¹²CO/¹³CO ﹩J=3\rightarrow 2﹩ integrated intensity ratio for cuts at three different declinations through M17. The ratio was measured in a 15^{﹩\arcsec﹩} beam. The solid line connects measurements made at 0^{﹩\arcmin﹩} declination offset, the dashed line connects measurements made at −8^{﹩\arcmin﹩} declination offset, and the dotted line connects measurements made at 8^{﹩\arcmin﹩} declination offset. The error bars indicate a 15% calibration uncertainty. The (0, 0) position corresponds to ﹩\alpha ( 1950) =1﹩8^h17^m21﹩\fs﹩0, ﹩\delta ( 1950) =-1﹩6°06^{﹩\arcmin﹩}45^{﹩\arcsec﹩}.