Example of the parameter error evaluation with PHOEBE, in the case of ASAS-073. Left panel: evolution of the cost function λ. Peaks represent iterations immediately after the kicks. A more significant (deeper, λ ≃ 1.25) minimum in the parameter hyperspace was found after iteration no. 350. Right panel: mapping the degeneration between Kopal’s modified potentials Ω. The solutions included in the final error calculation are plotted with black dots, and those that were rejected (shallower minimum or still before convergence) are plotted with grey circles. The red × symbol with error bars represents the best fit (lowest λ) and the final 1σ uncertainties.