High Quality Content by WIKIPEDIA articles! 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.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.