Color-color diagrams using the photometry from Spitzer/IRAC. Left: [3.6]–[4.5] vs. [4.5]–[5.8] diagram for the IRAS 22147 region, where all 681 sources with distances and IRAC errors < 0.2 mag are shown. Normal stars are depicted as a Hess diagram (color bar), and excess PAH emission contaminants are shown with light green hexagons and Class I YSOs with red circles. The dark green diamond represents the source initially classified as a Class I YSO, but later re-classified as a heavily reddened Class II source, based on its 24 µm flux. Red × symbols indicate three objects identified as YSOs by Winston et al. (2019) but failing to pass our selection criteria (see Sect. 3.4). Right: [3.6]–[5.8] vs. [4.5]–[8.0] diagram for the IRAS 22147 region, with Class I YSOs and excess PAH emission contaminants from the left panel removed. Symbols are the same as in the left panel.