Apparent Grade
Apparent grade or conduct grade, Annish grade is a unit to measure the brightness of a star. The astronomer Hipparchus distinguishes the brightest stars as the first class, and the darkest stars as the sixth class. And by the 19th century, Foggson of England had used a light measuring device to find out that the brightness of a first class star is about 100 times the brightness of a sixth class star. Based on this, in modern astronomy, grade 6 is defined 100 times darker than grade 1. That is, the second grade stars are 1001/5 = about 2,512 times darker than the first grade stars. The absolute grade is the original brightness of the star, and is the brightness assuming it is placed at a distance of 10 parsec from the Earth. For example, the absolute grade of the Sun is 4.8, and the apparent grade is -26.8. There is a relationship between the apparent magnitude and the absolute magnitude of the celestial body at the Pacek distance from Earth.