1311 Knopfia is a main belt asteroid with an estimated diameter of about 20 km. It was discovered on March 24, 1933 by K. Reinmuth at Heidelberg. The semi-major axis is 2.42 AU, the eccentricity is 0.045 and the inclination is a low 2.82 degrees.
This asteroid was observed on two consecutive nights in June 2009. The resulting lightcurve was quite noisy, but indicated a period of about 9.65 hours with an amplitude of about 1.3 magnitude. This is an asteroid that requires further observation.