Close-up of a few IRDCs in the 35.49-00.31 complex (see Fig. A.2 for the map of the entire complex). Left: near-infrared dust extinction map. The color scale is linear and spans A_V = 3 − 30 mag. The contour shows the detection threshold of the 8 μm opacity data (see the right panel). Center: integrated intensity of the ¹³CO molecule in the velocity interval 24.6–46.9 km s^-1. Right: 8 μm optical depth map. The white contour is drawn at τ(8   μm) = 0.3, or A_V ≈ 6.3 mag, representing the detection threshold of the data (Peretto & Fuller 2009). The color scale is linear with the maximum of A_V = 90 mag.