Simulations of a sky region at high Galactic declination at the ALMA observing frequencies. 20 randomly distributed point sources with the same intensity have been added. Here, the point sources have a spectrum similar to that of CMB (see text and curve a₁ in Fig. 3). The PSFs are assumed to be Gaussian with a standard deviation of 3 pixels. Noise is Gaussian-white with standard deviation set to 0.12 time the standard deviation of the values in the corresponding noise-free maps. All of the point sources have the same intensity set to 1.7 times the standard deviation of the noise. The two bottom-right panels show the simulated point sources and their position on the 950  GHz map.