Comparison of CO and HNC emission in the field. Top left: velocity-integrated map of ¹³CO 1-0 from 40 to 52 km s⁻¹. The contour levels are 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, and 100σ, where σ is about 0.3 K km s⁻¹. Top middle: velocity-integrated map of ¹³CO 1-0 from 53 to 62 km s⁻¹. The contour levels are the same as in the top left. Top right: velocity-integrated map of ¹³CO 1-0 from 63 to 80 km s⁻¹ with the same contour levels. Bottom left: velocity-integrated map of HNC 1-0 from 40 to 52 km s⁻¹. The contour levels are 1, 3, 5, 7, and 9σ, where σ is about 0.25 K km s⁻¹. Bottom middle: velocity-integrated map of HNC 1-0 from 53 to 62 km s⁻¹. The contour levels are 3.0, 6.0, 9.0, 12.0, 15.0, 18.0, 21.0, 24.0, 27.0, and 30.0σ, where σ is 0.22 K km s⁻¹. Bottom right: velocity-integrated map of HNC 1-0 from 63 to 80 km s⁻¹. The contour levels are the same as in the bottom-left panel.