Parallaxes of the OB stars in the different parts of the CNC, shown as black diamonds. The errorbars in magenta and black show the 1σ and 3σ uncertainty of the parallax, respectively. The green horizontal line shows the parallax at 2.35 kpc, while the green dotted lines delimit the 2.1 kpc to 2.6 kpc range. The dashed vertical lines delimit the different sub-samples, i.e., the central Carina Nebula region (index 1–136), NGC 3324 (index 137–141), and NGC 3293 (index 142–240). The stars which are classified as foreground or background stars according to the “3σ”, the “2σ”, and the “1σ” criterion described in Sect. 2.3 are marked in red, orange, and yellow, respectively. Stars with a relative parallax uncertainty σ_ϖ/ϖ ≥ 0.3 are shown in light gray. The index numbers on the x-axis refer to the number of the stars in Table 1 (available at the CDS).