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:
“How can you tell if you discipline effectively? Ask yourself if your disciplinary methods generally produce lasting results in a manner you find acceptable. Whether your philosophy is democratic or autocratic, whatever techniques you use—reasoning, a “star” chart, time-outs, or spanking—if it doesn’t work, it’s not effective.”
—Stanley Turecki (20th century)
“Parents ought, through their own behavior and the values by which they live, to provide direction for their children. But they need to rid themselves of the idea that there are surefire methods which, when well applied, will produce certain predictable results. Whatever we do with and for our children ought to flow from our understanding of and our feelings for the particular situation and the relation we wish to exist between us and our child.”
—Bruno Bettelheim (20th century)
“It would be some advantage to live a primitive and frontier life, though in the midst of an outward civilization, if only to learn what are the gross necessaries of life and what methods have been taken to obtain them.”
—Henry David Thoreau (1817–1862)