[2] Marlu is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.

In the Moving Object Catalog (MOC) of the Sloan Digital Sky Survey, however, Marlu is a common carbonaceous C-type asteroid.

[12] In September 1981, a rotational lightcurve of Marlu was obtained from photometric observations by American astronomer Alan W. Harris.

[10] In 2016, a modeled lightcurve gave a concurring sidereal period of 7.78887±0.00005 hours using data from a large collaboration of individual observers.

[6][7][8] The Collaborative Asteroid Lightcurve Link adopts an albedo of 0.0431 and derives a diameter of 69.87 kilometers based on an absolute magnitude of 9.81.