A Multisource Calibration Method for Phased Array Radio Telescopes

For low frequency observations (< 300 MHz) the radio astronomical community is currently developing a number of new instruments such as the low frequency array (LOFAR), the Mileura wide field array (MWA) and the primeval structure telescope (PaST). These telescopes require new calibration algorithms since phased arrays require an all-sky approach to imaging and calibration. This implies that the calibration will generally have to deal with a multitude of sources. In this paper we will discuss a multisource calibration method to estimate the gains and phases of the receiving elements without having to solve for the receiver noise powers at the same time. Our method is able to handle arbitrary known source models. We will show that the proposed algorithm is asymptotically efficient by comparing the results from Monte Carlo simulations with the Cramer-Rao bound for the underlying data model