If γ γ ≫ ≫ 1 (i.e. when velocity of jet is close to the velocity of light) then β β T max > 1 despite the fact that β β < 1 . And of course β β T > 1 means that the apparent transverse velocity along C B , the only velocity on the sky that can be measured, is larger than the velocity of light in vacuum, i.e. the motion is apparently superluminal.