ray emission originating] in a Local Hot Bubble (LHB) that surrounds the Sun. ... and an isotropic extragalactic component.” In addition to this “distribution of emission responsible for the soft X-ray diffuse background (SXRB) ... there are the distinct enhancements of supernova remnants, superbubbles, and clusters of galaxies.”
"The ROSAT soft X-ray diffuse background (SXRB) image shows the general increase in intensity from the Galactic plane to the poles. At the lowest energies, 0.1 - 0.3 keV, nearly all of the observed soft X-ray background (SXRB) is thermal emission from ~106 K plasma."
A calendar is an astronomical radiation entity.
From the Ebers Papyrus, a year has 360 days of twelve months of thirty days each.
"All Veda [India] texts speak uniformly and exclusively of a year of 360 days [12 months of 30 days each]. Passages in which this length of the year is directly stated are found in all the Brahmanas." This period dates to approximately the third millennium (~5,000 b2k).
An ancient Chinese calendar had a 360 day year of twelve months of thirty days each.
The Mayans had an old tradition that the year had twelve months of thirty days each, 360 days in a year.
"The Peruvian year was divided into twelve Quilla, or moons, of thirty days."
Apparently, with each of these locations around the globe and several others near to the Mediterranean Sea, the year had exactly 360 days of 12 months of 30 days each, then at some point near 2700 b2k the year became lengthened to today's year.
Sources vary as does associated radiation.
"Air pollution [is] the release of chemicals and particulates into the atmosphere. Common gaseous pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs) and nitrogen oxides produced by industry and motor vehicles. Photochemical ozone and smog are created as nitrogen oxides and hydrocarbons react to sunlight. Particulate matter, or fine dust is characterized by their micrometre size PM10 to PM2.5."
The geography applicable to astronomy may be designated astrogeography. But, this term is often more restricted, as in "the relationship between outer-space geography and geographic position (astrogeography), and the evolution of current and future military space strategy" has been identified and evaluated.
Astronomy is performed all around the surface of the Earth by location. Astronomy on Earth is subject to local geography. Observatories on Earth occur at specific locations. The shapes and sizes, as well as functions, of particular observatories have changed over time, as have their altitude. To locate themselves on the surface of the Earth, various grid systems are devised using special points of reference. Each local center of civilization that realized the need for locating itself produced a system. One such system, the geographic coordinate system has based its locational grid on "[a] line passing near the Royal Observatory, Greenwich (near London in the UK).", from the Wikipedia article Royal Observatory, Greenwich. Another on French Institut Géographique National (IGN) maps still uses a longitude meridian passing through Paris, along with longitude from Greenwich.
The Atacama Large Millimeter/submillimeter Array (ALMA) is being constructed at an altitude of 5000 m on the Chajnantor plateau in the Atacama Desert of Chile. This is one of the driest places on Earth and this dryness, combined with the thin atmosphere at high altitude, offers superb conditions for observing the Universe at millimetre and submillimetre wavelengths. At these long wavelengths, astronomers can probe, for example, molecular clouds, which are dense regions of gas and dust where new stars are born when a cloud collapses under its own gravity. Currently, the Universe remains relatively unexplored at submillimetre wavelengths, so astronomers expect to uncover many new secrets about star formation, as well as the origins of galaxies and planets. From the Wikipedia article Atacama Large Millimeter Array: "ALMA began scientific observations in the second half of 2011 and the first images were released to the press on 3 October 2011. The project is scheduled to be fully operational by the end of 2012."
At times the location of the observatory is even more dramatically different as in the situation with Lunokhod-2 which is an X-ray observatory (X-ray telescope), carried to the Moon by Luna 21 to observe solar X-rays. Luna 21 landed on the Moon on January 15, 1973, at 22:35:00 UTC, latitude 25°51' N, longitude 30°27' E. Less than 3 hr later Lunokhod 2 disembarked onto the lunar surface at 01:14 UTC on January 16, 1973. While still near the Luna 21 platform Lunokhod 2 carried out solar X-ray studies.
The lower right image shows a neutron detector put into a pre-dug hole on the surface of the Moon by Eugene Cernan of the Apollo 17 lunar surface crew. Also, in the image is a boulder. "Now, this (boulder) ought to shield that thing (the neutron probe) from the doggone (RTG)" "[T]he neutron probe consists of targets containing either boron or uranium-235 which, upon capturing neutrons, emit alpha particles or fission fragments which are then captured by plastic or mica detectors. The instrument consists of an outer tube containing the detectors and a central core containing the targets. Because the targets and detectors do not cover the whole surfaces of the core and tube, respectively, the core can be twisted so that the target/detector pairs are either next to each other or 180 degrees apart. In the latter case, very few alpha particles or fission fragments are captured by the detectors and, therefore, the instrument is "off". "The neutron probe is a self-contained unit and, among other things, has no cable connecting it to electronics on the surface, a cable that would prevent the probe from falling out of reach to the bottom of the core hole. At the end of the third EVA, Jack will return to the ALSEP site and retrieve the probe so that he and Gene can bring it back to Earth for analysis."
The image at right is the Sudbury Neutrino Observatory. It is a 12-meter sphere filled with heavy water surrounded by light detectors located 2000 meters below the ground in Sudbury, Ontario, Canada.
"The Baksan Neutrino Observatory (BNO) ... consists of the Baksan Underground Scintillation Telescope, located 300m below the surface, a gallium–germanium neutrino telescope (the SAGE experiment) located 3,500m deep, as well as a number of ground facilities."
The Super-Kamiokande, or "Super-K" is a large-scale experiment constructed in an unused mine in Japan to detect and study neutrinos. Imaging the Sun required 500 days worth of data to produce the "neutrino image" of the Sun. The image is centered on the Sun's position. It covers a 90° x 90° octant of the sky (in right ascension and declination).
"The IceCube Neutrino Observatory (or simply IceCube) is a neutrino telescope constructed at the Amundsen-Scott South Pole Station in Antarctica. Similar to its predecessor, the Antarctic Muon And Neutrino Detector Array (AMANDA), IceCube contains thousands of spherical optical sensors called Digital Optical Modules (DOMs), each with a photomultiplier tube (PMT) and a single board data acquisition computer which sends digital data to the counting house on the surface above the array. IceCube was completed on 18 December, 2010, New Zealand time."
"Ice cores contain thin nitrate-rich layers that can be analyzed to reconstruct a history of past events before reliable observations; [this includes] data from Greenland ice cores and others. These show evidence that events of [the magnitude of the solar storm of 1859—as measured by high-energy proton radiation, not geomagnetic effect—occur approximately once per 500 years, with events at least one-fifth as large occurring several times per century. Less severe storms have occurred in 1921 and 1960, when widespread radio disruption was reported."
"ANTARES is the name of a neutrino detector residing 2.5 km under the Mediterranean Sea off the coast of Toulon, France. It is designed to be used as a directional Neutrino Telescope to locate and observe neutrino flux from cosmic origins in the direction of the Southern Hemisphere of the Earth, a complement to the southern hemisphere neutrino detector IceCube that detects neutrinos from the North."
"Apparent superluminal motion is observed in many radio galaxies, blazars, quasars and recently also in microquasars. The effect was [apparently] predicted before it was observed by Martin Rees ... and can be explained as an optical illusion caused by the object partly moving in the direction of the observer, when the speed calculations assume it does not. The phenomenon does not contradict the theory of special relativity. Interestingly, corrected calculations show these objects have velocities close to the speed of light (relative to our reference frame). They are the first examples of large amounts of mass moving at close to the speed of light. Earth-bound laboratories have only been able to accelerate small numbers of elementary particles to such speeds."
"The third largest solar proton event in the past thirty years took place during July 14-16, 2000, and had a significant impact on the earth's atmosphere."
"When we speak of the surface of the Sun, we normally mean the photosphere." "[T]he photosphere may be thought of as the imaginary surface from which the solar light that we see appears to be emitted. The diameter quoted for the Sun usually refers to the diameter of the photosphere."
Apparently 5102 b2k (before the year 2000.0), -3102 or 3102 BC, is the historical year assigned to a Hindu table of planets that does not include the classical planet Venus. "Vénus seule ne s'y trouvait pas." "Venus alone is not found there."
“That the planet Venus is missing will not startle anybody who knows the eminent importance of the four-planet system in the Babylonian astronomy” “Weidner supposes that Venus is missing in the list of planets because “she belongs to a triad with the moon and the sun.””
"[T]he Oh-My-God particle [was] observed on the evening of 15 October 1991 over Dugway Proving Ground, Utah. Its observation was a shock to astrophysicists, who estimated its energy to be approximately 3×1020
eV(50 joules)—in other words, a subatomic particle with kinetic energy equal to that of a baseball (142 g or 5 oz) traveling at 100 km/h (60 mph)."
"It was most probably a proton with a speed very close to the speed of light, so close, in fact, [(1 − 5×10−24
) × c], that in a year-long race between light and the cosmic ray, the ray would fall behind only 46 nanometers (5×10−24
light-years), or 0.15 femtoseconds (1.5×10−16
At right is a composite image which contains the first picture of the Earth in X-rays, taken in March, 1996, with the orbiting Polar satellite. Using an appropriate coordinate system, a diagram of the Earth below has been combined with the X-ray image. As an image resulting from X-ray emission by the ionosphere, this composite indicates that from X-ray astronomy the Earth is a gas dwarf.
At right is a geographic map of a region on the surface of the Moon. Red 21 is the landing place for Luna 21. Green 15 and 17 arrowheads indicate Apollo 15 and Apollo 17 landing locations.
The topographic map of Mars at right is "from the Mars Global Surveyor laser altimeter ... North is at the top. Notable features include the Tharsis volcanoes in the west (including Olympus Mons), Valles Marineris to the east of Tharsis, and Hellas Basin in the southern hemisphere."
"The geography of Mars, also known as areography, entails the delineation and characterization of regions on Mars. Martian geography is mainly focused on what is called physical geography on Earth; that is the distribution of physical features across Mars and their cartographic representations."
"On Oct 23, 2007, J. A. Henríquez Santana in the Canary Islands and Ramón Naves in Barcelona noticed an impressive spectacle, a bright and large comet gleemed through the bright full moon in the constellation Perseus."
Democritus "lived at Abdère 300 years before the Christian era [2300 b2k]. In a short fragment quoted by Plutarch, he declares that the Milky Way is an agglomeration of small stars too far away to be perceived singly."
In the artist's conception of the Milky Way at right is a grid over the concept. "The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, a primary direction aligned with the approximate center of the Milky Way galaxy, and a fundamental plane approximately in the galactic plane. It has a right-handed convention, meaning that coordinates are positive toward the north and toward the east in the fundamental plane."
Atmospheric Cherenkov telescopes
From the Wikipedia article on astronomy, "The Cherenkov telescopes do not actually detect the gamma rays directly but instead detect the flashes of visible light produced when gamma rays are absorbed by the Earth's atmosphere."
Converted Atmospheric Cherenkov Telescope Using Solar-2
Per the Wikipedia article about the Converted Atmospheric Cherenkov Telescope Using Solar-2 ground based Atmospheric Cherenkov Telescope (ACT), "The first astronomical observations started in the fall of 2004. However, the facility had its last observing runs in November 2005 as funds for observational operations from the National Science Foundation were no longer available."
CACTUS is sensitive in the 50-500 GeV energy range.
"The CACTUS atmospheric Cherenkov telescope collaboration recently reported a gamma-ray excess from the Draco dwarf spheroidal galaxy." "[T]he bulk of the signal detected by CACTUS [may come] from direct [weakly interacting massive particles (WIMPs)] WIMP annihilation to two photons".
"HEGRA, which stands for High-Energy-Gamma-Ray Astronomy, was an atmospheric Cherenkov telescope for Gamma-ray astronomy. With its various types of detectors, HEGRA took data between 1987 and 2002, at which point it was dismantled in order to build its successor, MAGIC, at the same site." per the Wikipedia article on the HEGRA atmospheric Cherenkov telescope. HEGRA is at 2200 masl.
High Energy Stereoscopic System
From the Wikipedia article high energy stereoscopic system (HESS): "High Energy Stereoscopic System or H.E.S.S. is a next-generation system of Imaging Atmospheric Cherenkov Telescopes (IACT) for the investigation of cosmic gamma rays in the 100 GeV and TeV energy range. The acronym was chosen in honour of Victor Hess, who was the first to observe cosmic rays.
The name also emphasizes two main features of the currently-operating installation, namely the simultaneous observation of air showers with several telescopes, under different viewing angles, and the combination of telescopes to a large system to increase the effective detection area for gamma rays. H.E.S.S. permits the exploration of gamma-ray sources with intensities at a level of a few thousandth parts of the flux of the Crab Nebula.
H.E.S.S. is located on the Cranz family farm, Göllschau, in Namibia, near the Gamsberg, an area well known for its excellent optical quality. The first of the four telescopes of Phase I of the H.E.S.S. project went into operation in Summer 2002; all four were operational in December 2003."
Major Atmospheric Gamma-ray Imaging Cherenkov Telescopes
"MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov Telescopes) is a system of two Imaging Atmospheric Cherenkov telescopes situated at the Roque de los Muchachos Observatory on [La Palma, one of the Canary Islands, at about 2200 m above sea level. MAGIC detects particle showers released by gamma rays, using the Cherenkov radiation, i.e., faint light radiated by the charged particles in the showers. With a diameter of 17 meters for the reflecting surface, it is the largest in the world. ... MAGIC is sensitive to cosmic gamma rays with energies between 50 GeV and 30 TeV due to its large mirror; other ground-based gamma-ray telescopes typically observe gamma energies above 200-300 GeV. Satellite-based detectors detect gamma-rays in the energy range from keV up to several GeV. ... MAGIC has found pulsed gamma-rays at energies higher than 25 GeV coming from the Crab Pulsar. The presence of such high energies indicates that the gamma-ray source is far out in the pulsar's magnetosphere, in contradiction with many models. ... A much more controversial observation is an energy dependence in the speed of light of cosmic rays coming from a short burst of the blazar Markarian 501 on July 9, 2005. Photons with energies between 1.2 and 10 TeV arrived 4 minutes after those in a band between .25 and .6 TeV. The average delay was .030±.012 seconds per GeV of energy of the photon. If the relation between the space velocity of a photon and its energy is linear, then this translates into the fractional difference in the speed of light being equal to minus the photon's energy divided by 2 x 017 GeV." per the Wikipedia article on the Major Atmospheric Gamma-ray Imaging Cherenkov Telescopes.
Solar Tower Atmospheric Cherenkov Effect Experiment
Per the Wikipedia article on the Solar Tower Atmospheric Cherenkov Effect Experiment, "The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), is a gamma ray detector located near Albuquerque, New Mexico. Observations with STACEE began in October 2001 and concluded in June 2007. Gamma rays were observed from objects such as the Crab Nebula, a supernova remnant, and Markarian 421, a blazar. STACEE uses the heliostats and space on the receiver tower of the National Solar Thermal Test Facility operated by the Sandia National Laboratories on the grounds of the Kirtland Air Force Base. ... During the night STACEE uses the heliostats to reflect the brief flashes of Cerenkov radiation caused by gamma rays hitting the upper atmosphere to photodetectors mounted in the tower. STACEE is a nonimaging telescope, meaning that it detects the light from a portion of the sky, but does not resolve the light into an image."
“The Great Pyramid stands on the northern edge of the Giza Plateau, [60.4 m] 198 feet above sea level”. From the Wikipedia article Archaeoastronomy, “Since the first modern measurements of the precise cardinal orientations of the pyramids by Flinders Petrie, various astronomical methods have been proposed for the original establishment of these orientations. It was recently proposed that this was done by observing the positions of two stars in the Plough / Big Dipper which was known to Egyptians as the thigh. It is thought that a vertical alignment between these two stars checked with a plumb bob was used to ascertain where North lay. The deviations from true North using this model reflect the accepted dates of construction. Some have argued that the pyramids were laid out as a map of the three stars in the belt of Orion, although this theory has been criticized by reputable astronomers.”
The Tuorla Observatory, in Tuorla, Finland, is “needed because the old Iso-Heikkilä Observatory close to the centre of Turku started suffering heavy light pollution from [the] nearby city and especially industrial areas to the south of the observatory. ... [It] is located about 12 kilometres from Turku in the direction of Helsinki. ... The first part of the observatory contained a main building and [a] 51 meter long tunnel for optical research. ... The optical laboratory produces high quality optics for telescopes.” The observatory is at an altitude of 60.6 m above sea level (asl). The tower is part of the structure to put the 1.0 m telescope above the tops of local trees rather than cutting the trees down.
From the Wikipedia article Aldershot, “The town is generally between 70 m and 100 m above sea level.”
“The location of the observatory can hardly be considered ideal for astronomical observations, even at the time of its construction. It is at a low elevation in an essentially urban setting of an army town with many nearby buildings that date from the time of its construction. It is very near a road that is lit by streetlights, although this was somewhat ameliorated by a clockwork switch inside the observatory that would turn off the nearest streetlights for about 20 minutes. This clockwork system was upgraded in 1987. As the electricity supply has been removed in 2006, this facility is no longer available. ... In its current location, the observatory will be an island in a sea of houses and some people fear that it will be targeted by vandals or, perhaps, will have to be protected with high, unsightly fences.”, per Wikipedia Aldershot Observatory.
From the Wikipedia article on Stonehenge, “Whatever religious, mystical or spiritual elements were central to Stonehenge, its design includes a celestial observatory function, which might have allowed prediction of eclipse, solstice, equinox and other celestial events important to a contemporary religion.”
“Stonehenge does not occupy a topographic high, but rather a site of intermediate elevation, such that the natural horizon, when viewed from the heel stone, is remarkably even and is sufficiently far away that its elevation above the astronomical horizon is a small angle.”
“All results were registered by Professor Gowland in relation to a datum line [102.8 m] 337.4 feet above sea level.”
National Observatory of Athens
The National Observatory of Athens is 107 m asl. It is on top of Nymphs' Hill. "The cross-like neoclassic building has its sides oriented toward the four directions of the horizon. There is a small dome for a telescope in the center of the construction."
Merate Astronomical Observatory
"Starting from the end 19th century light pollution from Milan disturbed the activities of the Brera astronomical observatory. ... Today Brianza is one of the most densely populated regions of Italy and the light pollution is considerable. Nonetheless, the observatory is still used for research activities (leader in the production of X-Ray optics), as well as course- and thesis-work for the students of Milan University."
The Merate Astronomical Observatory is at 292 m elevation.
Mauna Kea Observatory
"The Canada-France-Hawaii Telescope (CFHT) is a 3.6 m optical-infrared telescope located on the summit of Mauna Kea on the island of Hawaii." From the Wikipedia article Canada-France-Hawaii Telescope: the CFHT is "at an altitude of 4,204 meters". "Mauna Kea last erupted 4,000 to 6,000 years ago [~7,000 b2k].", from the Wikipedia article and "The Mauna Kea Observatories are used for scientific research across the electromagnetic spectrum from visible light to radio, and comprise the largest such facility in the world."
"The ideal submillimetre observing site is dry, cool, has stable weather conditions and is away from urban population centres. There are only a handful of such sites identified, they include Mauna Kea (Hawaii, USA), the Llano de Chajnantor Observatory on the Atacama Plateau (Chile), the South Pole, and Hanla (India). Comparisons show that all four sites are excellent for submillimetre astronomy, and of these sites Mauna Kea is the most established and arguably the most accessible. The Llano de Chajnantor Observatory site hosts the Atacama Pathfinder Experiment (APEX), the largest submillimetre telescope operating in the southern hemisphere, and the world's largest ground based astronomy project, the Atacama Large Millimeter Array (ALMA), an interferometer for submillimetre wavelength observations made of 54 12-metre and 12 7-metre radio telescopes. The Submillimeter Array (SMA) is another interferometer, located at Mauna Kea, consisting of eight 6-metre diameter radio telescopes. The largest existing submillimetre telescope, the James Clerk Maxwell Telescope, is also located on Mauna Kea." per the Wikipedia article submillimeter astronomy.
“The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a submillimeter telescope that hangs from a high altitude balloon. It has a 2 meter primary mirror that directs light into bolometer arrays operating at 250, 350, and 500 µm."
"On June 19, 1988, from Birigüi (50° 20' W 21° 20' S) at 10:15 UTC a balloon launch occurred which carried two NaI(Tl) detectors (600 cm2 total area) to an air pressure altitude of 5.5 mb for a total observation time of 6 hr. The supernova SN1987A in the Large Magellanic Cloud (LMC) was discovered on February 23, 1987, and its progenitor is a blue supergiant (Sk -69 202) with luminosity of 2-5 x 1038 erg/s. The 847 keV and 1238 keV gamma-ray lines from 56Co decay have been detected."
"The Antarctic Impulsive Transient Antenna (ANITA) experiment has been designed to study ultra-high-energy (UHE) cosmic neutrinos by detecting the radio pulses emitted by their interacting with the Antarctic ice sheet. This is to be accomplished using an array of 32 radio antennas (cylindrically arranged with an approximate radius of 3m and a height of 5m) suspended from a helium balloon flying at a height of about 35,000 meters. The neutrinos, with energies on the order of 1018 eV, produce radio pulses in the ice because of the Askaryan effect."
Measurements "of the cosmic-ray positron fraction as a function of energy have been made using the High-Energy Antimatter Telescope (HEAT) balloon-borne instrument."
"The first flight took place from Fort Sumner, New Mexico, [on May 3, 1994, with a total time at float altitude of 29.5 hr and a mean atmospheric overburden of 5.7 g cm-2] ... The second flight [is] from Lynn Lake, Manitoba, [on August 23, 1995, with a total time at float altitude of 26 hr, and a mean atmospheric overburden of 4.8 g cm-2]".
For possibly locating X-ray sources above the Earth's atmosphere, there are a number of reasons to consider probing from different geographical locations:
- early visual observations of the solar corona are associated with eclipses of the Sun by the Moon,
- if the Sun is an X-ray source, then perhaps other stars are, and only so many can be observed from one location,
- laboratory measurements use a peak of intensity to background (possible unknown sources) technique which demands measuring an X-ray background noise, and
- there may be X-ray scattering by the Earth's upper atmosphere.
Observatories on the Earth's surface do not seem like a useful place to conduct X-ray astronomy observations in view of the inability of X-rays to reach even the peaks of the highest mountains. From the earliest speculations about detecting X-rays above the Earth's atmosphere, the need to use an appropriate probe suggested a high altitude sounding rocket. The ending of World War II presented an opportunity to use a ballistic missile for just such a purpose. The White Sands Proving Grounds in New Mexico, at the time an army base, is the first location on land to test the concept. The image at the right shows the V-2 launch complex prior to the launch of V-2 number 6.
The first successful attempt to detect X-rays above the Earth's surface occurred at White Sands Proving Grounds on August 5, 1948, by lofting an X-ray detector with a V-2 rocket.
As with visual or optical astronomy observatories, there is a tendency to place them away from population centers. The photograph at right of the January 18, 1951, V-2 launch indicates one reason for doing so with X-ray observing. Rockets lofted upwards tend to return.
In the southern hemisphere at Woomera, South Australia, another X-ray observing location uses a famous and probably the most successful sounding rocket, the Skylark, to place X-ray detectors at suborbital altitudes. "[T]he first X-ray surveys of the sky in the Southern Hemisphere" are accomplished by Skylark launches.
The NRL and NASA establish another rocket launching facility outside Natal, Brazil to detect X-ray sources in the southern hemisphere. In addition to land-based surface launches of sounding rockets for X-ray detection, occasionally ocean surface ships served as stable platforms. The USS Point Defiance (LSD-31) is one of the first rocket-launching surface ships to support the 1958 IGY Solar Eclipse Expedition to the Danger Island region of the South Pacific. Launchers on deck fired eight Nike-Asp sounding rockets. Each rocket carried an X-ray detector to record X-ray emission from the Sun during the solar eclipse on October 12, 1958.
At right is a north oriented, land/water map of the orbital rocketry launch facilities on Merritt Island, Florida, USA. Latitude 28°29'20"N and longitude 80°34'40"W are the geographic coordinates for the Cape Canaveral Air Force Station colored green.
The headquarters for the Kennedy Space Center, in white, is located at 28°31'26.608"N 80°39'3.055"W.
"The Xichang Satellite Launch Center (XSLC) is a People’s Republic of China space vehicle launch facility (spaceport) approximately 64 km northwest of Xichang, Liangshan Yi Autonomous Prefecture in Sichuan."
"The Thumba Equatorial Rocket Launching Station (TERLS) is an Indian spaceport operated by the Indian Space Research Organization. It is located in Thumba, Thiruvananthapuram which is near the southern tip of India, very close to earth's magnetic equator. It currently used by ISRO for launching sounding rockets."
Thumba is located very close the magnetic equator of the Earth (located just north of Thumba), making it the ideal location for scientists to conduct atmospheric research. In fact, Thumba's location at 8°32'34" N and 76°51'32" E is ideal for low-altitude, upper atmosphere and ionosphere studies."
Astrophysical radiation geography
A number of physics laboratories and facilities worldwide have been and are being used to understand the observations made using radiation astronomy. Some of these include Fermilab, the Lawrence Livermore National Laboratory, the Los Alamos National Laboratory, and the Stanford Linear Accelerator Center in the USA.
Fermi National Accelerator Laboratory
From the Wikipedia article on Fermilab: "Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics."
"In addition to high energy collider physics, Fermilab is also host to a number of smaller fixed-target and neutrino experiments, such as MiniBooNE (Mini Booster Neutrino Experiment), SciBooNE (SciBar Booster Neutrino Experiment) and MINOS (Main Injector Neutrino Oscillation Search). The MiniBooNE detector is a 40-foot (12 m) diameter sphere which contains 800 tons of mineral oil lined with 1520 individual phototube detectors. An estimated 1 million neutrino events are recorded each year. SciBooNE is the newest neutrino experiment at Fermilab; it sits in the same neutrino beam as MiniBooNE but has fine-grained tracking capabilities. The MINOS experiment uses Fermilab's NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota." per Fermilab.
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