(a) Combined ¹²CO (red) and ¹³CO (blue) integrated intensity map of Perseus (Ridge et al. 2006). The boundaries we define for each region (same as in Figure 1(b)) are shown in black. The centroid of each polygon is marked with a different colored point. (b) An R.A.–velocity diagram of Perseus, with the same color scale as panel (a). The colored points show the peak-reddening velocity (dark points) and average-reddening weighted velocity (light points) as a function of R.A. for each cloud. The error bars in R.A. show the horizontal extents of the polygons overlaid in panel (a). (c) Average reddening-weighted distance to each region as a function of R.A. (d) A velocity–decl. diagram of Perseus, with the same color scale as panel (a). The colored points show the decl. as a function of peak-reddening velocity (dark points) and average-reddening weighted velocity (light points). The error bars in decl. show the vertical extents of the polygons overlaid in panel (a). (e) The average reddening-weighted distance to each region as a function of its peak-reddening velocity (dark points) and average reddening-weighted velocity (light points). We find that the cloud distances tend to increase with both average reddening-weighted velocity and R.A. In total, the velocity gradient of ≈5 km s⁻¹ maps to a distance gradient of about 25 pc. The uncertainty provided on distance accounts only for the statistical uncertainty and does not include any systematic uncertainty, which we estimate to be 0.1 mag in distance modulus or 5% in distance (see Section 7).