noun
: the observed or apparent brightness of a celestial body expressed on the magnitude scale and varying in accordance with the spectral sensitivity of the means of observing (as the eye, a photographic material, or an instrument)
noun
: the observed or apparent brightness of a celestial body expressed on the magnitude scale and varying in accordance with the spectral sensitivity of the means of observing (as the eye, a photographic material, or an instrument)
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012