Asteroids absolute colors and phase coeff.

Although we can observe asteroids up to phase angles of about 30deg, the range of phase angles covered by outer solar system objects usually does not go further than 7 to 10deg for centaurs and 2deg for trans-Neptunian objects, and a linear relation between magnitude and phase angle may be assumed.

We aim at directly comparing data taken for objects in the inner solar system (inside the orbit of Jupiter) with data of centaurs and trans-Neptunian objects. We use the SLOAN Moving Objects Catalog data to construct phase curves restricted to phase angles less than or equal to 7.5deg, compatible with the angles observed for the trans-Neptunian/Centaur population. We assume a linear model for the photometric behavior to obtain absolute magnitudes and phase coefficients in the ugirz, V, and R filters.