[2] In the Tholen classification, Banachiewicza is a stony S-type asteroid,[1] while the overall spectral type of the Eos family is that of a K-type.

[12]: 23 In August 2008, the best-rated rotational lightcurve of Banachiewicza was obtained from photometric observations by French amateur astronomers Laurent Bernasconi, Cyril Cavadore and Stéphane Charbonnel.

Lightcurve analysis gave a rotation period of 8.631 hours with a brightness variation of 0.54 magnitude, indicative for an irregular, elongated shape (U=3).

[8] Other observations at the Palomar Transient Factory in California, and by a collaboration of Hungarian astronomers gave a period of 8.628 and 5 hours with an amplitude of 0.36 and 0.4 magnitude, respectively (U=2/2).

[13][10] In 2013, an international study modeled a lightcurve with a concurring period of 8.63043±0.00005 hours and found two spin axis of (214.0°, 62.0°) and (64.0°, 60.0°) in ecliptic coordinates (λ, β) (Q=2).