The secondary appears to be in synchronous rotation. See text for details.\
$^g$ These are the semiaxes of the uncertainty area; see its actual shape in Fig. \[66391\_LB\_polar\].\
$^h$ The $P_{\rm orb}$ and $L_0$ values are for epoch JD 2455305.0, for which $P_{\rm orb}$ and $\Delta M_d$ do not correlate.

In the first part of the table, we present data derived from optical and spectroscopic observations of the system. $H_V$ and $G$ are the mean absolute magnitude and the phase parameter of the $H$–$G$ phase relation (Bowell et al., 1989). Using $H_V$ and effective diameter of the whole system ($D_{\rm eff} \equiv (D_{1,{\rm C}}^2 + D_{2,{\rm C}}^2)^{1/2}$) at the mean observed aspect of 27 deg. (see below), we derived the visual geometric albedo $p_{\rm V}$. We note that our value is in agreement with the $0.19 \pm 0.05$ value derived by Devogèle et al. (2019) from their polarimetric observations. We also observed 1999 KW4 in near-infrared spectral range and classified it as a Q type asteroid (see Appendix A.).

In the next two parts of Table \[tablePropKW4\], we give parameters for the components of the binary. The indices 1 and 2 refer to the primary and the secondary, respectively.

$D_{i,{\rm 