Results are presented on the determination of the initial extinction position and of ψ, for the application of the analytical method. The precision of the method must probably do not be affected by the determination of the initial position wih a smaller number of measurements. Deviations of ψ tend to increase as θ is increased. Based on Δ values, estimatives of ψ are qualitatively equivalent for θ = 15° and θ = 30°, but they are better than those for θ = 45°.