[5] Measurements made with the IRAS observatory give a diameter of 145.70±5.89 km and a geometric albedo of 0.03±0.01.

By comparison, the MIPS photometer on the Spitzer Space Telescope gives a diameter of 145.44±7.72 km and a geometric albedo of 0.03±0.01.

When the asteroid was observed occulting a star, the results showed a diameter of 148.00±16.26 km.

[6] A companion for 283 Emma was detected on 14 July 2003 by W. J. Merline et al. using the Keck II telescope and is designated S/2003 (283) 1.

The discovery was reported in the International Astronomical Union Circular (IAUC) 8165.