Colour maps of the integrated intensity of the J = 16 → 15, J = 12 → 11 and J = 11 → 10 transitions of ¹²CO, and the ¹³CO J = 13 → 12 line in M17 SW. The contour levels are the 10%, 25%, 50% (thick line), 75%, and 90% of the peak emissions. The central position (Δα = 0, Δδ = 0), labeled with a cross, corresponds to the star SAO 161357 at RA(J2000) = 18^h20^m27.6^s and Dec(J2000) = . The ultracompact H II region M17-UC1 and four H₂O masers (Johnson et al. 1998) are indicated with circle and plus symbols, respectively. The ¹³CO J = 13 → 12 map was convolved with a 25′′ beam to match the resolution of the ¹²CO J = 12 → 11 and to increase the S/N. All pixels with S/N< 3 (or an rms > 0.22 K) were blanked in the ¹³CO map.