SMALL ANGULAR SCALE SIMULATIONS OF THE MICROWAVE SKY

We describe and compare two types of microwave sky simulations that ar e good for small angular scales. The first type uses expansions in sph erical harmonics, and the second one is based on plane waves and the f ast Fourier transform. The angular power spectrum is extracted from ma ps corresponding to both types of simulations, and the resulting spect ra are appropriately compared. In this way, the features and usefulnes s of Fourier simulations are pointed out. For l greater than or equal to 100, all the simulations lead to similar accuracies; however, the C PU cost of Fourier simulations is similar to 10 times smaller than tha t for spherical harmonic simulations. For l less than or equal to 100, the simulations based on spherical harmonics seem to be preferable.