Blue lines are curves showing the theoretical dependencies of the HFS factors, f_21HFS (left) and f_32HFS (right), on the line width of the C³³S main component for sources in which only the main component was detected. The red dotted vertical and horizontal lines indicate the values of the minimal line widths where the factors are reaching almost 1.0, 19.0 km s⁻¹ for the J = 2−1 transition (f_21HFS ∼ 0.99) and 9.2 km s⁻¹ for the J = 3−2 transition (f_32HFS ∼ 0.99).