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Encyclopedia > Photometry (astronomy)

Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation. Usually, photometry refers to measurement over large wavelength bands of radiation; but, when not only the amount of radiation but its spectral distribution are measured the term spectrophotometry is used. When the distance of the measured object can be estimated, photometry can give information about the total energy emitted by the object, its size, its temperature and other physical properties. Accurate photometry is more difficult when the apparent brightness of the object is fainter. Astronomy is one of the few sciences where amateurs can still play an active role, especially in the discovery and monitoring of transient phenomena. ... In classical physics and engineering, measurement is the the result of comparing physical quantities of objects, relations (e. ... The flux visualized. ... See lists of astronomical objects for a list of the various lists of astronomical objects in Wikipedia. ... Electromagnetic radiation is a propagating wave in space with electric and magnetic components. ... The wavelength is the distance between repeating units of a wave pattern. ... Radiation generally means the transmission of waves, objects or information from a source into a surrounding medium or destination. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ...


Historically photometry was done with a photoelectric photometer, an instrument that measured the light intensity of a single object by directing its light on to a photosensitive cell. They have largely been replaced with CCD cameras, though photoelectric photometers are still used in special situations, such as where high time resolution is required. A charge-coupled device (CCD) is a sensor for recording images, consisting of an integrated circuit containing an array of linked, or coupled, capacitors. ...


At its most basic, photometry is conducted by gathering light in an optical telescope, passing the light through specialized optical filters, and then capturing the light energy on a CCD. Generally at least three different photometric images are taken, as well as images of photometric standard stars, each using different filters; and the data is then used to calculate physical and chemical parameters of the object. Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye, or in a more general sense, any electromagnetic radiation in the range from infrared to ultraviolet. ... An optical telescope is a telescope which is used to gather, and focus, light, for directly viewing a magnified image, making a photograph, etc. ... An optical filter is a device which selectively transmits light having certain properties (often, a particular range of wavelengths, i. ... A charge-coupled device (CCD) is a sensor for recording images, consisting of an integrated circuit containing an array of linked, or coupled, capacitors. ... Photometric standard stars are a series of stars that have had their light output in various passbands measured very carefully. ... A datum is a statement accepted at face value (a given). Data is the plural of datum. ...


Photometry is generally used to generate light curves of objects such as variable stars and supernova where the quantity of interest is the variation of total light energy output over time. Photometry can be used as a technique to discover exoplanets. By measuring the intensity of a star's light over a period of time, astronomers can examine deviations in its spectral output and determine possible causes. In astronomy, a light curve is a graph of light intensity as a function of time. ... Most stars are of nearly constant luminosity. ... Infrared image of the star GQ Lupi (A) orbited by a planet (b) at a distance of approximately 20 times the distance between Jupiter and our Sun. ... Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye, or in a more general sense, any electromagnetic radiation in the range from infrared to ultraviolet. ...


See also


  Results from FactBites:
 
Photometry (astronomy) - Wikipedia, the free encyclopedia (334 words)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation.
Historically photometry was done with a photoelectric photometer, an instrument that measured the light intensity of a single object by directing its light on to a photosensitive cell.
Photometry is generally used to generate light curves of objects such as variable stars and supernova where the quantity of interest is the variation of total light energy output over time.
  More results at FactBites »

 
 

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