Simple imaging scenario for a synthesis imaging array. Given azimuth and elevation angles direction cosines can be used to calculate a propagation vector ﹩{\boldsymbol{\rho }}﹩ for a signal of interest (SOI) and interferer(s). The array has been co-phased with inserted time delays to image a celestial SOI. Interferers corrupt the visibilities for the SOI and introduce artifacts in the resulting radio image.