Top panel: Spitzer GLIMPSE (Benjamin et al. 2003) and MIPSGAL (Carey et al. 2009) three-color image of the region. Red: 24 μm, green: 8 μm, blue: 3.6 μm. Overlaid contours are the velocity-integrated ¹³CO(1-0) emission (− 5.0kms^-1 < v_lsr < 17.4kms^-1) from the Galactic Ring Survey (Jackson et al. 2006). Contours correspond to 3.5, 7.3, 11.2, 15 Kkms^-1. Middle panel: velocity-integrated ¹³CO(1–0) map of the region integrated within − 4.95kms^-1 < v_lsr < 17.36kms^-1. A scale bar of 500 pc is added assuming a kinematic distance of 9.8kpc. Bottom panel: Galactic-latitude-integrated ¹³CO(1–0) position-velocity map of the region (integrated from − 0.2° < b < 1°). The clouds G052.24+00.74, G051.69+00.74, the bubble at l ~ 50°, and the G52L nebula (Bania et al. 2012) are indicated in the middle and bottom panels. The velocity range we used to produce the ¹³CO(1–0) integrated intensity map is indicated in the bottom panel as the red shaded region. The emission at 5.2kms^-1 < v_lsr < 7.2kms^-1 is due to contamination from a different molecular cloud, and some of the emission lies on the red dashed line. This component has a smaller line width ≲0.5kms^-1, which implies that the contamination comes from a close-by cloud. This is supported by its apparent diffuse morphology. Channel maps of the region are provided in Appendix A.