Methods
The methods used to perform photometry depend on the wavelength regime under study. At its most basic, photometry is conducted by gathering radiation in a telescope, perhaps passing it through specialized optical filters, and then capturing and recording the light energy with a photosensitive instrument. The set of passbands (filters) is called a photometric system.
Historically, photometry in the near infrared through long-wavelength ultra-violet 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 which can simultaneously image multiple objects, though photoelectric photometers are still used in special situations, such as where high time resolution is required.
Read more about this topic: Photometry (astronomy)
Famous quotes containing the word methods:
“All good conversation, manners, and action, come from a spontaneity which forgets usages, and makes the moment great. Nature hates calculators; her methods are saltatory and impulsive.”
—Ralph Waldo Emerson (1803–1882)
“If men got pregnant, there would be safe, reliable methods of birth control. They’d be inexpensive, too.”
—Anna Quindlen (b. 1952)
“In inner-party politics, these methods lead, as we shall yet see, to this: the party organization substitutes itself for the party, the central committee substitutes itself for the organization, and, finally, a “dictator” substitutes himself for the central committee.”
—Leon Trotsky (1879–1940)