Closed-form Self-calibration of Large Radio Astronomical Phased Arrays

Calibration of large phased array telescopes like LOFAR and SKA-LOW is currently done using self-calibration techniques.These techniques are inherently iterative.In this contribution we present the Calibration of Large Arrays by Sub-Spaces (CLASS) method, which provides a closedform solution for self-calibration of direction-independent gains for large phased arrays.It uses differencing to filter the receiver noise powers and a subspace technique to calculate the receive path gains and (apparent) source powers.We investigate the weighting used for differencing, and compare its computational performance and validate its accuracy by comparison to the current state of the art method using actual LOFAR data.