77733 2000 OS73 is a main belt asteroid with an estimated diameter of 10 km. It was discovered on July 21, 2001, by Spacewatch at Kitt Peak. The semi-major axis is 2.62 AU, the eccentricity is 0.091 and the inclination is 7.84 degrees.
This asteroid was observed on 2 nights during June, 2009, when it was in the field of another asteroid I was observing. A lightcurve with a period of 7.579 hours was derived from the data, however this result is very uncertain and more observations are required.