Position velocity diagram of SO₂ (4_2,2 - 3_1,3) extracted along the disk orientation of IRS3C. The black contours show the 4, 8, and 16σ_line levels. The red line shows the profile for a Keplerian disk of 1 M_⊙ inclined by 50°, and for comparison, the dotted cyan and green lines show profiles for 0.5 M_⊙ and 2 M_⊙, respectively. A spectral and spatial resolution element (0.1 km s^-1 ×283 au) is indicated in the bottom left corner.