On the calibration and imaging with eigenbeams

We show that the majority of information is contained in the small number of linear combina- tions of the measured voltages. Therefore, a small number of synthetic beams, perhaps an order of magnitude smaller than the number of physical feeds, can be used for imaging and calibration. From the other side, only a small number of gains can be calibrated using the full-beam self-calibration approach. An algorithm to compute the beamformer weights for an optimal calibration has been described.