Magnitude–colour diagrams showing the magnitude in the various IRAC bands of the sources from the sample obtained in this work (black dots) as a function of [4.5] – [8.0]. Panels on the same row display, from top to bottom, the measurements for these sources in the 3.6, 4.5, 5.8, and 8.0 μm bands, respectively. In the left column panels, the sources from our sample are overlaid with those from GLIMPSE II (red dots). The green dots in the right column panels are those remaining from our photometry list after removal of sources contaminated by PAH emission. Only objects detected in all four bands with photometric errors <0.3 mag are plotted.