Radio continuum emission and H₂CO absorption seen by the Effelsberg 100 m telescope. (a) Effelsberg 4.89 GHz radio continuum emission overlaid with the peak absorption contours of H₂CO (1_1,0–1_1,1). The corresponding HPBW of H₂CO (1_1,0–1_1,1) is 3′. The color bar represents the flux densities of the radio continuum emission. The H₂CO absorption contours start from −0.5 K (5σ) and decrease by 0.5 K. The developed HII regions from Anderson et al. (2014) are marked with solid red circles, and SNR G78.2+2.1 is indicated by the dashed orange circle. Blue crosses represent the radio continuum sources and active star-forming objects, and the purple star represents the massive star cluster, Cygnus OB2. (b) Similar to Fig. 5a, but the corresponding HPBW of H₂CO (1_1,0–1_1,1) is 10′.8. The H₂CO absorption contours start from −0.08 K (4σ) and decrease by 0.06 K. In both panels, the beam size is shown in the lower left corner.