in the mean anomaly with respect to a solution with constant orbital period. Examples of the long-period component data together with the synthetic lightcurves of the best-fit solutions are presented in Figs. \[66391\_00-19\_synth\] and \[2001sl9\_01-15\_synth\]. Uncertainty areas of the orbital poles are shown in Figs. \[66391\_LB\_polar\] and \[2001sl9\_01-15\_LB\_polar\].

We estimated realistic uncertainties of the fitted parameters using the procedure described in Scheirich and Pravec (2009). For each parameter, we obtained its admissible range that corresponds to a 3-$\sigma$ uncertainty.

![The RMS residuals vs. $\Delta M_d$ for solutions of the model of (66391) 1999 KW4 presented in Section \[NumModel\]. Each dot represents the best-fit result with $\Delta M_d$ fixed and other parameters varied. The plots were constructed using spherical shapes of both components; see text for details. []{data-label="RMS_vs_DMdKW4"}](66391_RMS_vs_DMd_png){width="\textwidth"}

![The RMS residuals vs. $\Delta M_d$ for solutions of the model of (88710) 2001 SL9 presented in Section \[NumModel\]. Each dot represents the best-fit result with $\Delta M_d$ fixed and other parameters varied. The plots were constructed using spherical shapes of both components; see text for details.[]{data-label="RMS_vs_DMdSL9"}](2001sl9_RMS_vs_DMd_png){width="\textwidth"}

Parameters of (66391) 1999 KW4 {#ParamsKW4}
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In this section, we summarize the best-fit model parameters of the binary system (66391) 1999 KW4 and overview previous 