Filtered maps of a region observed in 2010 at the 150, 220, and 280 GHz bands, from left to right, respectively. The gray scale is the same for the three maps going from −25 mJy to +25 mJy. The sources are the bright spots. Dusty sources are typically undetected or have low fluxes in 150 GHz maps, but their flux rises at higher frequencies. The opposite is true for synchrotron sources: they have higher flux at the lowest frequency. Note that the angular scale of the noise fluctuations is related to the beam size in these filtered maps.