Intrinsic half opening angle in the frequency range between 1 GHz–43 GHz. The angle varies between ∼1° and ∼6°. A decrease is observed within one parsec, while an approximately constant value of 2° −3° is determined downstream. We note that the discrepancy between the results at 1 GHz and 5 GHz, which may indicate that the jet cross-section is not fully detected at 5 GHz beyond 4 pc.