Glossary term: Photometry

Description: The term photometry is derived from the Greek phōs meaning light, and metro meaning to measure. Although there are various types of photometry, the basic method involves measuring the intensity of the light (photons) radiated by various astronomical objects. The light from objects passes through specialized filters (known as passbands), and that light is captured on a digital device such as a camera CCD. Separate passbands cover ranges of wavelengths, that may include infrared, visible, and ultraviolet. Astronomical telescopes often have filter groups, which are called photometric systems. Some common systems include UBVRI, JHK, and ugriz. Photometry allows different physical characteristics of astronomical objects to be measured, for example, temperature, color, and change in brightness.

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