Lightcurve and color of near-earth-asteroid 1989ML Original Research Article

The asteroid of 1989ML is an Amor type near-earth-asteroid, which is one of the most accessible asteroids by spacecraft, and consequently it has been selected as a backup target of the Japanese sample return mission, MUSES-C. In January 1996, the brightness of 1989ML had been brighter than 20-magnitude in R-band and we succeeded to observe it using a 1.05-m schmidt telescope with 1K CCD detector at Kiso Observatory, Japan. From the analysis of the data obtained for four nights, it is found that the rotational period of 1989ML may be 19 or 32 hours, and the amplitude of its brightness variation is about 1 magnitude in R-band. We have performed also VRI band colorimetry and found that the color of 1989ML is similar to that of C-type asteroid.