Position-velocity diagrams for CO and [CI] emission in HD 163296. The diagram was made using the CASA task impv. The position axis is the apparent major axis of the gas disk. The starting position is (α_J2000, δ_J2000) = (17^h56^m21^s.548, −21°57′25″.902), while the end position is (α_J2000, δ_J2000) = (17^h56^m21^s.001, −21°57′19″.436). Only pixels with values higher than 3σ were used. The dashed horizontal line shows the system velocity, the curved dashed line shows the maximum radial velocity according to Eq. (1), and the straight solid black lines were obtained according to Eq. (2), enclosing where the emission is.