Robust Calibration of Radio Interferometers in Multi-Frequency Scenario

TL;DR

This paper presents a robust, distributed calibration algorithm for radio interferometers that effectively handles outliers and frequency-dependent parameters, improving calibration accuracy for large-scale radio telescopes.

Contribution

It introduces a novel iterative robust calibration method based on relaxed maximum likelihood estimation tailored for multi-frequency radio interferometry with outliers.

Findings

Outperforms conventional calibration algorithms in simulations.

Effectively manages outliers and frequency-dependent variations.

Suitable for large, wide-field radio telescopes.

Abstract

This paper investigates calibration of sensor arrays in the radio astronomy context. Current and future radio telescopes require computationally efficient algorithms to overcome the new technical challenges as large collecting area, wide field of view and huge data volume. Specifically, we study the calibration of radio interferometry stations with significant direction dependent distortions. We propose an iterative robust calibration algorithm based on a relaxed maximum likelihood estimator for a specific context: i) observations are affected by the presence of outliers and ii) parameters of interest have a specific structure depending on frequency. Variation of parameters across frequency is addressed through a distributed procedure, which is consistent with the new radio synthesis arrays where the full observing bandwidth is divided into multiple frequency channels. Numerical simulations reveal that the proposed robust distributed calibration estimator outperforms the conventional non-robust algorithm and/or the mono-frequency case.