Gain Estimation Methods for Polarized Radio Telescope Arrays

In radio telescope arrays, the complex receiver gains and sensor noise powers are initially unknown and have to be calibrated. This can be done by observing a strong astronomical point source. Here we extend the calibration algorithms to the case of dual polarized arrays. The algorithms are based on factor analysis and eigenvalue decompositions. We show that a single observation does not provide a unique solution. With two observations of two point sources with known brightness matrices, the gains can be estimated up to two unknown phases, and with three observations the ambiguity reduces to a single unknown phase.