MSX, WISE, and Spitzer candidate YSOs projected onto the IRAC-GLIMPSE image at 8.0 and 5.8 μm. Cyan diamonds indicate the MSX sources, blue circles and blue squares indicate WISE Class I and Class II sources, respectively, and green circles and green squares indicate the Spitzer Class I and Class II sources, respectively. The numerical references of YSOs are based on those from Table A.1. The size of the symbols do not necessary match the angular size of the sources. Ionizing candidate stars identified in Sect 5.1 are also indicated by crosses in magenta (O9V), green (B1V), and yellow (B2V or later). White contours indicate the ¹³ CO emission of component A (first contour level ~8 rms) and theCO emission of feature 1 (first contour level ~13 rms), feature 2 (first contour level ~12 rms), and feature 3 (first contour level ~10 rms).