An IRDC filament along the Galactic plane, spanning across from the lower right (18.45°, –0.20°) to the upper left (19.30°, –0.02°). The top panel shows a 8 μm Spitzer image and the color stretch is chosen to bring the IRDC to prominence. The lower panel presents the intensity weighted peak velocity (moment 1) map of the GRS ¹³CO data. Regions with velocities outside the 43 km s^-1 to 51 km s^-1 are clipped. The green contours are from ATLASGAL with contour levels at 0.15 Jy or 3σ, 0.3 Jy, 0.4 Jy, 0.5 Jy, 0.7 Jy, 0.9 Jy, 1.3 Jy, 1.8 Jy, and 2.5 Jy. The yellow ellipses indicate the bubbles as given in Simpson et al. (2012).