Photom is photometric package based on Sextrator. It allows to create master images for calibration, photometric reduction, photometry and identification of the object on the CCD frames as well as variable stars detection.
Photometry deals with light energy of wavelengths that can cause visual sensation. The human visual range is typically from 380nm to 780nm. Wavelengths outside this range do very little in stimulating our eye.
The measurement of the visual aspect of radiant energy ( light). As such, it is distinguished from radiometry in that photometry takes into account the varying sensitivity of the eye to different wavelengths of light.
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.