The Apollo Group Asteroid 2008 OS9: Discovery, Orbit, Rotation and the Yarkovsky/YORP Effects

Abstract

Abstract A project for astrometric and photometric observations of asteroids at the Baldone Observatory is described. One of the most important results of the project is the discovery of 2008 OS9, a 600 meter asteroid of the NEO Apollo group. The results of its astrometric and photometric observations at the Molėtai and Baldone observatories are presented. From the brightness variation with the 0.27 mag amplitude, a rotation period of 8.430 ± 0.005 h is determined. Close approaches of the asteroid to Earth and Venus during the next millenium are predicted. The mean values of secular changes in the semi-major axis, eccentricity and inclination are computed with and without the Yarkovsky and YORP effects. A negative value of the difference between the value of semi-major axis computed with the Yarkovsky and YORP effects and without them, da/dt, may indicate retrograde rotation of the asteroid.