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Limiting Magnitude
In astronomy, limiting magnitude is the faintest apparent magnitude of a celestial body that is detectable or detected by a given instrument. In some cases, limiting magnitude refers to the upper threshold of detection. In more formal uses, limiting magnitude is specified along with the strength of the signal (e.g., "10th magnitude at 20 sigma"). Sometimes limiting magnitude is qualified by the purpose of the instrument (e.g., "10th magnitude for photometry") This statement recognizes that a photometric detector can detect light far fainter than it can reliably measure. The limiting magnitude of an instrument is often cited for ideal conditions, but environmental conditions impose further practical limits. These include weather, moonlight, skyglow, and light pollution. The International Dark-Sky Association has been vocal in championing the cause of reducing skyglow and light pollution. Naked-eye visibility The limiting magnitude for naked eye visibility refers to the fai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomy
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole. Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Babylonians, Greeks, Indians, Egyptians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Night Sky
The night sky is the nighttime appearance of astronomical object, celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include moonlight, starlight, and airglow, depending on location and timing. Aurorae light up the skies above the polar circles. Occasionally, a large coronal mass ejection from the Sun or simply high levels of solar wind may extend the phenomenon toward the Equator. The night sky and studies of it have a historical place in both ancient and modern cultures. In the past, for instance, farmers have used the status of the night sky as a calendar to determine when to agriculture, plant crops. Many cultures have drawn constellations between stars in the sky, using them in association with legends and mythology about their deity, deities. The history of astrology, anciently developed belief of astrology is generally based on the bel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Araucaria Project
The Araucaria Project is an international science collaboration focused on improving the calibration of the extragalactic distance scale based on observations of major distance indicators in several nearby galaxies. Project The Araucaria Project is a collaboration between astronomers from institutions in Europe, Chile and the US. Its principal aim is to provide an improved calibration of the local extragalactic distance scale. In the process of setting up the extragalactic distance scale, the greatest difficulty leading to the currently largest contribution on the systematic uncertainty of the Hubble constant lies in the determination of accurate absolute distances to nearby galaxies. The principal reason for this persisting difficulty is in the unknown dependencies of stellar standard candles, used to measure the distances of nearby galaxies, on the environmental properties of their host galaxies (metallicity, age of the stellar populations etc.). The Araucaria Project is an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz). Longer IR wavelengths (30 μm-100 μm) are sometimes included as part of the terahertz radiation range. Almost all black-body radiation from objects near room temperature is at infrared wavelengths. As a form of electromagnetic radiation, IR propagates energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon. It was long known that fires emit invisible heat; in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat. In 1800 the astronomer Sir William Herschel discove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
James Webb Space Telescope
The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Space Telescope. This will enable investigations across many fields of astronomy and cosmology, such as observation of the first stars, the formation of the first galaxies, and detailed atmospheric characterization of potentially habitable exoplanets. The U.S. National Aeronautics and Space Administration (NASA) led JWST's design and development and partnered with two main agencies: the European Space Agency (ESA) and the Canadian Space Agency (CSA). The NASA Goddard Space Flight Center (GSFC) in Maryland managed telescope development, the Space Telescope Science Institute in Baltimore on the Homewood Campus of Johns Hopkins University operates JWST, and the prime contractor was Northrop Grumman. The telescope is named after James E. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zodiacal Light
The zodiacal light (also called false dawn when seen before sunrise) is a faint glow of diffuse sunlight scattered by interplanetary dust. Brighter around the Sun, it appears in a particularly dark night sky to extend from the Sun's direction in a roughly triangular shape along the zodiac, and appears with less intensity and visibility along the whole ecliptic as the zodiacal band. Zodiacal light spans the entire sky and contributes to the natural light of a clear and moonless night sky. A related phenomenon is ''gegenschein'' (or ''counterglow''), sunlight backscattered from the interplanetary dust, appearing directly opposite to the Sun as a faint but slightly brighter oval glow. Zodiacal light is very faint, often outshined and rendered invisible by moonlight or light pollution. The interplanetary dust in the Solar System forms a thick, pancake-shaped cloud called the zodiacal cloud which straddles the ecliptic plane. The particle sizes range from 10 to 300 microme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft. Hubble features a mirror, and its five main instruments observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. Hubble's orbit outside the distortion of Earth's atmosphere allows it to capture extremely high-resolution images with substantially lower background light than ground-based telescopes. It has recorded some of the most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pan-STARRS
The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1; obs. code: F51 and Pan-STARRS2 obs. code: F52) located at Haleakala Observatory, Hawaii, US, consists of astronomical cameras, telescopes and a computing facility that is surveying the sky for moving or variable objects on a continual basis, and also producing accurate astrometry and photometry of already-detected objects. In January 2019 the second Pan-STARRS data release was announced. At 1.6 petabytes, it is the largest volume of astronomical data ever released. Description The Pan-STARRS Project is a collaboration between the University of Hawaii Institute for Astronomy, MIT Lincoln Laboratory, Maui High Performance Computing Center and Science Applications International Corporation. Telescope construction was funded by the U.S. Air Force. By detecting differences from previous observations of the same areas of the sky, Pan-STARRS is discovering many new asteroids, comets, variable stars, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zwicky Transient Facility
The Zwicky Transient Facility (ZTF, obs. code: I41) is a wide-field sky astronomical survey using a new camera attached to the Samuel Oschin Telescope at the Palomar Observatory in California, United States. Commissioned in 2018, it supersedes the (Intermediate) Palomar Transient Factory (2009–2017) that used the same observatory code. It is named after the astronomer Fritz Zwicky. Description Observing in visible and infra-red wavelengths, the Zwicky Transient Facility is designed to detect transient objects that rapidly change in brightness, for example supernovae, gamma ray bursts, and collision between two neutron stars, and moving objects like comets and asteroids. The new camera is made up of 16 CCDs of 6144×6160 pixels each, enabling each exposure to cover an area of 47 square degrees. The Zwicky Transient Facility is designed to image the entire northern sky in three nights and scan the plane of the Milky Way twice each night to a limiting magnitude of 20.5 (r b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalina Sky Survey
Catalina Sky Survey (CSS; obs. code: 703) is an astronomical survey to discover comets and asteroids. It is conducted at the Steward Observatory's Catalina Station, located near Tucson, Arizona, in the United States. CSS focuses on the search for near-Earth objects, in particular on any potentially hazardous asteroid that may pose a threat of impact. Its counterpart in the southern hemisphere was the Siding Spring Survey (SSS), closed in 2013 due to loss of funding. CSS supersedes the photographic Bigelow Sky Survey. Mission The NEO Observations Program is a result of a United States 1998 congressional directive to NASA to begin a program to identify 1 kilometre (0.62 mile) or larger objects to around 90 percent confidence level or better. The Catalina Sky Survey, located at the Mount Lemmon Observatory in the Catalina Mountains north of Tucson, carries out searches for near-earth objects, NEOs, contributing to the congressionally mandated goal. In addition to identif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure Time
In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light (that is, when the camera's shutter is open) when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time. of a second will let half as much light in as . Introduction The camera's shutter speed, the lens's aperture or f-stop, and the scene's luminance together determine the amount of light that reaches the film or sensor (the exposure). Exposure value (EV) is a quantity that accounts for the shutter speed and the f-number. Once the sensitivity to light of the recording surface (either film or sensor) is set in numbers expressed in " ISOs" (ex: 200 ISO, 400 ISO), the light emitted by the scene photographed can be controlled through aperture and shutter-speed to match the film or sensor sensitivity to light. This will achieve a good exposure when all the details of the scene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
