A measure of the brightness or luminosity of a star or other celestial object: The larger the number referring to the magnitude, the fainter the object.

Zero, or first magnitude, indicates some of the brightest stars.

Still brighter are those of negative magnitude, such as Sirius, whose magnitude is -1.46.

The magnitude a celestial object would appear to have if it were at a distance of ten parsecs (10 times 3.261633 light years or 32.62 parsecs): The absolute magnitude is the measure of the true or intrinsic brightness of a star as if all stars were the same distance (32.6 light-years) from the observer.

The absolute magnitude of an object measured through a special yellowish filter that approximates the visual range of the human eye: For stars, a normally cited absolute magnitude is the absolute visual magnitude that uses the visual (V) band of the spectrum.

A numerical assessment of the brightness of a heavenly body: An apparent is the intensity of light of a star as seen from the planet Earth.

3. An apparent is the numeric calculation of the luminosity of stars as they appear on the celestial sphere.