CCD photometry of the MUSES-C mission target: Asteroid (25143) 1998 SF36

Near-Earth asteroid (25143) 1998 SF36 is now planned as the target for the Japanese MUSES-C sample return mission. We conducted extensive photometric observations at NAO-Mitaka from 2001 February 15 until March 19 to obtain its physical properties, such as asteroid's colors, rotation period, phase curve, and light curves. The colors of this asteroid were found to be S-type and in agreement with the spectroscopic result by Binzel et al. (2001, Meteor. Planet. Sci., 36, 1167). From the phase curve of this object, the visual absolute magnitude is obtained to be 18.61 +/- 0.18; we suggest that the albedo may be higher than that for typical S-type asteroids, after applying a known empirical relation between phase curve slope and geometric albedo. We also reveal that the synodic rotation period of this asteroid is 12.13 +/- 0.02hr and the peak-to-peak light variation amplitude at zero phase angle has been shown to be similar to 0.49 mag, which implies the ratio of the longest and intermediate ellipsoidal axes for the asteroid greater than or similar to 1.6.