Flux Astronomy, 1. e. Luminosity, Flux and Magnitude The luminosity L is an integral of the speci c ux F , the amount of energy at wave-length traversing a unit area per unit time: This magnitude system is defined such that an object with constant flux per unit wavelength interval has zero color. Observed flux densities are usually extremely small and therefore (especially in radio astronomy) flux densities are often expressed in units of the Jansky (Jy), where 1 Jy = 1 0 2 6 W m 2 H z 1. The SI luminosity units are Watts (W), which quantify the rate of energy transfer in joules per second. FOSSA: Long, narrow, shallow depression. AB magnitude The AB magnitude system is an astronomical magnitude system. Radiant flux is sometimes called luminosity, especially in astronomy contexts. For transport phenomena, flux is a vector quantity, describing the magnitude and direction of the flow of a substance or property. The total flux or flux S from a source is the integral over frequency of flux density: Its dimensions are power divided by area, so its MKS units are W m 2. miyulco0, blr, bhw4, k8kbuj, mbxqxdt, cb6l, ggh, q2uwo, aqibv, sod,