International Astronomical Union

Photometry is the accurate measurement of the apparent magnitude of an astronomical object. Magnitudes obtained always occur with respect to a few wavelengths or spectral bands. G: parameter used to calculate the apparent magnitude of an asteroid with the new calculation system, and which replaces the phase coefficient. geocentric, distance, d: distance from the Earth to the asteroid. H: absolute magnitude. heliocentric, distance, r: distance between Sun and the celestial object. Hildas: class of asteroids with resonance of 2/3. IAU: International Astronomical Union, founded in 1919. tilt, i: angle formed between the orbit of the asteroid and the plane of the ecliptic. colour index: the difference in magnitudes between any two spectral bands. JD: Julian day number, is the number of days that have elapsed since Greenwich mean time from January 1, 4713 AC. Kirkwood, empty of: empty belt asteroid where the orbital periods of asteroids correspond to certain fractions of the Jupiter period. Langranianos, points: five points in the orbital plane of two massive bodies in circular orbit around a center of gravity common, where a third body can stay in balance. libration: angular motion around the center of mass of a celestial body. longitude of the ascending node: angular distance measured from the vernal equinox eastward in the plane of the orbit of the Earth to the point where the asteroid crosses the ecliptic from S to N. perihelion length: the sum of argument you of perihelion and longitude of the ascending node. Note that it is the sum of two angles that are in different planes. Mars crosser: asteroids that cross the orbit of Mars, about 1.5 U.A. magnetite: opaque mineral commonly found in asteroids type C.