Velocity-integrated intensity map of ¹²CO J = 3 → 2, convolved a 25′′ beam to match the resolution of the ¹²CO J = 11 → 10 map. The contour levels are the 10%, 25%, 50% (thick line), 75%, and 90% of the peak emission (770 K km s^-1). The central position (Δα = 0, Δδ = 0) labeled with a white cross, is the same as in Fig. 1. The ultracompact H II region M17-UC1 and four H₂O masers (Johnson et al. 1998) are labeled with the filled circle and plus symbols, respectively. The positions of the peak intensities of HCN J = 8 → 7 and ¹²CO J = 16 → 15, as well as the offset positions at (−60′′, −30′′) and (−130′′, +30′′) analyzed in Sect. 4.4, are indicated with a triangle, diamond, pentagon and star, respectively.